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This paper aims to investigate the mechanical properties of specimens printed by 3D open-source printers. It discusses the effect of five factors (part orientation, layer height, extrusion width, nozzle diameter, and filament temperature) on the ultimate tensile strength and the impact toughness of the 3D-printed samples. A 25–1 resolution V fractional factorial experiment was run with the 16 samples printed on a Prusa I3 MK3S in PLA. Tensile strength and impact toughness were tested using Instron 3367 and Tinius Olsen 66 testers, respectively. In analyzing the data, a normal probability plot of the effects complimented with ANOVA (Analysis Of Variance) revealed that, for both responses, only part orientation was statistically significant at p = 0.05. Regression equations were used to predict the ultimate tensile strength and the impact toughness as a function of the part orientation. Both the toughness response and the tensile strength response are maximized with horizontal part orientation. Verification experiments have been implemented to validate the adopted regression equations' predictions under different circumstances, and the results of those experiments appear to confirm the model. [ABSTRACT FROM AUTHOR]

Welding metal alloys with dissimilar melting points makes conventional welding processes not feasible to be used. Friction welding, on the other hand, has proven to be a promising technology. However, obtaining the welded joint's mechanical properties with characteristics similar to the base materials remains a challenge. In the development of this work, several of the machine learning (ML) regressors (e.g., Gaussian process, decision tree, random forest, support vector machines, gradient boosting, and multi-layer perceptron) were evaluated for the prediction of the ultimate tensile strength (UTS) in joints of AISI 1045 steel and 2017-T4 aluminum alloy produced by rotary friction welding with laser assistance. A mixed design of experiments was employed to assess the effect of the rotation speed, friction pressure, and laser power over the UTS. Furthermore, the response surface methodology (RSM) was employed to determine an empirical equation for predicting the UTS, and contours maps determine the main interactions. A total of 48 specimens were employed to train the regressors; the 5-fold cross-validation methodology was used to find the algorithm with greater precision. The gradient boosting regressor (GBR), support vector regressor (SVR), and Gaussian processes regressors present the highest precision with a less than 3% percentage error for the laser-assisted rotary friction welding process. The GBR and SVR capability exceed the RSM's accuracy with a coefficient of determination (R2) greater than 90.9 versus 83.2%, respectively. [ABSTRACT FROM AUTHOR]

The main goal of this study is the modeling of ultimate tensile strength produced by friction stir welding of AA2024-T3 aluminum alloy using Taguchi and surface response methodologies. The considered process parameters are tool rotation speed, tool traverse speed, and wiper™ tool geometry (shoulder diameter). Analysis of variance, signal to noise ratio, and main effects plot used to check which process parameters were statistically significant and have better quality characteristics. Linear regression model was used to predict the ultimate tensile strength of the welded joints by incorporating process parameters. By using sensitivity analysis, the effectiveness of process parameters and the most significant parameter have been shown. From this research, the optimal experimental condition which gives the maximum ultimate tensile strength was obtained with a tool rotation speed of 750 rpm, a tool traverse speed of 100 mm/min, and a tool shoulder diameter of 12 mm which is 84% of joint efficiency of the base metal. The ultimate tensile strength increased to a maximum value and could be decreased with increasing tool rotation speed. Moreover, increasing the tool traverse speed or the tool shoulder diameter also make it decreased. Microscopic analysis showed that the increasing of the tool rotation speed or tool shoulder diameter results in an increase of average grain size in the nugget zone while it decreased slightly as tool traverse speed increases. [ABSTRACT FROM AUTHOR]

Nickel alloys have gathered wide acceptance in the fabrication of components, which require high temperature resistance and corrosion resistance, such as metal bellows used in expansion joints in aircraft, aerospace, and petroleum industry. In case of single pass welding of thinner sections of this alloy, pulsed current micro plasma arc welding (PCMPAW) was found beneficial due to its advantages over the conventional continuous current process. The quality of welded joint depends on the grain size, hardness, and ultimate tensile strength, which have to be properly controlled and optimized to ensure better economy and desirable mechanical characteristics of the weld. This paper highlights the development of empirical mathematical equations using multiple regression analysis, correlating various process parameters to grain size, hardness, and ultimate tensile strength in PCMPAW of Inconel 625 sheets. The experiments were conducted based on a five-factor, five-level central composite rotatable design matrix. A genetic algorithm (GA) was developed to optimize the process parameters for achieving the desired grain size, hardness, and ultimate tensile strength. [ABSTRACT FROM AUTHOR]

Friction stir welding (FSW) is a highly reliable joining process. However, there is still lack of optimized FSW parameters for different joint configurations. The present manuscript presents a set of optimization studies for different friction stir welding joint geometries of AA6082-T6 aluminium alloy: butt, lap and T joints. The optimization process was performed using Taguchi orthogonal arrays (OA) for designing experiments, analyses of the average effects (main effect plot) and variance (ANOVA). Welded joints were manufactured according to orthogonal arrays, selected using the Taguchi method, for each type of joint, and the ultimate tensile strength (UTS) was evaluated for statistical optimization. As a major asset for the current state of the art, this manuscript contribution is focused on the determination of the most relevant FSW parameters on UTS for a complete range of joints, as well as their interactions. In the particular case of lap and T joints, parameter optimization studies are lacking in the literature, and as such, this work aims at tackling the issue. The parameter combinations to achieve the best mechanical properties for each joint configuration were derived. [ABSTRACT FROM AUTHOR]

A series of welds were made by friction stir welding (FSW) under different welding and rotation speeds. A 2D ultimate tensile strength (UTS) map was developed based on various experimental data to predict the UTS of friction stir welded AA2024 alloy joints. The accuracy of the UTS map was evaluated by comparing the estimated UTS with the corresponding experimental results from the FSW of the same material available in the open literature. Analytical models were developed to estimate the peak temperature and grain size in the nugget zone. The predicted optimal peak temperature and welding and rotation speeds for AA2024 were within the windows of 400-465 °C, 175-350 mm/min and 800-1,200 rpm, respectively, under which the joint tensile strength could be higher than 458 MPa (about 94.6 % of the base metal) and the estimated average grain sizes in the nugget zone were about 2-3.9 μm. [ABSTRACT FROM AUTHOR]

This study proposed the direct extrusion and continuous-shear deformation (DECS) process for the co-extrusion of Mg-AZ31B/Al 6063, aiming to prepare high-plasticity Mg/Al composite sheets. The effect of extrusion temperature on the microstructure and mechanical properties of the Mg/Al composite sheet was systematically studied. The results show that Mg/Al composite sheets with no voids or cracks at the interface were successfully prepared by the DECS process. The microstructure of the Mg layer at different extrusion temperatures primarily consists of equiaxed fine grains, with grain sizes of 7.29 μm, 8.98 μm, and 9.88 μm at 330℃, 360℃, and 390℃, respectively. The Mg layer exhibits a typical extrusion texture, with the c-axis of most grains parallel to the transverse direction (TD). With the increase in extrusion temperature, the c-axis of some grains deviates from the TD toward the normal direction (ND). The Al layer mainly consists of elongated deformed grains and fine dynamically recrystallized (DRXed) grains distributed along the extrusion direction (ED). The AZ31 Mg alloy with refined grains maintains the ultimate tensile strength of the Mg/Al composite sheet, while the Al matrix enhances its plasticity. At 330℃, the Mg/Al composite sheet shows an ultimate tensile strength of 244.48 MPa ± 4.35 and an elongation of 39.42% ± 0.06. The influence of the bonding layer thickness on the shear and tensile properties of the composite sheet was studied, revealing that increasing the bonding layer thickness reduces the shear strength of the Mg/Al composite sheet but positively affects its tensile strength. [ABSTRACT FROM AUTHOR]

Additive friction stir deposition (AFSD) is attractive for its ability to create freeform and fully dense structures without melting and solidification. Hence, additive friction stir deposition is an alternative to fusion-based additive manufacturing technology. In this study, the influence of the AFSD parameter (i.e., rotational speed and feed rate) on the mechanical properties and microstructure of 6061 aluminum alloy is investigated. The as-deposited 6061 aluminum alloy exhibits a relatively homogeneous microstructure with extensive equiaxed grains. Compared to the feedstock material, the ultimate tensile strength of the as-deposited 6061 aluminum alloy decreased to 65% from 320 to 210 MPa. The results of electron backscatter diffraction indicate that continuous dynamic recrystallization occurs during the AFSD process. Furthermore, it is evidence that the grain size and ultimate tensile strength are positively correlated with feed rate and rotational speed, whereas the elongation at break decreases with the increase in feed rate and rotational speed. [ABSTRACT FROM AUTHOR]

The present study aims to investigate the effect of the mechanical and metallurgical joint strength behavior of Cr-Ni-Mo steel (AISI 316) using direct drive friction welding. Experimental procedures in the study included macrostructure, microhardness, tensile test specimens with effective diameters of 4 mm, 6 mm, and 8 mm, microstructure of the fracture position, and tensile fracture morphology. The results concluded that the average microhardness values for 4 mm, 6 mm, and 8 mm diameter around the weld interface center are 298 Hv0.1, 300 Hv0.1, and 295 Hv0.1, respectively. The ultimate tensile strength ratios were of 95%, 98%, and 97% for 4 mm, 6 mm, and 8 mm, respectively, while, the ductility increased with the diameters of 41%, 50%, and 57% for 4 mm, 6 mm, and 8 mm, respectively, compared to AISI 316. The fracture position for all welded joints was in the adjacent region to the interface. The fracture surfaces had a fingerprint form and ductile mode at cleavage features. The center of the fracture revealed different forms of dimples and microcavities collected at that center. [ABSTRACT FROM AUTHOR]

Currently, in pipe welding, it is nearly difficult for a human welder to weld the whole circumference of a pipe in a single uninterrupted pass using MIG welding causing inconsistencies in weld quality around the welded pipe. The aim of this study was to develop an automated orbital pipe MIG welding system and to optimize welding parameters for enhancing ultimate tensile strength and Rockwell hardness of mild steel 1020 grade pipe. Three levels of variation were applied to the four input parameters that were chosen. Nine experiments were carried out using orthogonal array of L9. In this experimental investigation, the highest ultimate tensile strength (UTS) of 411.2 MPa and Rockwell hardness (RH) of 95 HRB were achieved at 110 A of current, 24 V of voltage, welding gun travel speed of 30 cm/min, and 3 mm of arc length. For modeling the orbital pipe MIG welding process experimental input parameters and response results, a hybrid artificial neural network and genetic algorithm (ANN-GA) model was constructed. This model was used to forecast and optimize UTS and RH, as well as the process factors that go with it. The results indicated that the ANN-GA model could predict the output responses with a mean square error of 5.06e-05. During optimization, a 4–9-2 network trained with neural network of back propagation by Bayesian regularization approach was determined to have the greatest prediction capability, with maximum UTS and RH of 417.857 MPa and 96.5364 HRB, respectively. From the confirmation tests, the average results of 412.7 MPa of UTS and 95 HRB of HR were obtained. The percentage of errors between the ANN-GA predicted optimal responses' results and the confirmatory experimental results were found 1.23% and 1.59% for UTS and RH, respectively. [ABSTRACT FROM AUTHOR]

Ablation sand casting is a new technology for casting aluminum alloys which helps to achieve superior cooling trends during the solidification and results in eutectic microstructure, reduced degree of defects, and improved mechanical attributes. To further enhance the functionality, water-soluble binder-based sand molds are used in conjunction with appropriate control over process parameters for specialized applications such as complex and thin-walled impeller manufacturing. In this regard, the influence of key process parameters including binder ratio (BR), sand grain fineness number (AFS number), and pouring temperature (PT) is investigated thoroughly on the mechanical characteristics (ultimate tensile strength and hardness) and dimensional accuracy of the thin-walled impeller. Ablation sand casting revealed exceptionally enhanced mechanical properties and dimensional accuracy as compared to conventional sand casting. The AFS number and binder ratio were most significant for controlling the dimensional accuracy. Multi-response optimization through Grey Relational Analysis reveals the optimal setting PT = 800 ℃, ASF number = 45, BR = 5% for lower dimensional deviation, higher hardness, and ultimate tensile strength through conventional sand casting. While for ablation case, the optimal conditions PT = 850 ℃, ASF number = 40, BR = 9% are attained against desired attributes. The attributes are significantly improved through ablated sand casting, dimensional accuracy 31.6%, hardness 58.9% and ultimate tensile strength 41.82%, and fractography analysis depicted the ductile fracture surface. The current technology is drawing attention of industry because of its potential in producing castings with superior mechanical properties and improved internal integrity. [ABSTRACT FROM AUTHOR]

In the present work, the effect of build-up orientation angle and printing speed on mechanical properties of 17-4 PH stainless steel components realized by Bound Metal Deposition technology was investigated. Furthermore, the presence of microscopical and macroscopical defects was analyzed as a function of the printing parameters investigated. To this purpose, tensile specimens, printed with different build-up orientation angles (0°, 45°, and 90°) and printing speeds (15, 30, 45, and 60 mm/s), were tested at room temperature to evaluate the mechanical properties as a function of the process parameters. Furthermore, stereo optical microscopy and scanning electron microscopy coupled to energy dispersive X-ray spectroscopy were used, respectively, to observe the macroscopical and microscopical defect presence on the 3D printed parts built with different build-up orientation angles and printing speeds. It was demonstrated that the build-up orientation angle and printing speed significantly affect the mechanical properties and the surface finish of 3D printed components, as well as the presence of micro-defects due to the layer-by-layer filament deposition. In particular, the build-up orientation angle of 45° confers less mechanical to the specimens than the other two orientations investigated, both in terms of ultimate tensile strength, yield strength, and modulus of elasticity. Furthermore, high print speeds do not significantly contribute to a worsening of mechanical performance but influence the surface finish which is characterized by greater printing defects. [ABSTRACT FROM AUTHOR]

This article presents the results of pilot studies on the lubrication of the blankholder zone in sheet metal forming using a pressurised lubricant. The authors invented a method and built a special tribometer for pressure-assisted lubrication. This approach reduces friction in sheet metal forming processes compared to conventional lubrication. Moreover, the artificial neural network approach combined with a force-directed Fruchterman-Reingold graph algorithm and Spearman's correlation was used for the first time to analyse the relationships between the friction process parameters and the output parameters (the coefficient of friction and the resulting surface roughness of the sheet metal). The experimental tests were conducted utilising strip drawing on four grades of steel sheets known to be outstanding for deep-drawing quality. Different oils, oil pressures and contact pressures were used. Artificial neural network models were used for the first time to determine these relationships in a strip drawing test where every parameter is represented by one node, and all nodes are connected by edges with each other. R Software version 4.2.3 was used to construct the network using the 'qgraph' and 'networktools' packages. It was found that friction conditions had a highly significant negative correlation with coefficient of friction (COF) and a moderately significant negative correlation with the final surface roughness. However, the initial surface roughness of the as-received sheets had a negative correlation with the COF and a positive one with the resulting surface roughness of the sheet metal. The parameters most related to the COF are the strength coefficient, the ultimate tensile strength and the friction conditions (dry friction or pressurised lubrication). Spearman's correlation coefficients showed a strong correlation between the kinematic viscosity and the friction conditions. [ABSTRACT FROM AUTHOR]

The work is devoted to the study of bimetallic structures "titanium-steel" by electron beam freeform fabrication with the use of niobium and copper interlayers. A metallographic study of the deposited interlayers is carried out. The hardness distribution over the samples is shown. Technological issues according to deposition of niobium on titanium and steel on copper are pointed out. Tensile testing results reveal that the obtained structures have an ultimate tensile strength of 150–228 MPa and the fracture is located at the niobium-copper alloy side or at the niobium interlayer. The need to reduce the titanium content in niobium due to the occurrence of intergranular penetration of copper is demonstrated. [ABSTRACT FROM AUTHOR]

This paper investigates the cold spray additive manufacturing of a thick wall made of pure Al powder with a granulometry of + 45–15 μm with a size d50 = 26.95 µm. A high wall with vertical lateral faces is obtained without clogging, using a compensation building strategy and gas pressurization at 30 bars, 400°C. Layer by layer, using a suitable set of deposition parameters, the profile of the deposit grows without a lack of material at the lateral edges and then produces the near-net shape 3D wall. However, a structural characterization shows an issue of pore development and low mechanical properties. A porosity with a typical pore size range of 6–100 µm is observed from the bottom zone to the top zone of the wall, with a random occurrence and with a fraction of pores up to 8%. The distribution of the pore size shows a high fraction of fine pores (6–10 µm) up to ~ 70%. There can be a weak fraction (~ 0.04%) of larger pores (130–200 µm) and such pores appear as a continuous connexion of pores within the deposit due to a bad stacking and a bad bonding of particles during the additive growth. These detrimental defects ease the brittle mechanical behaviour of the wall during a tensile test. An intergranular-like fracture is observed with some trace of dimples but the brittle stress/strain curve until rupture suggests a predominant failure by cleavage due to the porosity. The fracture strain is less than 2%. The ultimate tensile strength and the elastic modulus are limited to about 50 MPa and about 50 GPa, respectively. [ABSTRACT FROM AUTHOR]

The demand for 3D-printed high-performance polymers (HPPs) is on the rise across sectors such as the defense, aerospace, and automotive industries. Polyethyleneimine (PEI) exhibits exceptional mechanical performance, thermal stability, and wear resistance. Herein, six generic and device-independent control parameters, that is, the infill percentage, deposition angle, layer height, travel speed, nozzle temperature, and bed temperature, were quantitatively evaluated for their impact on multiple response metrics related to energy consumption and mechanical strength. The balance between energy consumption and mechanical strength was investigated for the first time, contributing to the sustainability of the PEI material in 3D printing. This is critical considering that HPPs require high temperatures to be built using the 3D printing method. PEI filaments were fabricated and utilized in material extrusion 3D printing of 125 specimens for 25 different experimental runs (five replicates per run). The divergent impacts of the control parameters on the response metrics throughout the experimental course have been reported. The real weight of the samples varies from 1.06 to 1.82 g (71%), the real printing time from 214 to 2841 s (~ 1300%), the ultimate tensile strength from 15.17 up to 80.73 MPa (530%), and the consumed energy from 0.094 to 1.44 MJ (1500%). The regression and reduced quadratic equations were validated through confirmation runs (10 additional specimens). These outcomes have excessive engineering and industrial merit in determining the optimum control parameters, ensuring the sustainability of the process, and the desired functionality of the products. [ABSTRACT FROM AUTHOR]

The rheological, mechanical, and electrical properties and structure of rods and wires made of aluminum alloy concentration of 1% REM (0.6% Ce and 0.4% La) are investigated and presented. The rods were produced by combined rolling-extrusion (CRE) from two different types of billets: casting into a mold 14×14 mm and into electromagnetic mold (EMM) Ø12.5 mm. A database of the DEFORM 3D complex was created for computer modeling of the CRE process. The tensile strength of rods Ø9 and 5 mm obtained using CRE method is 120–140 MPa and elongation to failure is 15–26% for billets from EMM. For billets 14×14 mm, the ultimate tensile strength is 112–125 MPa, which is comparatively lower than that of rods made from round billets (elongation to failure is 26–34%). The plastic properties of the final wire Ø2 mm from a round billet after EMM are higher than wire Ø2 mm from a billet obtained by casting into a mold 14×14 mm. Rods after CRE from both types of billets are characterized by fairly high ductility. To obtain Ø2-mm wire from rods, no intermediate annealing was required. The values of electrical resistance are taken from 0.02271 to 0.0301 Ω‧mm2/m for rods from 12.5-mm billets and from 0.02776 to 0.03413 Ω‧mm2/m for rods from billets 14×14 mm. The electrical resistance values for wire Ø2 mm from billets 14×14 mm are higher than for wire obtained from rods after EMM. Microstructure shows that the final wire after CRE from billet in EMM has a more extensive structure than after CRE from billets with dimensions of 14×14 mm. [ABSTRACT FROM AUTHOR]

In this work, dissimilar welded joints from AISI 1330 and AISI 4340 low-alloy carbon steels produced using rotary friction welding (RFW) are investigated. These steels are intended for the manufacture of exploration drill pipes: AISI 4340 — the tool joint and AISI 1330 — the body of the pipe. Statistical analysis based on response surface methodology (RSM), microstructural examination using scanning electron microscopy with backscattered electron diffraction (EBSD), and mechanical tests were performed to investigate the friction weld joints. Equations are derived for predicting the notch tensile strength, ultimate tensile strength, and relative elongation from RFW process parameters (heating pressure, forging pressure, rotation speed during heating, burn-off length). The results showed that the rotation speed during heating and the heating pressure to the greatest extent affect the quality of the welded joint. Parameters have been established that ensure obtaining the mechanical properties of the welded joint at the level of the base metal AISI 1330: heating pressure 60–80 MPa, forging pressure 120–140 MPa, rotation speed during heating 400 rpm, and burn-off length 4 mm. It is shown that the strength of the joint depends on the development of processes of mutual dynamic recrystallization at the steel interface and strain hardening in the thermomechanical affected zone. [ABSTRACT FROM AUTHOR]

This article presents a reliable method of multi-performance characteristics optimization of TIG dissimilar welding of mild steel and stainless steel. Grey-integrated Taguchi optimization approach was adopted for the optimization of the welding process parameters such as the welding current, the welding voltage and the gas flow rate for multi-performance characteristics such as the ultimate tensile strength, yield strength, percentage elongation and Vickers microhardness of the fusion zone. L9 Taguchi orthogonal array was employed with three process parameters all at three levels. The welding current was the most significant process parameter for the multi-performance characteristics of the weld joint. The optimal setting for the multi-performance characteristics of the weld joint was obtained as welding current at level 1 (110 A), welding voltage at level 1 (11 V) and gas flow rate at level 3 (18 l min−1). The corresponding response variables at the optimal setting were ultimate tensile strength, yield strength, percentage elongation and Vickers microhardness of 493.29 MPa, 395.38 MPa, 31.35% and 390.52 HV respectively. These values are all found to be higher than the values obtained at the initial settings. This shows that grey-integrated Taguchi optimization is an effective method in multi-performance characteristics optimization of dissimilar welded material. [ABSTRACT FROM AUTHOR]

Producing bulk high-specific strength materials that replace steel airframe structures like stringers is the only optimistic alternative that can meet the future needs of the aviation sector. Stir casting, a prominent fabrication route to produce bulk materials, is employed in the current investigation to prepare aluminum composites reinforced with graphene nanoplatelets. However, the influence of dross on reinforcement infiltration into melt is unexplored by researchers and hence essential. The critical experimental insights reveal that dross hinders the nanoreinforcement incorporation into the melt; i.e., 25 to 40% of introduced GNPs are entrapped in dross. Moreover, superior mechanical behavior with an ultimate tensile strength (UTS) of 203 MPa led by a good uniform distribution of GNPs with no evidence of voids and clusters is observed for 1.5 wt.% GNP cast sample. Quantitative X-ray maps and EDS analysis reveal no iron contamination and their intermetallic compounds that degrade the strength of cast samples. [ABSTRACT FROM AUTHOR]

2219 aluminum alloy thin-walled tubes were fabricated by multi-pass spinning process, and then heat treatments were employed to optimize the mechanical properties of the spun tubes. It is shown that severe deformation during the spinning leads to the formation of large number of nanoscale subgrains, which causes the decrease of work hardening rate, ultimate tensile strength, and fracture strain. The solid solution at 530℃/30 min results in the full recrystallization and leads to the disappearance of the nanoscale subgrains. Besides, the micron scale precipitates in the as-spun tubes are refined to be nanoscale via the further aging process conducted at 175℃/18 h. It is why the ultimate strength of the tubes is enhanced from 245 to 435 MPa. By using of the spun tubes, 2219 aluminum alloy bellows with four circumferential waves were successfully formed by multi-step single wave hydroforming process. [ABSTRACT FROM AUTHOR]

This study investigates the influence of surface finish and post-processing conditions on the mechanical properties of 17-4 PH stainless steel (SS) produced using the atomic diffusion additive manufacturing process (ADAM). Diverse sample orientations, including horizontal (0°), 30°, 60°, and vertical (90°), were examined, with selected samples undergoing post-processing through machining, polishing, and heat treatment. Tensile strength testing, surface roughness measurement, and hardness measurement were conducted to assess the effect of surface finish conditions and post-processing on mechanical properties. The results reveal significant variations in the tensile strength of the samples based on the build orientation (183.5 to 1034.5 MPa), and subsequent machining. Notably, post-built machining is found to enhance both the absolute ultimate tensile strength (UTS) and the isotropy of the material. Further improvements are attainable through heat treatment. A microstructure analysis, in conjunction with tensile testing outcomes, demonstrates the potential for refining the properties of ADAM-printed samples through suitable machining, heat treatment, and geometry modifications. This study identifies avenues for ongoing process development and outlines possibilities for enhancing mechanical properties of additive manufactured parts, particularly through ADAM process. [ABSTRACT FROM AUTHOR]

The joining of titanium and stainless steel is challenging with conventional filler metals due to the formation of Fe-Ti intermetallic compounds (IMCs). Therefore, a filler that is compatible with both metals is necessary to avoid these IMCs and enhance the mechanical properties of Ti-SS joint. This research aims to investigate the effect of novel Nb-Cu composite filler on mechanical and microstructure properties of TA7-SS304 dissimilar hybrid composite joints using gas tungsten arc welding (GTAW) process. The mechanical properties: ultimate tensile strength (UTS) and micro hardness have been analyzed and assessed through the microstructure of weld interfaces and fracture zones. Results revealed that welding current (I) affects the UTS significantly whereas micro hardness is greatly influenced by welding speed (Ws). The maximum UTS of 293 MPa and micro hardness of 100 HV as well as minimum tensile residual stresses of 180 MPa and 170 MPa on SS 304 and TA7 sides, respectively have been attained at optimal parameters of I = 40 A, Ws = 150 mm/min and GFR = 18 lit/min. SEM and EDS analysis showed that presence of Cu and Nb solid solutions in the fusion zone contributed to improvement in UTS. Ductile fracture surface with no prominent defects is obtained at optimal combination, while brittle fracture with voids and cavities is observed for low-strength joints. X-ray diffraction analysis depicted that the formation of TiFe, Ti2Fe, and TiFe2 compounds and direct mixing of base metals have been successfully inhibited by using Nb-Cu composite filler which improved the Ti-SS bonding. [ABSTRACT FROM AUTHOR]

For a past few years, laser powder bed fusion (LPBF) process faced many issues such as cavity creation, unstable thermal capillary convection, and thermodynamic instability during the printing of Cu-Cr-Zr alloy. Hence, the important LPBF process variables such as exposure duration (ED) of 300, 400, and 500 µs; laser power (LP) of 370, 420, and 470 W; and overlapping percentage (OP) of 20, 40, and 60% needs to be examined based on the interactions of various combinations of parameters to fabricate a Cu-Cr-Zr alloy parts with reduced porosity, maximum ultimate tensile strength (UTS), and minimum nano-indentation depth (NID). Moreover, analytical studies were also performed based on the COmplex PRoportional ASsessment (COPRAS) approach. The proposed analytical approach shows better concurrence with the experimental observations. The optimal and initial variables obtained from the analytical and experimental approach were compared. The Cu-Cr-Zr alloy printed with optimal parameter settings possesses maximum UTS of 367 MPa and minimum NID of 321.51 nm. These enhanced results were mainly due to the occurrence of reduced porosity of 0.27%. Moreover, FESEM based fracture mechanism were investigated to study the propagation of cracks based on the defects formation. [ABSTRACT FROM AUTHOR]

The double-pass butt welding process was carried out on 9-mm-thick 2014-T4 aluminum alloy T-joints by stationary tool shoulder friction stir welding (STS-FSW). Microstructure changes were analyzed by grain and EBSD, combined with the evolution of the precipitation phase, to explore the influence of regulations of different process parameters on T-joints' mechanical properties. Defect-free T-butt joints were obtained within the rotational speed range of 400–500 rpm and the welding speed range of 100–140 mm/min. Due to severe dynamic recrystallization, the weld nugget zone exhibits fine equiaxed grain characteristics, with a grain size of approximately 10 μm. The degree of recrystallization and deformation in the weld nugget overlapped zone (WNOZ) did not significantly change, and the grain size of WNOZ was approximately 4 μm. T-joints' hardness has an uneven distribution, and the hardness is greatest in the weld nugget zone at 110–125 HV. The T-butt joints have the weakest hardness at the skin and stringer in the TMAZ, approximately 70–80 HV. The ultimate tensile strength of the skin and stringer in the T-butt joints is equivalent to 85% and 59.6% of the base material. According to the fitting of a quadratic polynomial with multiple variables, it is found that the maximum tensile strength of the skin and stringer can only be achieved when the thermal input is within a reasonable range. The fracture is a ductile fracture with numerous dimples visible on the fracture surface. The tensile fracture of the specimen is analyzed by the finite element method. T-butt joints exhibit lower stress concentrations during the tensile test than T-fillet joints. [ABSTRACT FROM AUTHOR]

Friction stir welding of aluminum alloys is today an essential joining technic for various industrial sectors. However, making a quality joint is relatively expensive compared to the electric arc welding processes. The aim of this work is to maximize the ultimate tensile strength (UTS) of AA3004-H32 aluminum alloy butt joint and minimize its production cost. The welding parameters are rotational speed, welding speed, and pin shape of the tool. Then, a test campaign is carried out according to the Box-Behnken design of experiments. Mathematical models of power consumption and ultimate tensile strength were developed by multiple linear regression. The analysis of variance (ANOVA) of the experimental data revealed the preponderant effect of the tool rotational speed and the pin profile on the studied responses. The bi-objective optimization problem was solved using the genetic algorithm and optimal welding parameters were presented. In terms of joint quality and electrical energy consumption, the results showed that the tool rotational speed plays a key role, and that the threaded cylindrical profile of the pin is the most preferred compared to other studied shapes. The welding speed is the most significant parameter in reducing welding costs. The approach proposed in this study can be used as a guide and recommendation to reduce FSW costs and at the same time ensure the quality of the AA3004-H32 alloy joint. [ABSTRACT FROM AUTHOR]

Metal additive manufacturing (AM) has become a widely adopted technique in various industries, owing to its flexible free-form manufacturing capabilities. M300 steel is widely applicable in industrial applications due to its exceptional mechanical properties, including superior strength and toughness. This study explores the effects of three selective laser melting (SLM) parameters—laser power, laser speed, and hatching distance—on M300 steel's hardness, surface roughness, elongation, and ultimate tensile strength (UTS). Microhardness findings reveal higher values at the sample edges compared to the center. Surface roughness analysis shows irregular patterns of roughness at different direction with the minimum roughness along the building direction. The combination of maximum UTS of 1078 MPa and elongation of 0.12% is obtained in this study. Statistical analysis identified laser power the most significant parameter on the roughness value with 52.2% contribution. In contrast, laser power minimally affects UTS (0.69%), while hatch distance dominates with a 59.10% contribution. Response surface methodology (RSM) highlights that reducing hatch distance and laser power increases UTS and decreases roughness. However, decreasing laser speed raises UTS but significantly increases surface roughness. Finally, a regression model enables UTS prediction for samples. This study enhanced the understanding of how SLM parameters affects M300 steel mechanical characteristics, facilitating decisions in SLM processes. [ABSTRACT FROM AUTHOR]

Transient liquid phase (TLP) bonding can be used to join Inconel 718 superalloy because the bond properties are similar to the parent material properties. The microstructure of TLP bonded sample showed presence of centerline eutectics in the isothermally solidified zone and boride precipitates in the diffusion-affected zone. These precipitates reduce the mechanical properties of the joints. The eutectics and borides should be minimized to enhance the mechanical properties of the bond. Post bond heat treatment (PBHT) processes can be implemented to improve the mechanical properties without inducing any harmful effect of prolonged heating. In the present work, the effect of PBHT technique (i.e., solution treatment and double aging) on the microstructural evolution and improvement in mechanical properties were investigated. The ultimate tensile strength (UTS) and microhardness of the TLP bond before and after the PBHT were analyzed and compared with the as-received workpiece. FESEM, FETEM and XRD analysis were used to quantify different precipitates formed during PBHT of TLP bond. The results showed that the PBHT improved the microstructure and mechanical properties of the bonded samples. After the solution treatment and double aging, a maximum UTS of 1210 MPa was obtained, which correspond to a 113.5% increase. The improvement of bond strength was attributed to increase volume fraction of γ′ and γ″ type strengthening phases during double aging and a decrease in the fraction of Nb-Mo type borides in the diffusion-affected zone. PBHT improved hardness of ISZ, DAZ, and BMZ by 33, 46, and 85%, respectively. [ABSTRACT FROM AUTHOR]

Many practical casting process optimization problems are ascribable to multi-attribute optimization problems with multiple conflicting quality attributes. This paper proposes a reasonable multi-attribute optimization and influence assessment methodology of casting process parameters combined with integrated multi-attribute decision-making (MADM) and Taguchi method. The proposed methodology consists of the following steps: (1) design experiment arrangement based on Taguchi orthogonal array, and measure multiple quality attributes of castings at every experimental trials, (2) calculate comprehensive quality score (CQS) values of the experimental trials using some MADMs, (3) calculate final CQS (FCQS) values of the experimental trials by integrating the CQS values from some MADMs using integrated MADM, (4) calculate mean FCQS values of the casting process parameters at different levels, (5) calculate ranges of mean FCQS values and influence indices of the casting process parameters, and (6) determine optimal casting process parameters to maximize the comprehensive quality of the castings. To demonstrate its usage and effectiveness, it is applied to one illustration example to determine optimal four casting process parameters such as pouring temperature (PT), degasser amount (DA), holding time (HT) and mould type (MT) for optimizing three quality attributes such as density of casting (D), ultimate tensile strength (UTS) and elongation to fracture (Ef) of A356 Al alloy sand castings. The proposed methodology could be widely applied to not only casting process optimization but also various advanced manufacturing process optimization problems. [ABSTRACT FROM AUTHOR]

The speed function (SF) parameter, which is a unique combination of beam speed and beam current, is one of the most important parameters of the electron beam melting (PBF-EB) production process. It allows the same process conditions (size of the melt pool, process temperature, etc.) to be maintained for parts with different geometries and sizes. The aim of this research was to understand the effect of SF on the Ti-5Al-5Mo-5V-1Cr-1Fe alloy produced by electron beam melting technology. The results showed that increasing the SF from 86 to 116 resulted in a decrease in the average process temperature, a decrease in the length of the α phase plates, and change in the proportion of α and β phases from 53% (SF 86) to 50% (SF 116) of the β phases. Differences in microstructure (column diameters, thickness, and length of α-phase plates), phase composition, microhardness, porosity at the bottom, and top of the samples were observed on all samples. The mechanical property analysis did not show a significant effect of SF on elongation, but an increase in SF from 86 to 96 resulted in an increase in ultimate tensile strength (UTS) of approximately 7%, whilst an additional increase to 116 resulted in a decrease in UTS of approximately 8.5% compared to SF 96. From the results, it can be seen that the microstructural and mechanical properties of the material strongly depend on the SF. Based on it, SF 86 can be considered as the recommended value for the manufacture of Ti-55511 alloy parts. [ABSTRACT FROM AUTHOR]

The Cu-Cr-Zr alloy has an important role in the domain of thermonuclear fusion and electronic applications. But due to their higher thermal conductivity and reflectivity, the laser powder bed fusion (LPBF) manufacturer faces many defect formations such as balling effects, spattering effects, and un-melted powders during the fabrication of Cu-Cr-Zr alloy. However, these defect formations can be reduced by analyzing and evaluating the interactions of parameters. In this research, a correlation of LPBF process parameters such as laser power (250, 350, and 450 W), scan speed (750, 850, and 950 mm/s), and hatching distance (0.05, 0.07, and 0.09 mm) was investigated to achieve defect-free Cu-Cr-Zr parts with reduced porosity and surface roughness with maximum nanohardness. The combined analytical approach based on integrated entropy and Deng's similarity validated the experimental study. Major defects such as cavity formation, lack of fusion between the layers, and improper melting of Cu-Cr-Zr powder particles were evident during the reduced energy density of around 100 to 200 J/mm3 during the adoption of a minimum laser power of around 250 to 300 W. The outcome shows that defect-free parts with reduced porosity of 0.88%, reduced surface roughness of 23.24 µm, and maximum nanohardness of 5.2 GPa were achieved during the optimal setting of 450 W laser power, 850 mm/s scan speed, and 0.05 mm hatching distance. LPBF Cu-Cr-Zr alloy with optimal combination offers 278.92 MPa in ultimate tensile strength and 11.69% in ductility. The optimal settings obtained from the experimental study are in greater agreement with the integrated entropy and Deng's similarity approach. [ABSTRACT FROM AUTHOR]

In friction stir welding, geometrical and motion features of the tool or pin greatly influence the interaction between the tool and workpiece as well as the resulting joint microstructure and mechanical properties. In order to enhance the material flow by optimizing the tool geometrical features, a new strategy was proposed in this study to introduce eccentric motion by offsetting the pin from the tool shoulder, and thin Al–Mg-Si aluminum alloy plates were friction stir welded by varying the pin eccentricity. The material flow and mixing characteristic were analyzed by optical microscope and tracer material method. The grain size and micro-texture of the stir zone were analyzed by electron backscatter diffraction. Uniaxial tensile tests and digital image correlation were conducted to evaluate the mechanical properties and observe the in situ strain evolution. The results show that pin eccentricity has a positive effect on promoting the material flow and grain refinement in the stir zone. The texture intensity was increased as pin eccentricity was introduced, and the dominant texture component converted from C {001} < 110 > (without eccentricity) to B / B ¯ {112} < 110 > when eccentric pin was used. However, no discerning change can be seen in the thermal history between samples. Despite the variation in softening of the stir zone with eccentricity, the ultimate tensile strength change was negligible. The average ultimate tensile strength reached approximately 198 MPa regardless of the pin eccentricity, and all joints fractured at the heat-affected zone. However, the softened stir zone caused by pin eccentricity resulted in an obvious increase in the joint elongation. It can be concluded that pin eccentricity significantly improved the material flow and grain refinement in the stir zone as well as enhanced the toughness of the weld joint. [ABSTRACT FROM AUTHOR]

Investigations of the rolling modes of plates from an experimental aluminum-magnesium alloy with a scandium content of 0.10–0.11 wt.%, corresponding to the chemical composition of the 1580 alloy, were carried out in laboratory and industrial conditions. It has been found that alloying of this material with scandium within the indicated limits leads to a significant grain refinement in the cast ingot and an increase in the strength properties of deformed semi-finished products. Based on the results of physical modeling of the rolling process, rational reduction modes are proposed, which made it possible to obtain deformed semi-finished products with the required level of mechanical properties. Based on the results of physical and computer modeling of the rolling process, rational reduction modes are proposed for pilot studies, which made it possible to obtain deformed semi-finished products with the required level of mechanical properties. At the same time, the power parameters of rolling did not exceed the allowable values of the force and rolling moment for the QUARTO 2800 rolling mill. To assess the formation patterns of the metal structure necessary to obtain high-quality plates, a metallographic analysis of the structure of cast and deformed semi-finished products from an experimental alloy was carried out. The results were used to test the reduction modes during sheet rolling and to adjust the casting parameters of experimental ingots. Annealing has practically no effect on the level of mechanical properties of plates obtained under production conditions in a hot-deformed state, while the ultimate tensile strength in the longitudinal direction is 388–389 MPa, the yield strength is 245–247 MPa, and the elongation to failure is 18.0–18.8%. After cold rolling, the plates have the following mechanical properties: ultimate tensile strength 413–414 MPa, yield strength 386–372 MPa, and elongation to failure 5.2–6.6%. Based on the results of the research, recommendations were formulated for the development and implementation of an industrial technology for rolling plates from alloy 1580 with a thickness of 31.5–45 mm from ingots with a thickness of 300–450 mm. [ABSTRACT FROM AUTHOR]

It is generally accepted in the field of friction welding that the parameters of rotary friction welding affect mechanical properties. Accurate input is crucial at each process stage, especially in smart factories that use automated machines to produce workpieces. The input for each parameter must be precise. This research proposes a prediction parameter for rotary friction welding for aluminium round bar AA6063, which uses the adaptive-network-based fuzzy inference system (ANFIS) method. The condition, which includes rotational speed, welding time, and friction pressure was used to input the membership function. The ultimate tensile strength of the weld joint was used for the output of ANFIS. The results show that prediction can contribute to industrial applications by determining which parameters can be adapted to the application control for the automatic rotary friction welding process in a Smart Factory. [ABSTRACT FROM AUTHOR]

Typical additive manufacturing (AM) processes for producing metal and ceramic parts are highly energy-consuming and expensive to install and maintain. On the other hand, material extrusion AM (MEAM) technologies are conventionally used to produce polymeric parts but only marginally to process metallic materials. A feasible alternative is to process polymeric filaments loaded with metal particles. Debinding and sintering processes are then required to join the metal particles and obtain the final parts. In recent years, highly filled metal filaments consisting of a polymer loaded with a high concentration of metal powder have been commercialized for this purpose. In this study, the printability of a commercial CuSn12 filament was investigated by evaluating the influence of the process parameters on the density, shrinkage, porosity, and mechanical properties of the additively manufactured samples using a low-cost desktop 3D printer. Parameters such as the flow rate and ironing had the greatest influence on the density of the green samples. The correct selection of these parameters may reduce shrinkage after sintering. Furthermore, the obtained bronze had a notable ultimate tensile strength (mean value of 107 MPa), high stiffness (E values range from 38 to 50 GPa), and a greater elongation at break (mean value of 13%) than that of cast bronze of the same CuSn12 type. In this case, the extrusion pattern and ironing had the most significant influence on the final mechanical performance. The study provides insights into the use of highly filled bronze filaments combined with MEAM to produce functional parts for engineering applications. [ABSTRACT FROM AUTHOR]

The objective of this work is to study the microstructure and the texture evolution in welded joint of X70 steel with duplex stainless steel joined by gas tungsten arc welding (GTAW) process and heat treated at 200 °C and 600 °C. Then, the microstructural evolutions are correlated to their hardness mechanical property. The characterization techniques used are optical microscopy, scanning electron microscopy, EDS, Vickers microhardness, tensile tests, X-ray diffraction, and electron backscatter diffraction (EBSD) technique. Two heat affected zones were observed in welded joint with different microstructures. Heat affected zone on the X70 steel side and another on the duplex stainless steel side. A solidification microstructure was observed in the fusion zone such elongated ferritic grains and a growth direction < 100 > was found. The most microstructural transformations were observed in the vicinity of the interface which connects the heat affected zone to the fusion zone either on the X70 steel side or on the duplex stainless steel side. The effect of heat treatment on the hardness of the welded joint was noticed in the side of the duplex stainless steel. The fusion zone is the hardest zone of the welded joint (309.4 Hv) and which is not affected by the applied heat. X-ray diffraction analysis did not reveal the formation of new phases after the heat treatments applied to the welded joint. The tensile tests have shown that the welded joint treated at 200 C presents the highest value of ultimate tensile strength (667 MPa). [ABSTRACT FROM AUTHOR]

This work is an attempt to fabricate aluminum (AA 5049) matrix composites (AMCs) reinforced with electrospun polyacrylonitrile (PAN) nanofibers and consisting of exfoliated graphite nanosheets (EGNS/PAN) by utilizing friction stir processing (FSP) to improve the mechanical characteristics of AA 5049. The electrospinning method was used for fabricating PAN and EGNS/PAN nanofibers. The average diameter of the electrospun PAN nanofibers is 195 ± 57 nm, and after EGNS incorporation is 180 ± 68 nm. Dynamic recrystallization was the main process in the microstructure evolution of the stir zone during the FSP with PAN and EGNS/PAN nanofibers. According to PAN and EGNS/PAN nanofibers were used in the FSP procedure, the grain size reduced as a result of the pinning effects. PAN and EGNS/PAN nanofiber reinforcement enhanced the hardness to 89 and 98 Hv, respectively. Also, the ultimate tensile strength was raised to 291 MPa and 344 MPa, respectively. Tensile strength and hardness of the stir zone increased during the FSP with PAN and EGNS/PAN nanofibers due to the higher density of the strengthening mechanisms of grain boundaries and dislocations. The mechanical characteristics of AA5049 can be enhanced by the procedure of incorporating nanofibers, making them an ideal choice for applications in the automotive and aerospace industries. [ABSTRACT FROM AUTHOR]

The poor formability of 7xxx series aluminium alloys represents the major limit to their actual use for automotive and aerospace applications. In the present study, the forming temperature effect on the mechanical, corrosion and anodization behaviours of the AA7075-T6 alloy is investigated. To this purpose, tensile tests at different temperatures, ranging from −100 to 300°C, were carried out at different rolling directions. A 6.6% increase of the ultimate tensile strength and a 28.6% increase of the uniform elongation were registered for the specimens deformed at the lowest temperature compared to highest ones. Further, the corrosion resistance of specimens deformed at ultimate tensile strength before and after anodization was increased of 85% and 95%, respectively, compared to the specimens deformed at 300°C. It was demonstrated that high deformation temperatures led to the coalescence of particles and precipitates as well as the decrease of dislocation density, which, in turn, decreased the mechanical and corrosion performances. On the contrary, the deformation temperature of −100°C was found to be the ideal one able to shorten the manufacturing process chain and improve material formability and durability during its in-service life. [ABSTRACT FROM AUTHOR]

This manuscript describes the study of density, porosity, microstructure, formation of phases, elemental distribution, tensile properties, fractography, microhardness, fracture toughness, and abrasion resistance of multi-layer deposition Ti-6Al-4V-5Ni alloy developed by μ-plasma metal additive manufacturing (μ-PBMAM) process for high temperature and high strength applications. It also presents comparison of these aspects with multi-layer depositions of Ti-6Al-4V alloy. Thermo-calc simulated phase diagram was used to decide at.% of Ni to be added to aerospace grade Ti-6Al-4V alloy. It found that adding 5% of Ni promotes grain refinement without forming C14 Laves phase and increasing the β-transus temperature. Optimum values of μ-plasma power and μ-plasma torch travel speed were identified by manufacturing single-layer depositions of Ti-6Al-4V-5Ni alloy thorough diluted depth, aspect ratio, deposition quality, deposition geometry, and deposition efficiency as the criteria to manufacture its multi-layer deposition. Results reveal that inclusion of nickel to Ti-6Al-4V alloy increased the volumetric percentage of β-Ti phase from 13 to 27% and refined grains of α-Ti and β-Ti phases which improved yield and ultimate tensile strength of Ti-6Al-4V-5Ni alloy by 13.4% and 17.8% respectively and reduced % elongation by 36% as compared to Ti-6Al-4V alloy. It changed fractured pattern from ductile to combined ductile and brittle fracture consisting of cleavage facets, voids, and larger size dimples. It increased % porosity, microhardness, fracture toughness, and abrasion resistance thus imparting Ti-6Al-4V-5Ni alloy more resistance to crack initiation and more restriction to movement of the dislocations. Vanadium and nickel contents in β-Ti phase of Ti-6Al-4V-5Ni alloy are 3 to 5 times and 21 to 25 times more than that its α-Ti phase, respectively. Findings of this work demonstrate that μ-PBMAM developed Ti-6Al-4V-5Ni alloy is useful for high temperature, high strength, and light weight applications in aerospace, space, automobile, and dies and mold industries due to promotion and grain refinement of β-Ti phase, improvement in microstructure, microhardness, yield and tensile strength, fracture toughness, abrasion resistance. [ABSTRACT FROM AUTHOR]

Large-scale industrial application of additively manufactured (AM) components in general, and specifically cold sprayed additive manufactured (CSAM), is limited due to the nature of this technology and the resulting product's porosity and embrittlement. To improve the final properties of additively manufactured material, many lengthy, complex, or expensive post-treatments have been proposed. Reducing the environmental impact, cost, and time required for additive manufacturing will allow for greater use in industrial applications. A novel thermomechanical treatment known as in situ electro-plastic treatment (ISEPT) is used in this study to treat CSAM Ti-6Al-4 V alloy known as grade 5 titanium. The Ti-6Al-4 V alloy has approximately three times the strength and hardness of commercial purity titanium (CP-Ti) with lower ductility and a dual-phase (α + β) microstructure that poses challenges during the CSAM process. Compared to CP-Ti, the results showed that CSAM Ti-6Al-4 V presented double the porosity and triple the number of ISEPT passes that presented ~ 2 µm ultra-fine grain microstructure. The ultimate tensile strength (UTS) of the ISEPT material was superior to that of CSAM Ti-6Al-4 V and increased from 184 to 1096 MPa with improved ductility rise from 1.1 up to 8.8%. Six ISEPT passes in air resulted in a slight increase in oxygen from 0.2% in the as-CSAM condition to 0.35%. Tensile properties of the ISEPT material were comparable to wrought Ti-6Al-4 V with 989 MPa UTS and 8.3% elongation. The ISEPT passes consolidated the CSAM (α + β) dual-phase Ti-6Al-4 V and allowed for the nucleation of equiaxed grains at the vicinity of former CSAM splat boundaries. The formation of lamellar colonies within the splat's inner regions was observed. The role of ISEPT conditions on the rapid elimination of porosity and the evolution of cold spray splat boundaries via dynamic recrystallization were discussed. [ABSTRACT FROM AUTHOR]

3D-printed artefacts are becoming more common, and the effect of printing parameters on their properties is key to their performance in applications. Although parameters like build orientation and raster direction are well-studied the effect of layer thickness is less well-known. This study determines the influence of layer thickness on the mechanical properties of polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) 3D printed specimens made with fused filament fabrication (FFF). Samples were printed with differing layer thicknesses and tensile tested according to ASTM D638. The study also found that when increasing the layer thickness the mechanical properties of the specimens for both ABS and PLA decreased. When it came to ultimate tensile strength, the effect of layer thickness on PLA was more significant than on ABS. Considering the mechanical properties as well as aspects such as printing time and simplicity of printing, an optimum print setting could be determined. The study found that PLA was more significantly affected by the change in layer thickness compared to ABS. [ABSTRACT FROM AUTHOR]

Intelligent additive manufacturing is the future direction, and changing parameters during manufacturing process is an effective measure to adjust the quality of parts. In this study, the stability behavior of the manufacturing process under three process strategies, low layer thickness fabrication (LLTF), high layer thickness fabrication based on the interval of the powder layer thickness (IPLT), and changing of layer thickness strategy (CLTS), was comparatively investigated. Multilayer experiments and mechanical properties experiments were performed during laser powder bed fusion, and the correlation between manufacturing quality and powder layer thickness was compared. By optimizing the process parameters, the surface quality of CLTS is similar to that of LLTF, and the value of minimum surface roughness can be between 22 and 23 μm. Only balling effect due to spattering and a small amount of porosity were found in the cross-section of CLTS. The relative density of most of the fabricated parts is higher than 99%, and the highest relative density is up to 99.99%. IPLT has longer and thicker martensite than LLTF, and the β-grain of CLTS is also coarser than LLTF. The tensile properties of CLTS are similar to those of LLTF, and the ultimate tensile strength, yield strength and elongation of CLTS are 1205 MPa, 1107 MPa and 6.8%, respectively. Due to the anisotropy of the LPBF, the horizontally constructed Ti–6Al–4 V specimens yielded higher strengths, while the vertically constructed specimens obtained better elongation. The fracture of the part is characterized by a mixture of brittle fracture, ductile fracture and quasi-dissociative fracture. The surface quality, relative density and mechanical properties of CLTS are similar to those of LLTF, while the forming efficiency is much higher than that of LLTF, which can reach 7.35 mm3/s. [ABSTRACT FROM AUTHOR]

Present study describes the effect of forge application under consideration of friction time on metallurgical and mechanical properties of friction welded joint for AISI 316. Direct drive friction welding (DDFW) has been utilized to obtain welded joints. Three friction times (6.5 s, 8.5 s and 10 s) with two directions for this study were used; the first direction was achieved by forge phase elimination and the second was performed under forge phase application. Macro-microstructure for welded joint, microhardness across the axial direction, tensile tests and tensile fracture morphology were investigated. As a conclusion, flash formation was decreased about 30% without forge compared to forge application. Thermo-mechanically affected zone (TMAZ) was extended in 8 mm at the interface without forge and highly plastically deformed zone (HPDZ) can be found at the interface after forge application. At shorter friction time for the two directions, ultimate tensile strength (UTS) and ductility were revealed closer to AISI 316. Hence, all tensile fractures were occurred adjacent to the interface at TMAZ, except in the shorter friction time after in forge application, the fracture was happened at the base metal, and that was confirmed with the fracture morphology which has the same character of AISI 316. [ABSTRACT FROM AUTHOR]

Laser welding of Al-Si-coated steels for hot stamping in automotive applications is problematic due to the mixing of the coating layers inside the molten pool that weakens the resulting weld seam. In this case, the most common welding procedure to overcome this issue consists in removing the Al-Si layer through laser ablation prior to the joining. This method continues to be the most widely used by major producers of tailor welded blanks, although in situ ablation of the Al-Si coating can be costly and time consuming. In this work, a novel approach consisting in joining as-received (i.e., not decoated) materials using a filler wire and an innovative variable energy distribution laser optics is introduced and tested on tailor welded blanks made of 22MnB5. Tensile tests of specimens obtained from a 33 full factorial design of experiment have shown an average value of ultimate tensile strength of 1523 MPa, which is much higher than the one usually observed in as-received welded then hot-stamped conditions and aligned with hot-stamped base material values. Hardness test results (494–543 HV0.5) were in the typical hot-stamped base material range of values as well, while SEM–EDS analyses detected no ferrite inclusions inside the fusion zone. Variations of the main process parameters have been considered on an iso-thickness and iso-material configuration, empirically demonstrating the stability and reliability of the proposed methodology as well as its suitability for production purposes. [ABSTRACT FROM AUTHOR]

Friction surfacing (FS) is a solid-state layer deposition process for metallic materials at temperatures below their melting point. While the bonding of the deposited layers to the substrate is proven suitable for coating applications, so far the mechanical properties of additively manufactured stacks have not been systematically investigated. In particular, the effect of successive deposited FS layers, i.e., repetitive thermo-mechanical loading, on the interface properties as well as anisotropy and strength of the deposited stack is unknown. For this purpose, the mechanical properties of FS deposited multi-layer stacks from dissimilar aluminum alloys have been investigated, characterizing layer-to-layer as well as layer-to-substrate bonding interfaces via micro-flat tensile testing. Furthermore, directional dependencies in the stack and failure mechanisms are analyzed. The results show a homogeneous, fine-grained microstructure with average grain sizes between 4.2 and 4.6 μ m within the deposited material. The resulting tensile properties with no significant directional dependency present an ultimate tensile strength between 320 and 326 MPa exceeding the strength of the AA5083 H112 consumable base material. No difference was obtained in terms of layer-to-layer or layer-to-substrate interface strength. Furthermore, homogeneous hardness was observed within the deposited structure, which is in the range of AA5083 base material's hardness of 91 HV. The results indicate that the FS process in conjunction with the material used is suitable for additively generated structures and highlight the potential of this solid-state layer deposition technology. [ABSTRACT FROM AUTHOR]

This study investigated the print homogeneity of Ti-6Al-4 V alloy parts, when printed over a large build area of 250 × 250 × 170 mm3, using a production scale laser powder bed additive manufacturing system. The effect of part location across this large build area was investigated based on printed part porosity, microstructure, hardness, and tensile properties. In addition, a Hot Isostatic Pressing (HIP) treatment was carried out on the as-built parts, to evaluate its impact on the material properties. A small increase in part porosity from 0.01 to 0.09%, was observed with increasing distance from the argon gas flow inlet, which was located on one side of the build plate, during printing. This effect, which was found to be independent of height from the build plate, is likely to be associated with enhanced levels of condensate or spatter residue, being deposited at distances, further from the gas flow. Despite small differences in porosity, no significant differences were obtained for microstructural features such as prior β grain, α lath thickness, and phase fraction, over the entire build area. Due to this, mechanical performances such as hardness and tensile strengths were also found to be homogenous across the build area. Additionally, it was also observed based on the lattice constants that partial in-situ decomposition of α ′ → α + β phases occurred during printing. Post HIP treatment result showed a decrease of 7 and 6%, in the yield strength (YS) and ultimate tensile strength (UTS), respectively, which was associated with a coarsening of α lath widths. The potential of the laser powder bed system for large area printing was successfully demonstrated based on the homogenous microstructure and mechanical properties of the Ti-6Al-4 V alloy parts. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) is a fabrication process based on the addition of material by layers and has shown several advantages against other manufacturing processes, such as low cost and possibility of manufacturing parts with complex geometries. However, the additive manufacturing can change the properties of the workpiece due to the strategy of multilayer deposition, which can cause changes in the microstructure of the deposited material. In this sense, this work aimed to evaluate the chemical composition, microstructure, and mechanical and electrochemical behavior of the 316L stainless steel manufactured by wire and arc additive manufacturing (WAAM), comparing it with a sample of the same alloy in the annealed condition, trying to understand how the different layers interfere in the final behavior of the material. The results indicate that the microstructure of the deposited material is different with the presence of ferrite in an austenitic matrix. Two regions whose microstructure had different morphologies were also identified in the WAAM alloy. In the region close to the fusion line between the deposited layers, the austenite grains are smaller, about 5 μm wide, against 10 μm of the grains in the area most to the center of the layers. This microstructural change caused an irregular microhardness profile, with an average of 276 HV, higher than the 190 HV of conventional material. It was also observed that the WAAM process caused a decrease in the yield strength (YS) (23%) and elongation (78%) of the alloy and a slight increase in the value of ultimate tensile strength (UTS) (9%); however, it still meets the minimum requirements for most industrial applications required for the material studied (min. UTS 485 MPa, min. YS 170 MPa, and min. elongation 35 MPa). Moreover, the electrochemical results in simulated seawater solution indicate that the corrosion potential of the deposited sample is like that of the conventional specimen (about 0.24 V), with the potential passivating of the first to be superior to that of the second, respectively, 0.640 V and 0.560 V. [ABSTRACT FROM AUTHOR]

As one of the important additive manufacturing techniques, selective laser melting (SLM) has shown great advantage in the production of metal matrix composite components with complex geometry. However, the layer-by-layer manufacturing procedure causes a nonnegligible thermal accumulation and cycling. Thus, the SLM-deposited component always presents gradient microstructure and mechanical properties. In this work, the dense TiB2p/2024Al composite prepared by SLM was employed to investigate the heat-induced microstructure evolution and mechanical properties. The as-deposited composite presents a uniform distribution of TiB2 reinforced particle in α-Al matrix with an oriented < 100 > texture α-Al dendrite microstructure. The yield strength (YS), ultimate tensile strength (UTS), and the elongation of as-deposited sample increase from 230.06 MPa, 302.52 MPa, and 4.49% to 244.17 MPa, 365.36 MPa, and 11.48% from the bottom to top regions. According to the TEM results, this phenomenon is attributed to the high cooling rate induced low content of θ-Al2Cu phase at the bottom of the sample. In addition, agglomeration of the TiB2 particles due to the insufficient convention is responsible to the poor elongation at the bottom of the sample. After the solid solution and aging heat treatment (T6), thanks to the uniform distribution of S strengthening phases, this gradient in microstructure and mechanical properties in the deposit can be eliminated, and the deposit presents higher YS, UTS, and a lower elongation of 380.23 MPa, 421.50 MPa, and 3.14%. [ABSTRACT FROM AUTHOR]

This research aims to investigate the effects of as-casted and proposed in situ heat-treated squeeze casting of Al-3.5 % Cu alloy. The effects of squeeze pressure, melt temperature and die temperature on ultimate tensile strength, percentage elongation and hardness were modelled and analysed for as-casted and in situ heat-treated squeeze casting using the Box-Behnken design. Response surface methodology was used for experimental design, empirical modelling and analysis. Adequacy and validation of the developed models were verified using ANOVA and confirmation experiments, respectively. The results revealed squeeze pressure as the most significant input variable followed by die temperature under as-casted and in situ heat-treated squeeze casting conditions. The comparative analysis suggested in situ heat-treated squeeze casting conditions as the best alternative which resulted in 7.9~11, 6.7~25.7, and 2.2~7.7 % improvement for ultimate tensile strength, percentage elongation and hardness, respectively. A considerable increase in mechanical properties provided a great evidence to reveal a new technique for foundry men to enhance the quality of squeeze casted Al-Cu alloys. Furthermore, the empirical model will aid practitioners to predict the desired mechanical properties prior to examination. [ABSTRACT FROM AUTHOR]

Dissimilar weldments of AISI 316 and Monel 400 are extensively used in boiler feed water heaters where the weld roots are exposed to high pressure and hot corrosive environments. In this research, metallurgical and mechanical properties of dissimilar weldments of AISI 316 and Monel 400 obtained by pulsed current gas tungsten arc welding (PCGTAW) and constant current gas tungsten arc welding (CCGTAW) processes were compared. The heat input rate and filler wire were same in both welding techniques. Metallurgical properties are studied by employing optical microscope (OM) and scanning electron microscope (SEM). Mechanical properties of dissimilar weldments are determined by tension test and Vickers hardness. The metallurgical study has revealed fine grain structures with clear grain boundaries at the heat-affected zone in PCGTAW weldment. The ultimate tensile strength in PCGTAW and CCGTAW weldments was observed as 554 and 542 MPa, respectively. The ratio of yield strength to ultimate tensile strength is higher in PCGTAW weldment than CCGTAW weldment. The weldment developed by using PCGTAW technique has shown a higher microhardness value at HAZ of both the base metals than the weldment developed in CCGTAW technique. [ABSTRACT FROM AUTHOR]