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Determining the mechanical characteristics of additively manufactured materials has been an active topic of research in recent years. Many studies have been performed analyzing the impact of different 3D print parameters on the tensile properties of the printed material. However, compared to typical metals and polymers, there is no widely adopted standard for testing additively manufactured polymers. Consequently, the test results reported by the researchers in this field exhibit high amounts of variability between studies. A set of consistent experiments across five different printing parameters including build orientation, raster orientation, infill type, infill density, and layer thickness was carried out in the present paper. The results were analyzed to look at trends between the tested variables and the yield strength and elastic modulus of the resultant additively manufactured polyethylene terephthalate-glycol (PETG). Build orientation, raster orientation, infill type, and infill density all showed strong relationships with the tensile properties. Layer thickness showed little variation across the typical range for a given extrusion width. Previously developed experimental models were also checked and showed that even small variations in other parameters such as raster gap or extrusion factor could create significant enough variation to make the model inaccurate for a specific scenario. [ABSTRACT FROM AUTHOR]

Taguchi's design of experiment (DoE) and the grey relational analysis are used to optimise fused filament fabrication (FFF) parameters for the tensile strength and modulus of toughness (MoT) responses of a recycled polylactic acid (Reform-rPLA). The paper investigates the influences of the infill geometry, infill density, infill orientation, nozzle temperature and infill speed on the mechanical properties using the L 18 orthogonal array that is based on the 2 1 × 4 3 factor levels and 3 experimental repetitions. The output responses are first studied individually and combined as a multi-response optimisation using the grey relational analysis method. In the strength optimisation, the infill orientation and infill density are statistically significant with P-values α less than the 0.05 criterion. Similarly, the analysis of variance (ANOVA) for the MoT showed that infill orientation and infill geometry are statistically significant. For the multi-response optimisation, only the infill orientation is statistically significant. The mean response analyses identified factor levels that led to optimum strength and MoT responses. The confirmation tests are in good agreement with the response predictions. Using the first three influential factors, multiple variable linear regression models were developed. The predictive models showed average errors of 7.91 % for the tensile strength and 8.6 % for the MoT. [ABSTRACT FROM AUTHOR]

Activating fluxes (AF) can be applied in the welding process to improve the morphology, microstructure, and mechanical properties, such as hardness, tensile strength, and yield strength. Regarding the published research on AF application in Tungsten Inert Gas (TIG) welding, there are limited studies concerning the Gas Metal Arc Welding (GMAW) process. This gap in research has prompted investigations aimed at determining the influence of AF during the GMAW process. The purpose of this paper is to apply three types of AF (SiO2, TiO2, and CaCO3) in 316L stainless steel GMAW processing and analyze their influence on the weld bead geometry, hardness, and microstructure. The results showed that the highest penetration and the smallest width can be obtained using TiO2 as AF while the highest reinforcement can be obtained by CaCO3 as AF. This also indicated a possible significant increase in AF addition after-welding hardness, which may be caused due to the microstructure changes. The microstructure observation revealed that the welding area without AF was mainly composed of austenite and the addition of AF increased the welding temperature, which caused the martensite structure to be found in these samples. The heat treatment was introduced to reduce the hardness since large and uneven hardness would bring negative consequences such as brittleness. The after-HT analysis showed that HT can reduce the hardness effectively and improve the uniformity of the whole weld bead. Additionally, it was found that samples with AF were more sensitive to HT. This study concludes that AF can be applied in the GMAW welding process and influence the weld bead significantly. [ABSTRACT FROM AUTHOR]

This paper explores the potential to hot stamp third-generation steels, in this case, a 980 MPa grade, while retaining or improving on the as-received microstructure, in particular the retained austenite (RA) fraction, and corresponding strength and ductility. Three classes of thermomechanical processes were investigated using a thermo-mechanical simulator system (Gleeble 3500). The first two processing routes considered a quenching and partitioning process starting from either a fully austenitic condition prior to quenching, designated the "Q&P" process, or an inter-critical partial austenitic condition, designated the "IC Q&P" process. In the two simulated Q&P processes, the samples were quenched to a predetermined temperature and then immediately transferred to a partitioning furnace. In the third processing route, designated the "Q&T" process, the samples were partially austenitized and then quenched to room temperature, followed by a tempering process to restore ductility. The conventional Q&P process resulted in excessive martensite formation, with high hardness and low ductility. The Q&T process produced a tempered martensite microstructure with hardness equivalent to the as-received sheet but with lower elongation and bendability. The IC Q&P heat treatment process increased the amount of retained austenite compared to the as-received sheet which translated into a higher yield strength, total elongation, and v-bend fracture angle. The IC Q&P ultimate tensile strength was approximately 8% lower than that of the as-received material. A sensitivity study was conducted to evaluate the influence of variations (± 25 °C) in the intercritical austenitization temperature, quench temperature, and partitioning temperature on the resulting microstructure and microhardness. The final mechanical properties were observed to be relatively independent of these process variations, indicating that the IC Q&P hot stamping process appears to be robust. [ABSTRACT FROM AUTHOR]

In order to manufacture functional parts using filament deposition modelling (FDM), an understanding of the machine's capabilities is necessary. Eliciting this understanding poses a significant challenge due to a lack of knowledge relating manufacturing process parameters to mechanical properties of the manufactured part. Prior work has proposed that this could be overcome through the creation of capability profiles for FDM machines. However, such an approach has yet to be implemented and incorporated into the overall design process. Correspondingly, the aim of this paper is two-fold and includes the creation of a comprehensive capability profile for FDM and the implementation of the profile and evaluation of its utility within a generative design methodology. To provide the foundations for the capability profile, this paper first reports an experimental testing programme to characterise the influence of five manufacturing parameters on a part's ultimate tensile strength (UTS) and tensile modulus (E). This characterisation is used to train an artificial neural network (ANN). This ANN forms the basis of a capability profile that is shown to be able to represent the mechanical properties with RMSEP of 1.95 MPa for UTS and 0.82 GPa for E. To validate the capability profile, it is incorporated into a generative design methodology enabling its application to the design and manufacture of functional parts. The resulting methodology is used to create two load bearing components where it is shown to be able to generate parts with satisfactory performance in only a couple of iterations. The novelty of the reported work lies in demonstrating the practical application of capability profiles in the FDM design process and how, when combined with generative approaches, they can make effective design decisions in place of the user. [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]

Quantitative quality characteristics of additive manufactured parts are influenced by parameters selected in the preparation process (pre-process), especially in the material extrusion process. As a result, a prediction of the tensile strength of manufactured parts is hardly possible, which significantly reduces the usability of the process. In this paper a neural network approach is used to predict the tensile strength during the pre-process. The parameters investigated are print speed, number of shells, layer thickness, nozzle temperature and infill density. A prediction with a mean absolute percentage error (MAPE) of 2.54% could be achieved for randomly generated process parameters using a training data set of 243 samples. This exceeds the best prediction accuracies of the current literature which is between 2.56 and 3.34%. However, this research is particularly different in that, unlike the existing literature, the developed prediction models were tested with untrained random parameter values in a properly conducted test. With a data reduction to a data volume of 32 samples the used approach achieved already a MAPE of 4.15%. The neural network approach outperformed a multiple linear regression even at low training data volume. This publication differs from previously published research activities due to the achieved prediction accuracies on random parameter sets, the number of investigated parameters and the sample size. Users are provided with an algorithm and its procedure to predict the tensile strength which can be adapted to the respective application with the help of company data. [ABSTRACT FROM AUTHOR]

Inconel718 maintains excellent mechanical properties at high temperatures of 700 ℃ and has a wide range of applications in aerospace, high-performance turbines, and other fields. However, the use of improper laser process parameters makes the Inconel718 obtained by the directional energy deposition method have poor performance and defects, and there are currently fewer studies on the regulation of the mechanical properties of the preparation of Inconel718 by directed energy deposition. In this paper, the influencing regulation of laser process parameters of laser power, scanning speed, hatch spacing, layer thickness, and forming direction on the microstructure and mechanical properties of Inconel718 prepared by directional energy deposition is investigated by single-factor test method. The mechanical properties of Inconel718 obtained by directional energy deposition and forge are compared. The results show that, among the five laser process parameters, the laser power and forming direction have significant effect on the mechanical properties of Inconel718 obtained by directional energy deposition, while the scanning speed, scanning spacing, and layer thickness have less influence on its mechanical properties. Compared with Inconel718 prepared by ordinary forge, the tensile strength of Inconel718 obtained by directed energy deposition is reduced by 7.64%, the hardness is increased by 23.55%, the impact strength is reduced by 17.6%, and the plasticity is reduced obviously. Good mechanical properties can be reached from the Inconel718 obtained by the directional energy deposition method. [ABSTRACT FROM AUTHOR]

In this paper, a disk laser welding was developed to join 3-mm thin-Sect. 30Cr3 ultra-high-strength steel which was widely used in aerospace. The microstructure and mechanical properties of welded joint were investigated in detail. The results indicated that the recommended laser linear energy range were between 150 and 165 J/mm to guarantee that the melting width was up to 1 mm as well as less oxidation, spatter, and depression on the weld. Meanwhile, for the as-welded (AW) condition, the base metal (BM) consisted of ferrite matrix with distributing small spherical carbides, also known as spherical pearlite. While, the fine grained region, coarse grained region, and weld metal were all composed of martensite. However, the partially transformed region mainly consisted martensite with a little of spherical pearlite. Meanwhile, the average grain sizes of weld metal, HAZ, and base metal were 1.3 μm, 1.5 μm, and 1.8 μm, respectively. However, for the post-weld heat treatment (PWHT) condition, the whole welded joint was all composed of tempered martensite, and the average grain size of welded joint was about 1.7 μm. The tensile strength of the welded joint was higher than that of the base metal both in the AW and PWHT condition as all the fracture with shrinkage occurred in the BM of the specimens. Additionally, the average yield strength of the AW and PWHT are about 600 MPa and 1700 MPa, respectively. [ABSTRACT FROM AUTHOR]

Manufacturing based on the selective laser sintering process has received a lot of attention in recent years because of its ability to produce complex parts without the need for support structures. Although this technology was created for the manufacture of prototypes, it is now applied to the manufacture of finished products. For this reason, the mechanical behavior and strength of the printed parts are of paramount importance. These are highly dependent on the process parameters which, if set at the right levels, can give better results. This paper focuses on the experimental study of the effect of four SLS parameters, such as laser power, scanning speed, layer thickness, and scan spacing on tensile strength, modulus of elasticity, and elongation at break. The specimens were printed at three angles, namely, 0°, 45°, and 90°, in order to study the influence of the orientation of the parts on their tensile properties. One hundred thirty-five polyamide 12 specimens were printed according to Taguchi's L9 table. Subsequently, a series of tensile tests were conducted; the results obtained allowed to determine the strength and stiffness of the examined specimens. Then, validated regression models were generated. The obtained results will be interesting for a future development of SLS parts with better tensile strength, higher stiffness, and better ductility. [ABSTRACT FROM AUTHOR]

To seek a fundamental understanding for further improving the Ti-6Al-4 V alloy utilization of cross-wedge rolling (CWR) and the comprehensive mechanical properties of shaft parts, the effect of the CWR processing parameters on the microstructure evolution of Ti-6Al-4 V alloy shaft preform is studied in this paper. An Arrhenius-type microstructure evolution model was employed and implemented into the finite element software DEFORM-3D. The average grain size and dynamic re-crystallization (DRX) volume fraction distribution in the α + β two-phase region and the β single phase region under different rolling temperature, roller rotating speed, and area reduction were analyzed, respectively. It is found that the microstructure evolution of Ti-6Al-4 V alloy is affected by CWR processing parameters. Meanwhile, the corresponding CWR metallographic experiments were conducted to verify the reliability of the FE-simulation results. The difference in average grain size in the β phase region between simulation and experimental is ranged from 5.77 to 18.56%. However, the agreement of the process parameter effect on dynamic recrystallization in the α + β two-phase region is reasonably well. The evenly distributed microstructure can be found as the area reduction rate of 50%, rolling temperature of 950℃ and the speed of 5 r⋅min−1 were employed. In addition, the higher tensile strength of Ti-6Al-4 V alloy shaft preform increased by 18.57% and the plasticity enhanced significantly due to smaller grain size and α + β two-phase microstructure can be obtained by CWR under optimized processing conditions. [ABSTRACT FROM AUTHOR]

This paper investigates the mechanical properties of AA2024 joints welded using the Friction Stir Welding (FSW) process, with a particular focus on comparing joints made with and without the inclusion of a commercially pure copper sheet between the edges being welded. The study aims to understand the influence of weld heterogeneity on the mechanical properties of FSW joints. Various joints were fabricated with a copper interlayer, and optimal process parameters—rotational speed, advancing feed, and tool geometry—were identified. Mechanical tests, including Rockwell B and Vickers hardness (HV) tests, as well as tensile tests, were conducted on both homogeneous and heterogeneous joints. The results showed that the presence of copper significantly affected the hardness distribution, particularly in the weld nugget. Heterogeneous joints demonstrated a notable increase in HV at the nugget and a reduced weld-affected area on both the advancing and retreating sides. The study found a strong correlation between process parameters, tool geometry, and the Ultimate Tensile Strength of the joints. Optimal mechanical properties were achieved in heterogeneous joints welded at 800 rpm and 40 mm/min with an 18 mm tool, resulting in a joint efficiency of 73%. These parameters differed significantly from those optimized for homogeneous joints, which were 1200 rpm and 100 mm/min with a 16 mm tool. It was also observed that exceeding 1000 rpm in rotational speed and 70 mm/min in feed speed is not advisable for heterogeneous welds. Future research should explore varying amount of copper and other materials, as well as different interposition methods, to further understand their effects on the mechanical properties of FSW joints. [ABSTRACT FROM AUTHOR]

Lightweight bent aluminum profiles are widely utilized in transportation fields. In this paper, the torsional channel self-bending extrusion process (TCSE) was adopted to machine AA6063 bent aluminum profiles in a single operation to verify the process's feasibility. Effects of extrusion parameters on the curvature, microstructure, and mechanical properties of the profiles were researched, and the extrusion process was simulated. The results show that the extruded profiles had good curvature stability. The grains were equiaxed in the cross longitudinal section, and the grain size at the outside diameter (OD) position was smaller than the inside diameter (ID) position. When the difference in deformation temperature at the OD edge was above 31 K, a smaller peripheral coarse grain (PCG) layer was formed at the OD edge with a thickness of about 400 μm, resulting in reduced hardness. The Mg2Si particles served as the main strengthening phase, which increased in number and decreased in size with increasing billet temperature and extrusion speed. Increasing the billet temperature and speed improved the mechanical properties of the material, with an increase in average hardness of 55.9% and 19.5%, and ultimate tensile strength (UTS) of 12.5% and 7.1%, respectively. By comprehensively considering the factors of extrusion load, microstructure, and mechanical properties, the optimum bent profile for different curvatures was determined. When a large curvature (≥328.67 mm) was required, it was preferred to increase the billet temperature. When a smaller curvature (≤328.67 mm) was required, it was advisable to increase extrusion speed. [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 aim of this paper is to investigate welded joints of high-strength steel S960 QL manufactured by using three different welding technologies, namely the electron beam, the laser beam, and the metal active gas (MAG) technologies. The experimental part included tensile strength evaluation, microstructural analysis of welded joints, and hardness measurement. Welded joints (WJ) have consisted of the identical steels and the identical thickness (10 mm). Destructive tests confirmed that welded joints are characterized by the tensile strength similar to the base material. Upon further observation, we can conclude that microhardness was characterized by the lowest value in the softening zone (SZ) and the highest value in the hardening zone (HZ). The degree of softening was 11% for the electron welding, 13% for the laser welding, and up to 27% for the conventional MAG welding. This also corresponds with the size of the SZ, which was the widest in welds made with the MAG technology. The laser beam weld produced up to 50% lower heat-affected zone (HAZ) compared to the conventional MAG technology. In case of the electron beam, this number is even higher. On the contrary, highest hardness was observed for the electron beam technology, where the hardness in the hardening zone increased by up to 40% when compared with the base material. Tests show the possibility of production of reliable welded joints, which meet the complex requirements for lifetime and quality (according to the standard EN 6520–1 focusing on defects categorization and EN 5817 dealing with defects tolerance). [ABSTRACT FROM AUTHOR]

This paper investigates the effects of hygrothermal aging on PA6 filaments used as raw material in fused filament fabrication (FFF). The filaments were subjected to various aging conditions to evaluate their physicochemical and thermomechanical properties. The results show that water was uniformly absorbed at all aging temperatures, although the kinetics of absorption varied. The introduction of water caused an increase in chain mobility, resulting in a decrease in the glass transition temperature, crystallinity, Young's modulus, tensile strength, and yield strength. These changes in properties followed a consistent trend, with an initial rapid decrease followed by stabilization at a minimum value common to all temperatures. Notably, elongation at break increased sevenfold at the highest temperature. Compared to samples printed with unaged filaments, those produced with aged filaments exhibited a decrease in mechanical properties. [ABSTRACT FROM AUTHOR]

Geometric errors of parts affect not only the geometric deviations of the products obtained by assembling these parts through glue but also the mechanical strength of these products. Therefore, it is needed to investigate the relationship between geometrical deviations and the mechanical strength of assemblies due to a bonding process. In this work, the influence of adherends' misalignment on the 3- and 4-point flexural strength of a single-lap joint was investigated. A numerical model that considers the joint's geometric errors was developed and applied to different cases with different values of adhesive thickness and adherends' misalignment. The obtained results show that adherends' misalignment affects the performance of SLJs; in fact, the maximum load is always lower when SLJs have an adherends' misalignment. The numerical results were validated experimentally. The original contribution of the paper was to demonstrate numerically and experimentally the relationship between adherends' misalignment and flexural strength of single-lap bonded joints. [ABSTRACT FROM AUTHOR]

In this paper, the effects of strain rate on the mechanical properties of DP780 were analyzed by quasi-static tensile test and Hopkinson bar test; Johnson-Cook constitutive model with high strain rate was established. Based on ANSYS/LS-DYNA finite element program, the finite element simulation of electromagnetic forming process of high-strength steel sheet under the action of driving plate was realized, and the influence of various process parameters on the forming height was studied. The results showed that the yield strength and ultimate tensile strength of the material increased with high strain rate, and DP780 high-strength steel had certain strain rate sensitivity. The drive sheet receives the maximum magnetic field force near the outermost two-turn coil. The deformation of high-strength steel plate mainly occurs under the action of impact inertia. The peak forming height increases with the rise of discharge frequency. The increase of the thickness of the drive sheet can reduce the forming efficiency. [ABSTRACT FROM AUTHOR]

This paper describes the successful repair of a crack occurring at a centrifugal pump housing, by applying the Metalock joining procedure. The crack was analyzed and the appropriate Metalock key was selected for the repair. The selection of the most appropriate Metalock joining key was based on empirical parameters and on the tensile test results. Final results of the repair were checked by a pressure test. Furthermore, this paper closely describes the applied Metalock joining procedure, the appearance of joint macrostructure, tensile properties of the selected Metalock repair key, and the appearance of the repaired centrifugal pump housing. [ABSTRACT FROM AUTHOR]

Ultrasonic welding is increasingly used in industry. In this paper, the influence of ultrasonic welding parameters (USW) on the joint strength and quality was analysed. The properties of the USW joints depend on many factors. The work focuses on the influence of the technological parameters and the surface properties of welded EN Cu-ETP copper sheets with a thickness of 1 mm. The impact of the process parameters, such as welding time, pressure, vibration amplitude and the surface roughness on the lap shear strength and the metallographic weld properties was analysed. The welding energy for each variant was also determined. The research was conducted on the basis of a full factorial design of experiments. The optimal process parameters were determined to obtain high-quality joints in terms of strength and weld quality. Based on the presented experimental study, it was demonstrated that the ultrasonic vibration amplitude has the greatest impact on the joint strength. A surface preparation with acetone resulted in the highest tensile strength and welding energy and, making any additional surface treatment prior to welding unnecessary. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) is a progressive technology which holds promise for manufacturing of heat resistant super alloys. One of the most productive methods is wire arc additive manufacturing (WAAM). In this article, an alternative WAAM strategy is investigated. Experimental clads and material tests were performed to evaluate the material properties obtained through a cold metal transfer (CMT) discontinuous WAAM of Inconel 625 alloy. Using the modern terminology of Fronius Gmbh this method is called CMT cycle step. The difference is that it is automatically controlled by the welding source. CMT discontinuous WAAM has lower productivity and a higher consumption of shielding gas. However, it excels in low heat input and precise material cladding in comparison with a standard CMT continuous WAAM. It enables fabrication of finer details even on thin-walled components or in sections with problematic heat dissipation. Samples manufactured using this strategy were also compared with samples manufactured through a standard CMT continuous WAAM. Two sets of manufactured samples were thus tested. The following material tests were performed: (i) metallographic analysis, (ii) x-ray tomography, (iii) SEM analysis, (iv) hardness, (v) tensile strength (20 °C, 650 °C) and (vi) pin-on-disc (20 °C, 650 °C). The results show that the CMT discontinuous WAAM led to improved material properties in the Inconel 625 samples. Ultimate tensile strength improved by 15% at 20 °C and by 4% at 650 °C. Wear resistance at 650 °C was about two times higher. This paper concludes that the CMT discontinuous WAAM for Inconel 625 is definitely suitable for manufacturing of complex shapes, fine details and thin-walled components. [ABSTRACT FROM AUTHOR]

Adhesive work holding can be used to minimize clamping distortion and provide greater access to a work piece during machining. This paper proposes shear and tensile strength criteria to evaluate the work holding strength of adhesive grippers and definition of a strength safety coefficient of adhesive grippers. It also demonstrates a case study of work holding design with an UV adhesive for a grinding process based on a strength criteria explained in the paper. A test rig has been designed and manufactured to assess the capability of an adhesive work holding material. Tests include measurement of strength and repeatability of adhesion under different film thicknesses, curing times and pre-cleaning methods. The test shows the strength repeatability is less than ± 20%, which is good enough for many work holding applications. A shear-tensile combined strength can be evaluated by the strength sphere in a fixture design of a specific part geometry for production by the combined safety coefficient. Following the test rig assessment, a fixture has been designed with 3 grippers to demonstrate the adhesive for a grinding process with a simple part geometry. The method has a high potential for application in industry, and is not limited to the given part geometry and machining method. The grinding test shows that the adhesive work holding is strong enough for the application and that similar results can be expected for milling and turning with a good gripper arrangement. [ABSTRACT FROM AUTHOR]

This paper presents the development and characterization of cost-effective short Kevlar fiber reinforced nylon composite filaments. The effect of Kevlar fiber content on the tensile properties and the fiber distribution morphology was explored. A small amount of short Kevlar fiber was twin-screw compounded with nylon to study the reinforcing effects. Optical microscopy was used to investigate the morphology and the fiber distribution in the nylon matrix. The tensile strength of Kevlar composites increased to 90 MPa and 99 MPa at the fiber content of 1 wt% and 3 wt%, respectively, compared with the tensile strength of 84 MPa for pure nylon. As the fiber content increased from 0 to 3 wt%, the tensile modulus increased from 3.28 to 3.77 GPa. The optical microscopy and SEM images indicate that the twin-screw compounder with a proper screw configuration could disperse and distribute the Kevlar fibers uniformly in the nylon matrix. Statistically, this study demonstrates that the tensile strength and tensile modulus of nylon filament can be effectively enhanced with the addition of small amount of Kevlar fiber (i.e., less than 3 wt%), without sacrificing the ductility. [ABSTRACT FROM AUTHOR]

Remelting and remolding characteristics of thermoplastic resin make the carbon fiber-reinforced polyether-ether-ketone (CF/PEEK) composite process unique recyclability and reusability, while thermal characteristics play the crucial mechanism. This paper presents a comprehensive investigation on thermal characteristics of CF/PEEK drilling in terms of the heat transfer mechanism, crystallinity, and hole making performance. Crystallinity is introduced to quantitatively evaluate the change of material performance for CF/PEEK drilling where the crystallinity is positively correlated with tensile strength. Parameter analysis shows that the increased spindle speed leads to the increase of drilling temperature, crystallinity, and slightly deduces the tensile strength of CF/PEEK. The heat transfer curve of CF/PEEK drilling was first obtained and it is found that the heat transfer experiences three stages, namely steady rising, slow falling, and fast falling stage. Crystallinity comparative analysis between the hole wall and chips reveal that heat transfer effect dramatically affects the crystallinity when the drilling temperature exceeds the glass transition temperature (142 °C). Further, high temperature-induced PEEK smearing effect reduces the fiber exposure and surface roughness of hole wall but increases the crack appearance. The work provides important guidance for the high quality drilling of CF/PEEK composites from the point of view of the thermal characteristics. [ABSTRACT FROM AUTHOR]

Titanium alloy extruded profiles with complex cross-section are usually used to manufacture special-shaped structural parts in the aviation industry. In this paper, a Ti-6Al-4 V profile with asymmetric Y shape was manufactured by a direct extrusion process. A comparative study was conducted at the different lubrication conditions, in which the different process deformation mechanisms, resulting microstructures, and mechanical properties of profiles have been investigated by finite element simulation and a series of experiments, i.e., scanning electron microscope (SEM) and electron backscatter diffraction (EBSD). It was revealed that the metal flow is blocked at the narrow die orifice due to the deterioration of lubrication, resulting in the continuous shrinkage defect. The metal deformation coordination mechanism becomes gradually significant due to poor friction contact, which promotes the internal stress in the cross-sectional center to transfer outward to balance the friction at the edge of the orifice, resulting in the reduction of the effective strain in the center. The heat generated by friction weakens the heat exchange behavior between the metal and the die, which helps the profile retain a more uniform temperature field. In the sectional center of the profiles made from the two different lubrications, extrusion with good lubrication results in greater grain/colony refinement due to greater effective strains, and a slightly greater dislocation density was found due to the uniform deformation. The tensile tests revealed that compared with poor lubrication, due to the improvement of Hall–Petch strengthening and dislocation strengthening in the cross-sectional center with good lubrication, the variation range of yield strength and tensile strength is reduced to 11 MPa and 7 MPa, respectively, and the variation range of microhardness is reduced to 44 HV and 32 HV, respectively. The improvement of lubrication not only helps to reduce forming defects but also can obtain uniform mechanical properties. [ABSTRACT FROM AUTHOR]

Characterized by the advantages of high quality, flexibility, and productivity, laser welding of aluminum alloys is extensively applied in manufacturing fields such as automobile, aerospace, and railway. However, due to the low energy conversion efficiency and high carbon emission, the impact of laser welding on the environment cannot be ignored. Therefore, the environmental impact of the laser welding process should be quantified and a comprehensive evaluation considering both carbon emission and welding performance should be conducted. In this paper, the carbon emission characteristics of each subsystem (i.e., laser device, cooling device, motion device, and gas device) are analyzed, and a laser welding carbon emission model is established. In addition, deformation modeled via finite element method and tensile strength measured through orthogonal experiments are selected as welding performance evaluation indicators. Furthermore, the impacts of process parameters (i.e., welding speed, laser power, and defocus) on carbon emission, tensile strength, and deformation are implemented by Taguchi analysis. The results demonstrate that the welding speed is the dominant parameter affecting the carbon emission, followed by defocus, and lastly by the laser power. Moreover, the welding speed is also the dominant parameter impacting tensile strength and deformation. It is once again followed by defocus and laser power. Based on the TOPSIS (technique for order preference by similarity to ideal solution) method, the best-combined group is the 9th group with 75.8% relative closeness, while the worst is the 14th group with 7.9% relative closeness. The optimal combination is identified for the laser welding of 2670 W, welding speed of 9 mm/s, and defocus of −0.3 mm. The corresponding carbon emission, tensile strength, and deformation are 52.50 gCO2-eq, 181.78 MPa, and 1.21 mm, respectively. [ABSTRACT FROM AUTHOR]

The spread of 3D printing in many different fields has become eminent. This paper aims to improve the mechanical properties of parts printed by fused deposition modeling technique. Acrylonitrile butadiene styrene (ABS) specimens are printed with custom printing parameters. These parameters give a tensile strength that is 86% of the injection- molded ABS strength, and give one of the best recorded results for 100% infill printed ABS tensile specimens. Furthermore, a post filling technique has been studied. Specimens are printed with inner voids and different densities using slicing software. Void shape is precisely selected to conform to the filling process. High-strength, low-cost thermoset resin is injected through specimens to fill those voids. A tensile test has been performed after the full curing of the resin. A morphology analysis is done. Using this technique strength to printed weight ratio is improved by 151% and the cost is reduced by 51%. [ABSTRACT FROM AUTHOR]

Laser-based directed energy deposition (L-DED) is a rising field in the arena of metal additive manufacturing and has extensive applications in aerospace, medical, and rapid prototyping. The process parameters, such as laser power, scanning speed, and layer thickness, play an important role in controlling and affecting the properties of DED fabricated parts. Nevertheless, both experimental and simulation methods have shown constraints and limited ability to generate accurate and efficient computational predictions on the correlations between the process parameters and the final part quality. In this paper, two data-driven machine learning algorithms, Extreme Gradient Boosting (XGBoost) and Random Forest (RF), were applied to predict the tensile behaviors including yield strength, ultimate tensile strength, and elongation (%) of the stainless steel 316L parts by DED. The results suggest that both models successfully predicted the tensile properties of the fabricated parts. The performance of the proposed methods was evaluated and compared with the Ridge Regression by the root mean squared error (RMSE), relative error (RE), and coefficient of determination (R2). XGBoost outperformed both Ridge Regression and Random Forest in terms of prediction accuracy. [ABSTRACT FROM AUTHOR]

Due to their good mechanical and technological performances, thin substrate-supported metal layers are increasingly used as functional components in flexible electronic devices. Consequently, the prediction of necking, and the associated limit strains, for such components is of major academic and industrial importance. The current contribution aims to numerically investigate the respective and combined effects of strain rate sensitivity of the metal layer and the addition of an elastomer layer on localized necking in substrate-supported metal layers. To this end, strain rate-dependent forms for the flow theory of plasticity and the deformation theory counterpart are used to describe the mechanical behavior of the metal layer. As to the substrate layer, it is made of elastomer material whose mechanical response is described by a neo-Hookean hyperelastic model. The two layers are assumed to be perfectly adhered. Necking limit strains are predicted by the Marciniak-Kuczynski (M-K) imperfection approach. Various numerical results, corresponding to freestanding metal layers as well as substrate-supported metal layers, are presented and extensively discussed in this paper. The significant effect of strain rate sensitivity on the retardation of localized necking is first emphasized. Then, the combined and positive influence of strain rate sensitivity of the metal layer and characteristics of the elastomer layer (thickness and stiffness) on the enhancement of the ductility of the whole bilayer is analyzed and discussed. [ABSTRACT FROM AUTHOR]

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]

Ni–Ti alloys with multiple transformation temperatures for a single component can be called multi-functional Ni–Ti alloys. Multi-functional Ni–Ti alloys can increase the flexibility of designing complex systems and have broad application prospects. Existing research mainly focuses on manufacturing multi-functional Ni–Ti alloys through welding or changing the local Ni/Ti ratio. However, the above-mentioned methods have problems such as the low connection strength of the welded part, difficulty of precisely controlling the Ni–Ti ratio, and poor design flexibility. In this paper, laser powder bed fusion (LPBF) was used to successfully fabricate multi-functional Ni–Ti alloys. Ni-rich (Ni53.4-Ti46.6 (at.%)) powders and Ti–rich (Ni46.4-Ti53.6 (at.%)) powders were prepared. The Ni-rich powder was first used to fabricate super-elasticity (SE) parts with a high relative density. The Ti–rich powder was then used to manufacture shape memory effect (SME) parts with different process parameters based on the SE parts. These integrated components were processed into dog-bone shapes and subjected to tensile tests. The sample that had the highest ultimate tensile strength while manufactured at a relatively low energy density was selected for further analysis. The properties of the sample, such as the microstructure and transformation temperature, were analysed through a series of tests. The results confirm that LPBF is a suitable method to fabricate multi-functional Ni–Ti alloys. [ABSTRACT FROM AUTHOR]

A new nontraditional way of manufacturing crankshafts for medium speed diesel engines is proposed and evaluated by the state of the art of multibody dynamic analysis. Introduced for the first time in this paper, the new approach makes use of commercially unprecedented dual-metal cast-joining of nodular cast iron and forged steel. The strength of the dual-metal interface is validated by tensile tests with specially prepared dual-metal test coupons. The tensile tests revealed that the tensile strength of the dual-metal interface could be controlled to have over 700 MPa, which provides a fundamental basis to a dual-metal crankshaft. Given the reliable dual-metal cast joining, two dual-metal crankshafts, the so-called DM1 and DM2, are suggested and evaluated for two operational cases: an actual case of 100 bars of gas pressure; and a virtual case of 210 bars of gas pressure. The analysis results of the two cases demonstrated that one of the two dual-metal crankshafts, DM2, showed equivalent or outperforming fatigue performance over the traditional steel crankshaft. Therefore, by virtue of the new materialistic combination and the cast-joining technology introduced in this paper, the dual-metal crankshaft of nodular cast iron and forged steel presents a strong possibility to replace the traditional forged steel crankshaft, which is costly and low productive. [ABSTRACT FROM AUTHOR]

The hydro-assisted tube pressing (HATP) process is a new severe plastic deformation method that is proposed in this paper to improve the mechanical properties of long tubes. The pressured fluid between the tube and die eliminates the friction force between the tube and die and, thereby, decreases the required forming force. This facilitates the production of high-strength relatively long tubes. In the current study, this process was applied to a commercial pure copper tube during six passes at room temperature. Then, the hardness, tensile and electrical properties, and also microstructure of the samples were investigated. With increasing the number of passes, the grain size of the copper tube decreased. After two passes of the HATP process, the values of yield strength and ultimate tensile strength increased from 150 and 223 MPa to 347 and 366 MPa, respectively, and the total elongation decreased from 32 to 10%. After four passes, the tube hardness significantly increased from 81 to 132 HV, and a homogeneous distribution of hardness was obtained along with the tube thickness. The electrical conductivity of the copper tube decreased by 3% after two passes. Also, the effective plastic strain and the required processing force were investigated using the Abaqus commercial finite element software. It is concluded that the required force and the strain distribution are independent of the tube length. The hydro-assisted tube pressing method potentially can be used in the industrial production of long tubes with high mechanical strength and electrical conductivity. [ABSTRACT FROM AUTHOR]

Hybrid manufacturing approaches with additive and subtractive manufacturing is a promising technology for many sectors from personal care goods to aerospace. When it comes to the residual stresses, there are hardly about the additive manufacturing (AM). Although some researches have been conducted for the hybrid laser additive manufacturing and subtractive manufacturing (SM) processes, only the machining parameters, material properties, and surface quality were analyzed; there were a few experiments about the residual stresses. Taking this into account, this paper aims to analyze the surface residual stresses in hybrid manufacturing approaches. Additive machining process, electrochemical corrosion, and surface residual stresses testing were described in detail. The main results of the research would be references for the surface residual stresses when 316L stainless steel specimens are manufactured with laser metal deposition and milling after AM immediately. The oxidation is much serious in additive manufacturing, and the surface tensile stresses are quite small. Both the electrochemical corrosion and milling at high temperature will affect the distribution of the surface residual stresses. The residual tensile stresses are distributed symmetrically after milling process while they are asymmetric after electrochemical corrosion. [ABSTRACT FROM AUTHOR]

High-building multi-directional pipe joint is a complex structure. A novel technology, which is called wire and arc additive manufacture (WAAM), was used to manufacture a high-building 10-directional pipe joint in this paper. Because the intersecting areas of multi-directional pipe joint are space surfaces, the conventional planar slicing method of WAAM is hard to form space surface with high precision. According to the study of space surface slicing method and space path planning by WAAM, this paper used the outer cylinder surface of main pipe to slice other forming pipes of 10-directional pipe joint, and the intersecting surfaces could be divided into two kinds: smooth surface and curved surface with inflection point areas. Two different path filling schemes were proposed for different intersecting surfaces: The former was filled in rotating approaches, while the latter was filled in raster approaches. The dimensional errors of forming pipes were controlled about ± 1 mm, and the angle errors of intersecting pipes were less than ± 0.5°. Compared with the properties of the casting pipe joint, the tensile strength of 10-directional pipe joint increased by 12.4% and the impact toughness (20 °C) increased more than 100%. The microstructure mainly consisted of pearlite and ferrite, and average grain size was about 15 μm. Rare defects such as pores and cracks were found. [ABSTRACT FROM AUTHOR]

Laser shock tensioning process for circular saw blade was proposed in this paper. For exploring the stress formation mechanism of circular saw blade after laser shock tensioning process, theoretical model was built based on finite element method, some reasonable simplifications and assumptions. By comparing theoretical and measured results, the theoretical model was proved to be correct and laser shock tensioning process was proved to be feasible. The effects of spot diameter, impact zone radius, and number of circumferential impact zone on tensioning stress field were studied. Simulation results show that reducing spot diameter and extending impact zone are two effective ways for increasing the tangential tensile tensioning stress in the edge of circular saw blade and enhancing tensioning effect. An optimized scheme for laser shock tensioning process can be obtained by the theoretical model. [ABSTRACT FROM AUTHOR]

Spark plasma diffusion welding (SPDW) is a powerful technique for joining materials at a remarkably short time with excellent quality. In this paper, SPDW of 5A06Al alloy to itself was conducted with Al–20Cu–5Si–2Ni brazing filler alloy added as the interlayer. In the bonding temperature ranging from 520 to 550°C, pressure from 0.3 to 6 MPa, and holding time from 10 to 20 min, the optimal joint was obtained at bonding temperature of 540°C and pressure of 6 MPa for 10 min. Results showed that the void-free 5A06Al/5A06Al-bonded joint was obtained at the optimized parameters with the aiding of electric current and Al–20Cu–5Si–2Ni interlayer. Increasing the bonding pressure produced more refined grains in the bonding joint and was therefore beneficial to the bonding quality. The formation of refined eutectic phases, the accelerated atomic diffusion, the sufficiently removal of oxide film, and the evidently more narrowed bonding interface areas were helpful to strengthen the SPDW joint. The most efficient bonding joint had a tensile strength of as high as 220 MPa and exhibited typical fine ductile dimple fractography. Comparatively, the poorest joint quality was obtained at lower bonding temperature and pressure, i.e., bonding temperature of 530°C, pressure of 0.3 MPa, and holding time of 10 min. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies of the structure and properties of a wire with a diameter of 0.5 mm from an alloy of the Al-REM system with a rare-earth metal content of 7–9%. Wire obtained as a result of the implementation of the technology of its manufacture using the methods of casting into an electromagnetic mold (EMM), continuous extruding, and drawing. The rheological properties of the metal of continuously cast round billets from the experimental alloy obtained using an electromagnetic mold are determined. The modeling and analytical assessment of the possibility of carrying out the process of combined rolling-extruding (CRE) of such billets in a closed box-type roll groove of a continuous extruding unit are carried out. The features of metal shaping have been studied. The temperature-speed and technological parameters were found at which the CRE process can be carried out in a stable mode of operation. Data have been obtained for the forces acting on the die and rolls during rolling-extruding. The results of experimental studies of the process of obtaining longish deformed semi-finished products from an experimental alloy on the laboratory unit CRE-200 and the pilot plant unit CRE-400 are presented. The structure of the metal has been studied; data on the ultimate tensile strength, yield strength, relative elongation, and electrical resistance of hot-extruded rods and wires in cold-worked and annealed states have been obtained. It was found that the proposed processing modes make it possible to obtain by the method of combined rolling-extruding rods with a diameter of 9 mm in industrial conditions from longish billets with a diameter of 18 mm, cast by means of EMM. Wire in a cold-deformed and annealed state with a diameter of 0.5 obtained by drawing from the rods with a diameter of 9 mm from an experimental alloy of the Al-REM system containing 7–9% rare-earth metals with the required physical and mechanical properties. [ABSTRACT FROM AUTHOR]

Grain refinement by severe plastic deformation (SPD) techniques, as a mechanism to control microstructure (recrystallization, grain size changes,...) and mechanical properties (yield strength, ultimate tensile strength, strain, hardness variation...) of pure aluminium conductor wires, is a topic of great interest for both academic and industrial research activities. This paper presents an innovative finite element (FE) model able to describe the microstructural evolution and the continuous dynamic recrystallization (CDRX) that occur during equal channel angular drawing (ECAD) of commercial 1370 pure aluminium (99.7% Al). A user subroutine has been developed based on the continuum mechanical model and the Hall-Petch (H-P) equations to predict grain size variation and hardness change. The model is validated by comparison with the experimental results and a predictive analysis is conducted varying the channel die angles. The study provides an accurate prediction of both the thermo-mechanical and the microstructural phenomena that occur during the process characterized by large plastic deformation. [ABSTRACT FROM AUTHOR]

The most advanced metal 3D printing promises to revolutionize the manufacturing industry and has already played their strengths in the field of part repair and surface coating, but they have not yet reached the best operability in the overall manufacturing. The challenge is how to design the process route. Therefore, the entire process of blade design-manufacture-testing was carried out in this paper. The fifth-degree polynomial is used to construct the blade, and on this basis, a CAD model of a thin-walled blade with torsion was established. After the blade was manufactured by LMD, the geometric dimensions and mechanical properties were tested. The test results show that the standard deviation of the blade body part is less than 0.3 mm, which basically meets the design requirements. The Vickers hardness of LDM blades changes continuously along the deposition direction, mainly due to the changes in the structure caused by different cooling rates. The tensile strength of the blade is basically the same in the 0°, 45°, and 90° directions, which is greater than 770 MPa. The elongation in different directions differs more than 5% and has obvious anisotropy, which is mainly caused by the organization structure and the way of unit cell stacking. [ABSTRACT FROM AUTHOR]

The mechanical properties of a fused deposition modeling (FDM) process product are greatly influenced by many process parameters. The identified parameters namely deposition orientation, layer thickness and deposition style, raster width, and raster gap are more significant factors contributing to the strength of a FDM product. In this paper, tensile strength, flexural strength, and impact strength are considered as three evaluation indexes to characterize the mechanical properties of a FDM part. An experimental research approach based on the Taguchi method was presented and some special specimens were designed. The influences of the five parameters on the three evaluation indexes were analyzed by the use of analysis of variance (ANOVA). Finally, based on the gray relational analysis, a set of optimal process parameter combination was obtained to optimize comprehensive mechanical properties of FDM parts. [ABSTRACT FROM AUTHOR]

The current paper investigates the mechanical behavior of Al-6063 hybrid composites reinforced with silicon carbide (SiC) and rare earth (RE) oxides. Hybrid composites containing wt% of SiC as 3, 6 and 9% and (CeO2 + La2O3) mixture as RE oxides as 1,2 and 3 wt% were fabricated using stir casting technique. The scanning electron microscopy (SEM), X-Ray diffraction (XRD), electron backscattered diffraction (EBSD) and energy dispersive spectroscopy (EDS) analysis were used to characterize the prepared samples of hybrid composites. The mechanical characterization including Rockwell hardness, Vicker's microhardness, impact strength and tensile strength were tested as per ASM standards. The fractured samples of different hybrid composites were studied using SEM. The highest value of Rockwell hardness was observed as 69 HRB in composite sample with 6 wt% of SiC and 2 wt% of RE mixture. For the same sample, highest value of Vicker's microhardness was found to be 114.24 HV. Furthermore, highest value of tensile strength and impact strength was observed to be 91 MPa and 56 J for the same sample. The obtained data were analyzed on Design Expert software Version 6.0.8 using two level factorial designs afterward. The regression equations obtained from the software is validated using diagnosis plots and the optimized values of reinforcements are obtained using desirability analysis. [ABSTRACT FROM AUTHOR]

The continuous drive friction welding of aluminum alloy to stainless steel was investigated in this paper. Microstructural characterization, intermetallic compound (IMC), and mechanical properties of the friction welded Al/Fe joint were studied. Results showed that thermal mechanically affected zone (TMAZ) at the Al side was subjected to both thermal cycling and mechanical force, and grain size was 1–3 μm, and streamlines were more dramatically than at the steel side. In fully dynamic recrystallized 127 zone (FDRZ), microstructure became the fine equiaxed grains, and its width at the steel side was about 5 μm. The local Si enrichment IMC layer was formed at the interface area of Al/Fe joint, and its average thickness was about 300 nm. IMC layer was relatively flat at the steel side, while uneven at the Al side. The hardness reached to the maximum value (395.8 HV) at the steel side in FDRZ, and the average hardness was only 76 HV in heat-affected zone (HAZ) at the Al side. When forge pressure was below 220 MPa, the tensile strength of joint was approximately linearly related to the forge pressure. [ABSTRACT FROM AUTHOR]

Wood-plastic composites (WPC), made of wood fiber (WF) and thermoplastics, have been well developed and commercialized in construction, packaging, automotive, and furniture industry over the past three decades, as they are environmentally friendly and require less maintenance compared with natural wood. Polypropylene (PP) is one of major thermoplastics used in WPC. However, the relatively poor mechanical properties of WPC prevent them from penetrating into other structural applications where strong mechanical properties are required. To enhance the mechanical properties of PP/WF composites, this paper applies one-step direct injection molding to produce the hybrid WPC with glass fiber (GF) and carbon fiber (CF). Compared with those of PP/WF composites, the tensile strength and tensile modulus of PP/WF/GF hybrid composites increased 30% and 26%, respectively, and the tensile strength and tensile modulus of PP/WF/CF hybrid composites increased 38% and 78%, respectively. Apart from the significant increase of mechanical properties, the additional benefit of hybrid WPC was that their flame-retarding property was improved. Particularly, the dripping behavior (or fire spreading) during burning associated with WPC was significantly reduced or eliminated for the hybrid composites. In addition, the water absorption and the surface roughness of hybrid composites were also studied. This study demonstrates that it is feasible to make hybrid WPC with one-step injection molding, and hybrid WPC open the door to their potential structural applications. [ABSTRACT FROM AUTHOR]

Submerged friction stir welding on magnesium (Mg) alloy is investigated with limits in the past. ME20M is an important lightweight Mg alloy with enhanced yield strength and heat resistance that merits further research. In this paper, submerged friction stir welding of ME20M Mg alloy was carried out in different temperatures of cooling water. Three-dimensional numerical was employed to analyze the thermal field under the same weld conditions, and the numerical predictions were compared with the experimental results. The macrostructure, microstructure, tensile properties, and hardness are tested. The results show that the numerical results and the experimental results exhibits the same trends. By increasing the cooling water temperature, the grain size of the weld nugget increased, the tensile strength of the joint decreased, and the microhardness of the weld joint decreased. The largest tensile strength was 170.5 MPa, which was ~ 71.04% of the base metal. The highest and the lowest hardness values of the weld joint were obtained at the cooling water temperature of 15 °C and 75 °C, respectively, in the weld nugget and heat-affected zones. [ABSTRACT FROM AUTHOR]

The primary purpose of this research is investigating the effect of increasing temperature on mechanical properties and formability of Al 5083 produced by equal channel angular rolling (ECAR) process. The present work also aims to study the feasibility of increasing temperature as an approach for solving the ductility problem of ultrafine-grained Al 5083, although some strength of the material might be sacrificed. So, the quantitative and qualitative analysis of the effect of temperature increase on mechanical properties and formability has been done. In this paper, the ECAR process has been performed at three different temperatures (i.e., 25 °C, 200 °C, and 300 °C(. Then, the investigation of mechanical properties such as yield strength, ultimate tensile strength, and microhardness after each pass of the ECAR at different temperatures has been performed. The results showed that by applying the ECAR process at a specified temperature, the mechanical and microhardness properties of the samples improved, while elongation to fracture reduced. At ambient temperature, and after the 3rd pass of the ECAR process, yield strength, ultimate tensile strength, and microhardness compared with the annealed sample increased by 94%, 19%, and 52%, respectively. Also, the mechanical properties of samples after the ECAR process in a specified pass at different temperatures have been evaluated. The obtained results showed that by increasing temperature, the yield strength, ultimate tensile strength, and microhardness of the samples decreased, but the elongation to fracture as well as the forming limit diagram (FLD) improved. The results illustrated that by applying the ECAR process at a specified temperature, the level of the FLDs moved downward. Also, the FLDs after the 3rd pass of the ECAR at different temperature have been compared. The results showed that the FLD0 (the major forming limit strain in-plane strain mode) at a temperature of 200 °C and 300 °C compared with the ambient temperature increased by 5% and 20%, respectively. [ABSTRACT FROM AUTHOR]

Bobbin tool friction stir welding (BTFSW) is a relatively new, solid-state welding technology, but its control is not the same as the conventional friction stir welding (FSW) due to the unique welding tool structure. In this paper, closed-loop control system was developed and the Smith predictive proportional-integral-derivative (PID) control method was presented to assist the welding system in producing an appropriate interface temperature response. As it is difficult to accurately detect the temperature in full range of the welding zone, the tool-workpiece interface temperature is detected by thermocouple and wireless transmission technology. Initial experiments were conducted to derive a qualitative understanding of bobbin tool friction stir welding processes. Ziegler-Nichols setting method was adopted to determine parameters of the PID controller. While examining the capabilities of Smith predictive PID control in BTFSW, this paper focuses on the control effect of hysteretic characteristics of welding temperature during butt welding. A compensation strategy was setting gaps along the welding path, and the gap could affect the distribution of temperature. Through our experiments, we demonstrate that temperature control strategy is feasible, and the tensile properties of the weld are uniform along the welding direction. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study of the tensile performance, heat treatment, fracture, decrease of residual stress, second-phase particle and microstructures of a 316L stainless steel fabricated by directed laser deposition (DLD) and thermal milling (starting milling temperature at 250 ± 50 °C), a typical hybrid additive and subtractive manufacturing process. Experiments of different post-heat treatment temperatures and tensile tests at room temperature were performed. The residual stress was eliminated with heat treatment at 400 °C for 2 h, and the average residual stress decreased 53.7% while the yield strength and ultimate strength decreased slightly. The fracture surfaces of different heat treatment temperatures were observed. The typical ductile fracture microstructures of dimples were seen in almost all specimens whenever the heat treatment temperature was low or high. The evolution of dimples from formation to destruction by heat treatment was analyzed. The different morphology and composition of the second-phase particles of different heat treatment temperatures were compared. The yield strength of 427.5 MPa, the ultimate strength of 599.27 MPa, and the elongation of 36.48% showed the new hybrid manufacturing technology could be used for further fabrication of components. [ABSTRACT FROM AUTHOR]

In order to obtain easily good joint with no crack at the interface between Ni-based superalloy (Ni-SA) and heat-resistant steel (HRS), the investigation of weldability in those material combinations by friction welding method is required. This paper described the joining phenomena and the tensile strength of the friction-welded joint between Ni-SA and HRS. The joining phenomena during the friction process, such as joining behaviour and friction torque, were measured. The effects of friction pressure, friction time, and forge pressure on the joint tensile strength were also investigated, and the characteristics of joints were observed and analysed. The good joint, which had the fracture in the HRS base metal and the tensile strength of its base metal with no crack at the weld interface, could be successfully achieved, although it had the hardened and softened areas at the adjacent region of the weld interface. In conclusion, it was found that the joint should be made with an opportune friction time after the HRS side was transferred to the entire weld interface on the Ni-SA side and with adding high forge pressure such as 360 MPa. Hence, the good joint could be obtained by friction welding method. [ABSTRACT FROM AUTHOR]

This paper reports on the time dependency of mechanical properties and component behavior during the first hours after friction stir welding (FSW). Three different aluminum alloys, two age-hardened alloys AA 6014-T4 and 6016-T4 and as a reference 5182-O/H111, are welded and samples are taken from the steady-state region immediately. Those samples are examined at various time intervals by means of tensile and hardness testing to quantify local properties and their recovery over time. Initially, the FSW process leads to a significant reduction in mechanical properties of the age-hardened alloys and to an altered, time-dependent component behavior as opposed to the base material. For AA 6014 and 6016, all mechanical properties recover significantly within a few hours after welding, whereby the gradient is initially very steep and levels out after 1–2 days. Gradients of up to 6 MPa/h and relative increases of more than 25% are observed for ultimate tensile strength within the first 2 days. As such, the increase in strength within the heat-affected zone and with it the entire welded component can be compared to natural aging after solution annealing. The results show the importance of considering the time dependency for weld qualification and also for comparing studies of age-hardenable alloys. [ABSTRACT FROM AUTHOR]