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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]

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]

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]

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]

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]

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]

The present paper aims to study different laser drilling/cutting parameters including laser intensity, cutting speed, and gas pressure in order to achieve minimum surface roughness (Ra), heat-affected zone (HAZ), taper angle (TA), and maximum tensile strength (TS) of the laser-drilled glass fiber-reinforced plastic (GFRP) laminate. Full factorial design of experiment method and analysis of variance were adopted to investigate the effect of each parameter on the responses, and in addition, the surface roughness and tensile strength were compared with that of conventional drilling. The morphology of the laser-drilled holes was studied through the scanning electron microscopy (SEM). It was found that optimum laser drilling parameters can yield higher tensile strength and lower surface roughness in drilled GFRP laminate compared to the conventional drilling. Moreover, multi-response optimization was carried out on the results in order to obtain maximum tensile strength, minimum HAZ, minimum surface roughness, and minimum taper angle. The results revealed that the laser intensity, cutting speed, and assist gas pressure should be set at 2.04 W/cm2, 8 mm/s, and 4 bar, respectively, to obtain higher tensile strength and surface integrity. The results drawn from this study can be applied to improve the surface quality and mechanical properties of laser drilling of FRP materials especially in aircraft part manufacturing. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) has various independent parameters that affect the mechanical properties and quality of the produced parts that are not linearly the function of each other. Process parameters in metal AM are very hard to control, analyse and optimise because they affect each other even though they can be independently changed. Changing process parameters in a wide range is not possible due to the formation of problems such as cracks, balling, unmelted powders, porosity and distortion. In this paper, a numerical model to predict the value of tensile strength of selective laser melting (SLM) Ti-6Al-4V parts and analyse the effect of process parameters on the results has been proposed. Taguchi L25 Design of Experiment (DOE) across 125 samples to create a comprehensive and general overview of influential parameters on the build process was investigated. Specifically, parameters included laser power, scan speed, hatch spacing, laser pattern angle and heat treatment (HT). To evaluate and analyse the build process according to established statistical variances, a minimum of five samples based on ASTM standard (for tensile test) were prepared. Heat treatment was added to the DOE to analyse the combined process and post-process effects. Results were compared (cross-validated) against existing values found in the literature and were found to effectively predict and explain the behaviour of tensile strength when changing process parameters. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the effect of printing parameters and their interactions on the mechanical properties of ABS-based specimen, 3D printed by fused deposition modeling (FDM), using the response surface method. The manufacturing direction (X, Y, or Z) and the deposition angle (0°, 30°, or 45°) are analyzed as input factors. The Young modulus, the yield stress, the tensile strength, and the deformation at fracture in tension are considered as responses. An empirical model for each response is built in terms of factors and their interactions. The predicted results are in good coherence with experimental ones. The original contribution of this paper consists in the evaluation of the optimal combination of manufacturing parameters thanks to the MINITAB software. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) started as a rapid prototyping (RP) technology to aid in visualizing and validating designs in the design process. However, with the recent improvements in metal AM parts, functional parts can be manufactured using laser-based AM. Currently, metal AM parts have comparable mechanical properties to traditional manufacturing parts. 15-5PH stainless steel and Inconel 718 are two of the most commonly used metals in laser-based AM, and they have a high modulus of elasticity and tensile strength and can be precipitate hardened to increase their strength and hardness by heat treatment. These properties make 15-5PH stainless steel and Inconel 718 suitable for many industrial applications such as aerospace and automotive. However, due to the nature of AM, AM parts usually suffer from anisotropy. In this paper, the mechanical properties such as tensile strength, modulus of elasticity, yield strength, and ductility are investigated at various elevated temperatures up to 350 °C and compared with the mechanical properties at room temperature using specimens printed in three different orientations to capture the effect on the anisotropy. In addition to that, the microstructure of the specimens is studied to investigate the influence of elevated temperature on the specimens. [ABSTRACT FROM AUTHOR]

Incremental sheet forming (ISF) is a promising method for forming metal sheets, by which parts can be manufactured without the use of dedicated dies. However, the process has not been widely used for industrial application due to the unsatisfactory service performance of the formed parts. This paper focuses on improving the thickness distribution and mechanical properties (e.g., hardness, yield strength, and tensile strength) through process optimization. The response surface methodology with a Box-Behnken design is used to investigate how different process parameters affect the thickness thinning and mechanical properties. A set of experiments with 15 tests for pyramid-forming process is performed, and three parameters including step-down size, sheet thickness, and tool diameter are considered. The results show that the maximum thinning rate is lower with larger step-down size and larger tools. In addition, compared with the initial sheet, the values of hardness, yield strength, and tensile strength have been increased considerably due to the strain hardening. The present work provides useful guidance in improving the product quality formed by incremental sheet forming. [ABSTRACT FROM AUTHOR]

In this paper, the effect of additive particles on the mechanical properties of ultraviolet (UV)-cured resin was evaluated based on tensile strength and shear strength. The experimental results showed that the tensile strength was improved with proper particle addition, but the shear strength was always decreased. Moreover, the effects of additive particles on the holding force of diamond abrasive, critical exposure energy, and penetration depth of UV-cured resin were elucidated. The holding force of resin with 15 wt.% Al2O3 addition was found to be higher than that of pure UV resin. Based on the experimentally determined critical UV exposure energy and penetration depth, UV-cured resins with and without additive particles were used to fabricate grinding wheels using additive manufacturing technology. Grinding experiment demonstrated the performance of UV resinoid grinding wheels was significantly improved with the addition of 15 wt.% Al2O3 particles. [ABSTRACT FROM AUTHOR]

The forming temperature of cross-wedge rolling (CWR) usually ranges from 950 to 1150 °C, but reducing the forming temperature has some advantages. This paper presents a comprehensive study of warm and hot cross-wedge rolling by using high-strength bolts as a case. Numerical simulation and experimental trials were conducted to make a detailed comparison of warm and hot cross-wedge rolling. Forming quality, microstructure, and mechanical properties of the rolled rods were investigated using scanning electron microscopy (SEM) and tensile testing. The results show that the rolling force and torque of warm cross-wedge rolling (WCWR) are more than three times greater than those of hot cross-wedge rolling (HCWR), and the workpiece rolled by WCWR shows more pit and stacking defects but fewer central cavities. The dispersing spheroidized cementite on ferrite matrix generated in WCWR results in decreased hardness and tensile strength of the rolled rods and a significant increase of elongation, which improves subsequent machinability. [ABSTRACT FROM AUTHOR]

This paper deals with the direct recycling of EN AW 2011 aluminum alloy turning chips into semiproducts utilizing forward hot extrusion process. The main goal of this study is to obtain mathematical models that will relate the process parameters of direct recycling to mechanical properties of final semiproducts. Influence of chip size, compaction force, and extrusion temperature on mechanical properties was investigated using Box-Behnken experimental design. The study has shown that the most influential factor on mechanical properties was extrusion temperature. Chip size does not affect both ultimate tensile strength and yield strength and on the other hand, compaction force does not influence on both ultimate tensile strength and percent elongation. Optical microscopy revealed cracks and inhomogeneities for all samples extruded on 300 °C in contrast to those extruded on 500 °C which showed no voids or cracks. Optimal recycling process parameters that would give maximal mechanical properties were found. [ABSTRACT FROM AUTHOR]

Weld line problem which occurs in polymer parts produced by plastic injection method and affects appearance and strength on a large scale was researched in this paper. The three parameters affecting operation were called injection pressure, injection time, and packing pressure which influence the quality of weld line on the polymer products were researched. A joint which enables two different parts used in different places to be joined together and its subjection to a certain loan were discussed. Considering the usage area of the part, composite of glass fiber reinforced polyamide (PA 6 GFR 30) was chosen as the material, and the design process of the part was implemented. Samples were prepared by altering the determined injection parameters. Weld line of the produced samples were subjected to tensile strength test. Their structure parts were examined under the SEM, and the results were gathered. [ABSTRACT FROM AUTHOR]

This paper studied the combined effects of matrix-to-reinforcement particle size ratio (PSR) and SiC volume fraction on the mechanical properties of extruded Al-SiC composites. A powder metallurgy technique (PM) of cold pressing at 500 MPa followed by hot extrusion at 580 °C was adopted to produce Al/SiC composite. Aluminum powder of size 60 μm and silicon carbide with different sizes, i.e., 50, 20, and 8 μm, were used. Three different volume fractions of SiC were employed, i.e., 5, 10, and 15 %, for each investigated size using a constant extrusion ratio of 14.36. The effect of matrix-to-reinforcement PSR on the reinforcement spatial distribution, fabricability, and resulting mechanical properties of a PM-processed Al/SiC composite were investigated. It has been shown that small ratio between matrix to reinforcement particle size resulted in more uniform distribution of the SiC particles in the matrix. As the PSR increases, the agglomerations and voids increase and the reinforcement particulates seem to have nonuniform distribution. In addition, the agglomerations increased as the volume fraction of the SiC increased. It has also been shown that homogenous distribution of the SiC particles resulted in higher yield strength, ultimate tensile strength, and elongation. Yield strength and ultimate tensile strength of the composite reinforced by PSR (1.2) are higher than those of composite reinforced by PSR (7.5), while the elongation shows opposite trend with yield strength and ultimate tensile strength. [ABSTRACT FROM AUTHOR]