Average Ultimate Tensile Strength Research Articles

Improved material properties of wire arc additively manufactured Al-Zn-mg-cu alloy through severe deformation interlayer friction stir processing and post-deposition heat treatment

In this study, Al-Zn-Mg-Cu alloys were prepared by wire arc additive manufacturing (WAAM) combined with interlayer friction stir processing (IFSP). To enhance the FSP region, an improved stirring pin was designed to broaden the stir zone effectively. Moreover, the effects of typical T6 and T73 heat treatments on the microstructure and mechanical properties of as-deposited (AS) specimen were meticulously investigated. The results indicated that heat treatments had minimal impact on grain size, dislocation density, and texture strength, but significantly altered the type, size, and distribution of precipitates. The differences in strength were primarily attributed to precipitation strengthening rather than grain boundary or dislocation strengthening. Following T6 heat treatment, the precipitates were predominantly η’, which were smaller in size and exhibited a significantly increased number density compared to AS specimen. Therefore, the average yield strength (YS) and ultimate tensile strength (UTS) increased by 39.51 % (500.21 MPa) and 15.84 % (584.26 MPa), respectively. In contrast, T73 treatment caused a substantial number of fine η’ to transform into coarser η, leading to a significant decrease in precipitate number density. Consequently, compared to T6 specimen, the average YS and UTS decreased by 47.19 % and 13.13 %, respectively.

Relationship between grain structure evolution and tensile anisotropy in Al-Zn-Mg-Cu cylindrical part formed by additive friction stir deposition

The thick-walled Al-Zn-Mg-Cu cylindrical part was obtained by additive friction stir deposition, and the relationship between grain structure evolution and tensile anisotropy was investigated in detail. The intra-layer grains are significantly refined due to continuous dynamic recrystallization (CDRX), and the grains at the interface are further refined by 30%-45% due to geometric dynamic recrystallization (GDRX). The early cracking and ductility deterioration under Z direction loading are caused by strain localization due to coarse and fine grain distribution and pre-existing strain at the interface. The grain growth rates for specific orientations (Cube, P, Q, and Rotated Goss) are higher than average, and the mismatch in elastic modulus between these grown grains and the matrix results in ductility differences in the X and Y directions. Texture components and residual stresses affect yield strength in the X and Y directions. Meanwhile, dissolution of η/η' and the coarsening of the particles due to the thermal cycling effect leads to a decrease in the yield strength in the building direction. The average ultimate tensile strength (UTS) and elongation (El) of the part could reach 370 MPa and 20%, respectively. The tensile properties of the as-deposited Al-Zn-Mg-Cu cylindrical part are generally higher than those of melt-based additive manufacturing, but lower than those of the extruded and forged states due to the dissolution and coarsening of the strengthening precipitates during thermal cycling.

3D printing of high-stiffness and high-strength glass fiber reinforced PEEK composites by selective laser sintering

Glass fiber reinforced poly-ether-ether-ketone (PEEK) composites are emerging as structural materials of multifunctional devices in space applications, due to their outstanding mechanical properties, electrical insulating properties, and resistance to irradiation. Here, a new approach for preparing glass fiber/PEEK powders tailored for selective laser sintering (SLS) process is proposed. The surface of glass fiber is modified with the sulfonated PEEK following the designed procedure. The flowability of glass fiber/PEEK powders is also improved by adding the nano-scale SiO2 flow agent. The glass fiber reinforced PEEK composites are successfully 3D printed using the glass fiber/PEEK powders. Further, the enhancement of interfacial bonding between PEEK and glass fiber is analyzed through quasi-static tension tests and scanning electron microscopy (SEM) for the SLSed glass fiber reinforced PEEK composites. The average ultimate tensile strength reaches approximately 100 MPa using these optimal process parameters, while the average elastic modulus is around 7 GPa. Finally, the upper limit of fiber weight fraction is evaluated with the X-ray computed tomography (XCT) and the high-fidelity discrete element method (DEM) simulation.

Local and global mechanical properties of orbital friction stir welding on API X65 PSL2 steel / Inconel 625 clad pipes

Orbital friction stir welding (FSW) is a promising approach to joining clad pipes. In this work, the influence of individual process parameters on the material flow even as, mechanical properties in orbital friction stir welded clad pipes is investigated. Due to the local heterogeneous microstructures within the weld, joints were evaluated by optical and scanning electron microscopy (SEM), microhardness, and digital image correlation (DIC). A microhardness increase was observed, with a maximum of 380 HV0.5 within the Inconel 625 and 265 HV0.5 within the X65 steel stir zones. Sound joints had an average ultimate tensile strength (UTS) exceeding up to 13% of the calculated theoretical tensile strength, which is obtained considering the minimum tensile strength of both materials. Additionally, failure occurred in the base material during the tensile testing, where the local strain in the stir zones of the X65 steel and Inconel 625 were only 3.3% and 10%, respectively. In summary, this investigation shows friction stir welded joints of API X65 steel and Inconel 625 clad pipes with high mechanical properties.

Enhancing microstructural integrity and mechanical performance of thick wire-arc directed energy deposited eutectic aluminum-silicon solid structure through continuous multi-pass friction stir processing

In wire-arc directed energy deposition (waDED), fabricating larger 3D components with single-layer tracks is challenging due to limitations in track thickness, requiring the development of bead overlapping strategies. However, fusion-based 3D-printed aluminum structures often show porosity and coarse-grained microstructures, limiting their industrial applications. To address these limitations, this study employs continuous multi-pass friction stir processing (FSP) on a waDED-produced aluminum block (140 mm × 150 mm × 28 mm). The severe plastic deformation induced by FSP triggers dynamic recrystallization (DRX), promoting the formation of equiaxed grains with an average grain size 8.75 times smaller than the as-fabricated waDED sample (67.03 μm vs 7.66 μm). Transmission Electron Microscopy (TEM) revealed decreased dislocation loops post-FSP, indicating DRX and dislocation annihilation. X-ray micro-computed tomography (X-CT) examination showed complete elimination of porosity in the waDED sample, owing to the intense mechanical stirring induced during FSP. Scanning electron microscopy (SEM) images of the waDED samples showed fibrous eutectic networks disrupted by FSP, leading to a uniform distribution of broken Si particles within the α-Al matrix. Hardness decreased by approximately 38 % (86 HV0.1 vs 53 HV0.1), while the average ultimate tensile strength decreased by about 4 % in the FSP-treated samples (159.19 MPa vs 153.02 MPa). Additionally, the formation of alpha fiber and weak cube texture components during FSP enhances ductility, as evidenced by a sixfold improvement in elongation (1.93 % vs 11.59 %). This textural transformation contributes to the characteristic deeper and more uniform dimples in the FSP-treated samples, indicative of ductile fracture, compared to the premature failure patterns in as-deposited samples.

Microstructure and mechanical properties of GH4169 thin-walled parts fabricated by ultrasonic vibration assisted laser directed energy deposition/milling hybrid process

Ultrasonic vibration (UV) was employed for the first time to assist laser directed energy deposition/milling hybrid process (LMHP) in fabricating GH4169 thin-walled parts. The effects of building strategy, including UV-assistance, milling rounds, and building heights, on the thermal history, printability, microstructure, and mechanical properties of the fabricated thin-walled parts were systematically investigated. The thermal history analysis revealed that the UV-assistance resulted in a reduction in the average temperature of the laser scanning area, an increase in pore defects, and compromised surface finish due to an enlarged molten pool and enhanced heat transfer. Moreover, the thin-walled parts exhibited refined grain structure, equiaxed crystallization, homogenized element distribution, decreased proportion of the Laves phase, and increased strength with UV-assistance. Notably, the grain size was significantly reduced from a millimetre scale to 86.2 μm, while the average yield strength increased from 489.1 MPa to 523.6 MPa and the average ultimate tensile strength increased from 747.1 MPa to 830.4 MPa. Furthermore, introducing more hybrid-processed interfaces within a certain distance allowed for further grain refinement, enhanced strength, and decreased elongation in the GH4169 thin-walled part. This work is anticipated to provide a comprehensive understanding of the thin-walled parts fabricated by UV-assisted LMHP with high surface quality and superior mechanical properties.

The Effect of Interpass Temperature on the Mechanical Properties and Microstructure of Components Made by the WAAM Method from Inconel 718 Alloy

The following study examines the impact of temperature on the deposition of components using Cold Metal Transfer–Wire Arc Additive Manufacturing technology. In the experiment, two overlay weld wall structures were created by applying an interpass temperature of 100 °C and without additional cooling. Subsequently, the microstructural and mechanical properties were observed. No changes in the microstructure due to the application of the interpass temperature were confirmed, and the microstructure of the manufactured components, in both cases, consisted of columnar dendrites. It was found that applying an interpass temperature reduced the average ultimate tensile strength by nearly 65 MPa and the average offset yield strength by 82 MPa. The influence of the cooling strategy on the resulting microstructure was not confirmed. Transmission electron microscopy analysis confirmed the presence of strengthening phases γ′/γ″ in both components; however, a larger amount of the strengthening phase γ″ was found in the component manufactured without the application of an interpass temperature.

Ultrasonic Influence on Macrostructure and Mechanical Properties of Friction Stir Welded Joints of Al/Mg Sheets with 2 mm Thickness.

Friction stir welding (FSW) and ultrasonic vibration enhanced FSW (UVeFSW) experiments were conducted by using 6061-T6 Al alloy and AZ31B-H24 Mg alloy sheets of thickness 2 mm. The suitable process parameters windows were obtained for the butt joining of Al/Mg sheets. The effect of ultrasonic vibration on the macrostructure and mechanical properties of the dissimilar joints was studied. The results showed that the width of the weld nugget zone (WNZ) was enlarged to some extent and the hardness distribution in WNZ was more uniform in UVeFSW. In addition, the application of ultrasonic vibration effectively promoted the interpenetration degree of dissimilar materials in the WNZ so that the mechanical interlocking on the bonding interface of dissimilar Al/Mg materials was enhanced. The facture positions were changed from the bonding interface in FSW to the boundary between WNZ and the thermo-mechanical affected zone, and the ductile fracture zone was expanded. The highest ultimate tensile strength was 205 MPa at the process parameters set of 1200 rpm-50 mm/min in UVeFSW in this experiment. The average ultimate tensile strength of FSW/UVeFSW joints was 172.3 MPa and 184.4 MPa, respectively, and the average ultimate tensile strength was increased by 7.02% with the introduction of ultrasonic vibration.

Functional behaviour of novel multi-layered deposition via twin wire arc additive manufacturing: Microstructure evolution and wear tailoring characteristics

Twin wire arc additive manufacturing offers advantages such as high deposition rates and the ability to use a wide variety of materials, making it suitable for large-scale metal part production with enhanced efficiency and flexibility. Functionally graded deposition (FGD) based structure of dissimilar steels (SS316LSi and ER70S-6) fabricated via twin wire arc additive manufacturing and their detailed performance analysis are accomplished in the current research work. Microstructural, mechanical, and tribological characteristics of the deposited structure were investigated and analysed. Microstructure reveals polygonal ferrite, widmanstatten ferrite, skeletal ferrite, lathy ferrite, ferrite solidification, and ferrite to austenite (F/A) transformation. FGD structure possessed a microhardness of 371 HV. Average ultimate tensile strength, yield strength, and elongation percentage were 675.98 MPa, 414.21 MPa, and 38.37 %, respectively. In wear analysis, the average coefficient of friction value of WAAM-processed FGD samples is 0.44–0.49. 3D profilometer analysis reveals that average values of roughness, maximum height of roughness, and maximum roughness valley depth are significant with increasing applied loads. The findings of the present research focus on the quality and appropriateness of dissimilar steels for structural applications and provide a novel method for creating high-strength components.

Experimental investigation on solidification cracking & intergranular corrosion of AISI 321 & AISI 316 L dissimilar weld on pulsed current gas tungsten arc welding (PCGTAW)

Dissimilar metal combinations are frequently employed in the power generation and nuclear industries. Where stainless steel piping systems are connected to pressure vessels made of low-alloy steel, the subsystems of liquid rocket engines also have different, dissimilar material combinations. Dissimilar welding plays a vital role in ensuring the integrity, performance, and reliability of components and structures operating in cryogenic environments, in this study, plates of AISI 316L and AISI 321, each 5 mm thick, were successfully joined using the pulsed current gas tungsten arc welding (PCGTAW) technique with optimized process parameters. These weld joints are mostly present in rocket engines subjected to a cryogenic environment. Due to the low temperature environment, the metallurgical properties of these joints change, which affects their mechanical properties. As it is a structural part, PCGTAW welding is most common method for joining this kind of material.In this work, Microstructural analysis of the weldment revealed a combination of vermicular, lacy, and acicular ferrite morphologies in the fusion zone at the root, mid, and crown locations.Furthermore, no solidification cracking was detected in the weldments based on the optical micrograph and SEM results. Intergranular corrosion (IGC) testing indicated the absence of a ditch structure, suggesting that the heat-affected zone (HAZ) on both sides of the weld joint was not being susceptible to sensitization. However, the HAZ of the AISI 316L side exhibited coarser grains compared to AISI 321. Analysis of tensile properties revealed a significant influence of the testing environment on the tensile strength of the dissimilar welded joints. At room temperature, the average ultimate tensile strength (UTS) was measured as 621 MPa. Remarkably, at cryogenic conditions, the average tensile properties significantly increased to 1319 MPa.Microhardness analysis showed the highest hardness associated with the AISI 321 side. The fusion zone exhibited a large deviation in the hardness profile (205 ± 10 HV), with the highest average hardness observed in the middle part of the weld. However, the hot cracking behavior of the weld was investigated by using a suutula diagram at various locations of the weld. The investigation revealed that the Creq/Nieq ratio exceeded the critical threshold value, effectively diminishing the propensity for hot cracking in the fusion zone. Overall, these findings underscore the effectiveness of the PCGTAW technique in joining dissimilar materials, as well as the importance of microstructural and mechanical property evaluations, especially under extreme operating conditions such as cryogenic temperatures.Paraphrase.

Microstructures and mechanical behaviour of bimetallic structures of tungsten alloy (90WNiFe) and nickel alloy (In625) fabricated by wire-arc directed energy deposition

ABSTRACT This study reported the fabrication of bimetallic structures (BS) from tungsten alloy (90WNiFe) and nickel alloy (In625) via wire-arc directed energy deposition (DED)-based additive manufacturing (AM). Its microstructures and mechanical properties were investigated for three different heat input conditions: low (180A), medium (200A), and high (220A). The highest average ultimate tensile strength of 618 MPa was achieved in the low heat input condition, with an average elongation of 49%. Although the ultimate tensile strength of the produced BS is lower than that of 90WNiFe and In625 individually, its yield strength closely resembles that of In625 processed by wire-arc DED. Tensile samples from each heat input condition experienced different fracture locations and exhibited distinct fracture morphologies. It can be concluded that the bonding strength is attributed to the diffusion of chromium, nickel, molybdenum, and niobium from In625 into the γ-(Ni, Fe, W) binding matrix of the 90WNiFe substrate.

Microstructure and properties of metal inert gas welded joints in a novel Al–Mg–Zn–Er–Zr alloy

Metal inert gas (MIG) welding of a novel Al-5.82Mg-0.61Zn-0.14Er-0.11Zr alloy was performed using ER5E61 and ER5B71 filler wires. The effect of the two filler wires on microstructures and mechanical properties of MIG welded joints was investigated. The study shows that fully penetrated joints are obtained by MIG welding process filled with ER5E61 and ER5B71 wires. Compared with ER5B71, the weld metal (WM) with ER5E61 exhibits a coarse structure and high solid solution of Mg and Mn elements. After the tensile test, the WM with ER5E61 and ER5B71 wires is composed of elongated coarse grains with a higher proportion of low angle grain boundaries (LAGBs). In addition, the lattice rotation occurring within the grains, indicating that single grain has an unevenly plastic deformation after the tensile test. The average microhardness of the WM is 83.4 HV and 82.9 HV for ER5E61 and ER5B71 wire, which is the lowest microhardness in the MIG welded joint. The average ultimate tensile strength (UTS) and elongation index (EI) of the MIG joints are 327.7 MPa and 8.5% for ER5E61 wire, and 314.3 MPa and 8.2% for ER5B71 wire, suggesting the MIG welded joint with ER5E61 wire achieves a good combination of strength and ductility. Quantitative assessments of the effects of different strengthening mechanisms on the strength reveal that dislocation strengthening and solid solute strengthening are the main factors to obtain a higher strength of welded joints with ER5E61.

Mengoptimalkan Analisis Sifat Mekanik Material Berbasis Data Dengan Pandas Profiling

The analysis of mechanical properties based on data is a method used to analyze the mechanical properties of a material using data, typically obtained from a material database. This process encounters several challenges, such as large volume of data, complexity in data processing, as well as difficulties in data visualization and interpretation. In this study, Pandas Profiling, a Python library designed specifically for automated dataset analysis, was employed. The dataset used consisted of tensile test results for various austenitic stainless steel types such as SUS 304, SUS 316, SUS 321, SUS 347, and NCF 800H. This dataset comprised 1916 samples with attributes related to mechanical properties and factors influencing them. The analysis results using Pandas Profiling indicated a strong negative correlation between heat treatment temperature and Yield Strength (YS) and Ultimate Tensile Strength (UTS). Additionally, a positive correlation was found between chemical elements such as Copper (Cu) and Nickel (Ni) with Elongation (EL). Furthermore, the analysis results revealed that stainless steel treated with water cooling exhibited a higher average UTS value, measuring at 493 MPa, compared to air cooling, which only reached 403 MPa. Pandas Profiling offers an effective solution to overcome common challenges in data-based mechanical property analysis, including dealing with large data volumes, complex data processing, as well as challenges in data visualization and interpretation. By utilizing Pandas Profiling, researchers can easily comprehend the dataset comprehensively, identify patterns, trends, and relationships among variables, and optimize the analysis process of data-based material mechanical properties.

Effect of heat treatment on the microstructural evolution and mechanical property of nickel-based superalloy K447A manufactured by Powder Bed Fusion Laser Beam (PBF-LB)

Nickel-based superalloy is an indispensable material in the aerospace industry. With the development of metal additive manufacturing theory, the additive manufacturing technology will further expand and accelerate the application of nickel-based superalloy in the aerospace industry. In this study, nickel-base superalloy K447A with high volume fraction γ′ strengthening phase was formed by Powder Bed Fusion Laser Beam (PBF-LB), and the effect of different heat treatments on the microstructure and mechanical properties of K447A alloy was analyzed. In the as-built sample, cellular structures consisting of dense dislocation tangles were formed. Elongated columnar grains grew preferentially along <001> direction. Fine MC precipitates segregated at the boundary of cellular structure. The process of grains recovery (1185 °C), grains recrystallization (1260 °C), and grains rapid growth (1300 °C) of K447A alloy during heat treatment could be observed. Many stable and homogeneous cubic γ′ phases precipitated from the K447A alloy after high-temperature heat treatment. When the heat treatment was increased to 1300 °C, MC precipitates dissolved and the number of carbides in the ST-1300 sample was significantly reduced. The average microhardness and ultimate tensile strength of the as-built sample were 407 HV and 527 MPa, respectively. When the heat temperature reached 1260 °C, the microhardness and ultimate tensile strength reached the maximum. When the heat temperature was raised to 1300 °C, the ultimate tensile strength decreased sharply, but the elongation and the toughness increased significantly. Based on the above results, the relationship between microstructure, mechanical properties, and deformation mechanism was discussed.

Effects of heat treatments on the microstructure and mechanical properties of Inconel 718 alloy fabricated by electron beam freeform fabrication

The present study investigated the effects of different heat treatments on the microstructure and mechanical properties of Inconel 718 alloy fabricated by electron beam freeform fabrication. The Laves phases, γʹ phases, and (Nb,Ti)C particles were precipitated in the as-deposited specimen. Solution at 960 °C promoted the partial dissolution of Laves phases and the precipitation of δ phases. Further increasing the solution temperature to 1060 °C dissolved the Laves phases effectively, facilitating the adequate precipitation and uniform distribution of γʹ and γʹʹ phases during the subsequent double aging heat treatment. The ultimate tensile strength (UTS) and elongation of the as-deposited specimen were 770 MPa and 12.2 % respectively. The solution heat treatment at 1060 °C increased the elongation to 38.1 % but decreased the UTS to 734 MPa. The microhardness and UTS of specimens that underwent double aging heat treatment were significantly increased, with the maximum average microhardness and UTS reaching 491 HV0.5 and 1285 MPa, respectively. The undissolved Laves phases and the precipitated δ phases at grain boundaries impaired the ductility. The transformation from single solution or double aging heat treatment to solution plus double aging heat treatment led to a shift from a ductile fracture mode to a mixed ductile and brittle fracture mode.

Increasing strength properties in sinter-based additive manufacturing of SS316L via metal material jetting of sub-micron powders

Metal Binder Jetting (MBJ) 3D printing is an attractive additive manufacturing (AM) method for high volume production of metals and ceramics. However, the widespread use of MBJ has been stymied by longstanding challenges in reduced strength properties compared with traditional wrought and laser-based AM materials. In this study, we leveraged novel “drop-on-demand” Metal Material Jetting (MMJ) of sub-micron powders to fabricate SS316L samples. These samples were subjected to dilatometry, mechanical testing, and correlative materials characterization and compared to metal binder jet (MBJ) SS316L to evaluate differences in process-structure-property relationships between the two processes. Overall, MMJ SS316L possessed an average tensile yield and ultimate tensile strength of 312 ± 84 MPa and 640 ± 38 MPa respectively, greatly exceeding MBJ SS316L in the literature due to the formation of fine microstructures with an average grain size of 2.4μm. Importantly this led to significant Hall-Petch strengthening but also considerably lower average failure strains (15.5 ± 4.8 %). The process-microstructure-property relationships facilitating microstructural evolution in MMJ are discussed and further elucidated using an isotropic pressure-less viscous sintering model. Results of this model show that, although densification behaviors in MMJ were largely similar to those in MBJ, MMJ samples possessed over three-fold increase in sintering stress, defined the change in free surface energy with respect to the volumetric shrinkage, and ∼31 % reduction in grain growth due to the employment of sub-micron size powders. Overall, these results show the promise of MMJ AM for structural metals and suggest that both microstructure (and ultimately strength) of MMJ materials can be further tuned by controlling the overall sintering process.

Structure refinement and performance balance of high-strength aluminum alloys using an improved thermomechanical treatment process

The microstructure of 7A85 aluminum alloy forgings often contains coarse second-phase particles and grains. To improve the microstructures and balance the properties, we used an enhanced thermomechanical treatment process that included multiaxial hot forging, multiaxial cryoforging (MACF), and three-step aging treatment. We thoroughly investigated the effects of MACF with 1–3 passes on the evolution of microstructure, three-dimensional (3D) mechanical properties at the center and edge, fracture toughness, and corrosion resistance of the alloy. Our findings revealed that multiaxial hot forging had a limited ability to crush the coarse second-phase particles. However, the higher flow stress and compound brittleness of MACF resulted in a significant increase in particle fragmentation and driving force for precipitation. Additionally, under MACF, massive dislocations proliferated due to the inhibition of dynamic recovery, forming large orientation gradient regions, which promote static recrystallization and grain refinement during solution treatment. As the number of MACF passes increased from one to three, the effect of particle crushing initially increased and then plateaued, the 3D grain sizes first decreased and then slightly increased, and the spacing of grain boundary precipitates (GBPs) increased. The dense and uniform precipitates, finest equiaxed grains, a low fraction of coarse particles, and large GBP spacing in MACF2 resulted in the higher strength, highest elongation with minimal anisotropy, superior fracture toughness, and enhanced corrosion resistance. Ultimately, MACF2 demonstrated the best overall performance and good homogeneity, with an average 3D ultimate tensile strength, average 3D yield strength, average 3D elongation, and fracture toughness at the center of 548 MPa, 476 MPa, 13.4%, and 42.5 MPa m1/2, respectively. These values were respectively 4.2%, 1.9%, 50.6%, and 13.9% higher than those of the uncompressed sample.

Microstructure and mechanical properties of wire-arc directed energy deposited Al-Mg-Sc aluminum alloy: As-deposited and aging heat treated

In this study, Al-Mg-Sc aluminum alloys were fabricated using wire-arc directed energy deposition. The focus of the study was to analyze the microstructure and mechanical properties of these alloys. Comparative analysis was conducted on the samples obtained from the as-deposited and aging treated, respectively. Furthermore, the precipitation process of the second phases and the associated strengthening mechanism were elucidated. The findings revealed that the presence of precipitated Al3(Sc,Zr) particles acted as heterogeneous nucleation nuclei of α-Al, facilitating the formation of equiaxial grains. During the subsequent aging treatment, the secondary Al3(Sc,Zr) particles precipitated directly without transitioning through intermediate phases. Additionally, the experimental results demonstrated that these secondary Al3(Sc,Zr) phases hindered the dislocation movement, leading to enhanced mechanical properties in Al-Mg-Sc alloys through precipitation strengthening. In the horizontal direction, the average ultimate tensile strength (UTS) and yield strength (YS) were measured as 361 ± 5 MPa, 251 ± 4 MPa, and 281 ± 6 MPa, 179 ± 6 MPa in the vertical direction, respectively. The elongations were found to be 15.8 ± 0.8% and 4.0 ± 0.5% in the horizontal and vertical directions, respectively. The observed variations in mechanical properties were attributed to the presence of interlayer pores.

Effect of SS-316L and nickel-based interface powders on joint characteristics of microwave welded SS-316L plates

Microwave energy has been exploited as a rapid and volumetric heating source in various manufacturing applications, such as microwave joining. This study used stainless steel (SS-316L) plates to be microwave-joined at 2.45 GHz. The microwave hybrid heating (MHH) technique was used to prepare joints inside a microwave applicator using nickel-based (EWAC 1004EN) and SS-316L interfacing powders at 900 W. Microstructural and mechanical characterizations of the developed joints were performed to understand the effect of the interface powder on weld quality. Microstructural observations revealed adequate metallurgical bonding between interfacing powders and bulk metal with columnar and dendritic grains (EWAC-based joint) and equiaxed grains (SS-316L-based joint). The phase analysis revealed the presence of intermetallic phases such as iron-nickel, chromium carbide, and chromium iron carbide in EWAC-based joint and iron-nickel, nickel-chromium, and chromium carbide in SS-316L-based joint, which contribute to enhanced joint microhardness compared to base alloys. A larger grain size, more low-angle boundaries, and higher misorientation angles were found in the EWAC-based joint. Furthermore, the average ultimate tensile strength of SS-316L-based joints was 26% higher, with a 6.9% enhanced elongation, than that of EWAC-based joints. The EWAC-based joint exhibited better corrosion resistance than that of SS-316L-based joint.

Effects of multi-axial compression and double-step aging on the microstructure and mechanical properties of Al alloy 7075

This study investigates the combined effect of severe plastic deformation via multi-axial compression (MAC) and subsequent double-step aging on the microstructure and mechanical properties of annealed 7075 Al alloy. Three distinct processes were employed: (1) double-step aging on the annealed sample, (2) double-step aging on the six-MAC pass processed sample, and (3) double-step aging without solutionization on the six-MAC pass sample. Process (2) yielded the most significant improvements in mechanical properties. Compared to the annealed sample, the six-MAC pass, double-step aged sample exhibited an average ultimate tensile strength increase of 134% and an average Vickers micro-hardness (HV) increase of 209%. This superior performance is likely attributable to the synergistic effect of grain refinement induced by MAC and precipitate hardening achieved through double-step aging. A comprehensive analysis of microstructure evolution, mechanical properties, fractography, and the relationship between them was conducted for all three processes. This in-depth examination provided valuable insights into the mechanisms governing the observed property enhancements, particularly in process (2). Additionally, a variety of characterization techniques were employed to comprehensively evaluate the material's mechanical and microstructural characteristics.