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Welding titanium to copper is challenging due to the differences in their thermophysical properties and the formation of intermetallic compounds (IMCs). This study uses gas tungsten arc welding to join commercially pure titanium sheets to electrolytic tough pitch copper without using filler metal, and electrical currents ranging from 80 to 100 A to achieve completely penetrated joints. Microstructure analysis shows the formation of a columnar structure of IMCs at the weld zone, including Ti2Cu, TiCu, Ti3Cu4, Ti2Cu3, and TiCu3. Tensile and three-point bending tests were carried out to investigate the effects of IMCs formed by welding on the mechanical properties. The maximum tensile strength was achieved for the sample with the thinnest intermetallic layer, while brittle fractures were observed in all samples. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) alloys are used more frequently as a replacement for heavier structural materials because of their advantageous specific strength and eco-friendly attributes. Their fusion welding is a difficult process, but the friction stir welding (FSW) offers a potential solution to these issues. In this study, a thermal analysis is carried out to obtain the temperature distribution and residual stresses related to FSW of different Mg-Al-Zn series Mg alloys under different processing conditions. The highest temperature recorded at the centre of the weld was 544.04°C, while the average von Mises stress during welding was 185.07 MPa. These values were achieved with a tool rotational speed of 1000 rpm, welding speed of 40 mm/min, and a tool shoulder diameter of 21 mm. The temperatures obtained through the numerical model were validated by comparing them with experimental data. During the experimental analysis, small cracks were observed at the centre of the welded joint, resulting from the formation of MgO. The welded joint exhibited a maximum tensile strength of 234.86 MPa, which is approximately 90% of the stronger AZ31 Mg alloy. [ABSTRACT FROM AUTHOR]

This study investigates how fusion zone (FZ) chemical composition influences the formation of the halo ring, a transient softening region that can form along the fusion boundary (FB) of resistance spot welds in Q&P980. For this purpose, spot welds were made in both similar Q&P steel joints as well as joints sandwiching low carbon (LC) or high carbon (HC) steels with Q&P steels, which tailored the chemical composition of the FZ. Electron probe microanalysis (EPMA) was performed on a spot-welded sample to understand the effect of material chemical composition on the halo formation. Alloying elements such as C, Mn, and Si were significantly less in the FZ composition of the welds made with LC steel, as compared to 3-sheet Q&P weld, which resulted in associated 33 pct reduction in hardness of the LC steel FZ. On the contrary, the C and Mn were higher in the FZ of the weld made with HC steel compared to that of the 3-sheet Q&P weld. However, like the welds made with the LC steel the FZ of the welds with the HC steel had a lower Si content than the FZ of the 3-sheet Q&P steel. The increase in C and Mn contents in the welds made with the HC steel resulted in an 14 pct increase in FZ hardness compared to the FZ of the 3-sheet Q&P steel. The halo formation is more prominent in welds made with LC steel. It was wider in welds where the FZ had a lower alloy content than the Q&P steel as compared to the higher alloyed FZ of the weld made with the HC steel. In LC steel weld a high Mn and Si segregated region inside the FZ was also observed. It was shown that the transient softened zone can be affected by the difference in chemical composition between the FZ and heat-affected zone (HAZ). Therefore, any changes in mechanical properties associated with the halo are more likely to be more prominent in dissimilar welds where high and low alloy steels are combined. [ABSTRACT FROM AUTHOR]

The document "Welding, Joining, and Additive Manufacturing: Experiments, Materials, and Modeling" published in the journal "Materials (1996-1944)" discusses the challenges and advancements in welding, joining, and additive manufacturing technologies. It covers various experiments, mathematical modeling, and characterization techniques for materials ranging from simplistic to exotic. The research presented in this special issue focuses on fusion welding, wire arc additive manufacturing, and other critical aspects of these processes, providing valuable insights for the manufacturing industry. The document highlights the importance of understanding the physical behavior of welding and additive manufacturing processes through experiments, mathematical modeling, and characterization techniques. [Extracted from the article]

Friction-stir-welded dissimilar AA2024/AA7075 joints have an apparent influence on grain and texture development at the weld interface due to differences in physical and chemical properties between the two aluminum alloys. In this work, the effect of tool shoulder profile on grain structure and texture evolution in the center interface zone (CIZ) and bottom interface zone (BIZ) of dissimilar AA2024/AA7075 joints were quantitatively studied by electron back-scattering diffraction (EBSD). The results indicate that abundant fine and coarse equiaxial grains are produced in the CIZ and BIZ of the joints produced with a concentric circle shoulder (CCS) and three-helix shoulder (THS), and the average grain size of the BIZ is lower than that of the CIZ for the same CCS or THS joint. A higher degree of recrystallization occurs in the CIZ of the joint with a CCS than that of the joint with a THS, while a similar degree of recrystallization is presented in the BIZ of the two joints. For the distribution of local misorientation angle between the two sides of the interface in the same CCS or THS joint, the CIZ manifests relatively uniform behavior, while the BIZ presents the characteristics of uneven distribution. Tool shoulder profile has a significant impact on the texture components at the weld interface, which results in different types of shear textures generated in the CIZ and BIZ of the two joints. It is beneficial to make out the microstructural evolution mechanism at the weld interface in dissimilar FSW joints for engineering applications in this study. [ABSTRACT FROM AUTHOR]

This study investigated the effects of laser energy density at different scanning speeds on the microstructure evolution, phase equilibrium, mechanical properties, and fracture modes of welds in dissimilar steel welded joints (Q345D and 20Mn2). The connection of dissimilar steel welded joints is achieved by using a laser synchronous powder feeding method. The microstructure and phase evolution of the joint were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Mechanical property testing was performed on the joint via a micro-Vickers hardness tester and an electronic testing machine, and the fracture surface morphology was observed via a scanning electron microscope. The results show that when the laser energy density is 1125 J/mm2, the fine cellular crystals, columnar crystals, and equiaxed crystal structures of the joint are more uniformly distributed. As the laser energy density increased, the transition of the Q345D side structure from cellular to columnar crystals and the transition of the 20Mn2 side structure from cellular to equiaxed crystals became more pronounced. Mechanical property testing revealed that an increase in the laser energy density can significantly improve the microhardness and tensile strength of a joint. However, a large amount of the Fe matrix from the 20Mn2 side permeates into the coating, making the mechanical properties of the dilution zone lower than those of the crystallization zone, and making it more prone to fracture on this side. The fracture analysis results show that the fracture mode has strong ductility, and the fracture mode is judged to be ductile fracture. [ABSTRACT FROM AUTHOR]

The current study aims to explore the impact of friction stir welding (FSW) parameters on the tensile strength of dissimilar joint materials. A copper grade CDA 101 and an AISI-SAE low-carbon steel grade 1010 were selected as the dissimilar materials to analyze the tensile strength of the weld joints. The axial force, tool rotational speed, and welding speed were selected as process parameters for the weld joint fabrication process. The influence of the process constraints was investigated using the Taguchi technique, which is based on the L9 orthogonal array. Investigation of variance and signal-to-noise ratio were considered to forecast the ideal welding process constraints, and their percentage of contribution was computed by comparing the anticipated and actual welding process parameters. The test results revealed that the speed of the tool and the downward force (axial) exerted on the joint played a substantial impact on the joint strength. The maximum tensile strength of the Cu-steel dissimilar weld joints is found as 189 MPa which is determined during optimal welding process parameter values having tool rotating speed of 1100 rpm, welding speed of 40 mm/min, and an axial force of 6 kN. The FSW joints were inspected under a scanning electron microscope (SEM) and with an EDAX to identify the micro patterns and fracture surface of the joints. [ABSTRACT FROM AUTHOR]

Rotary friction welding is a solid-state welding process that can manufacture high-integrity joints between similar and dissimilar materials with short weld times. However, access to expensive and complex industrial-grade friction welding machines is not always possible. This study explores the design process and functionality of a laboratory-scale friction welding setup following the fundamentals of large-scale machinery. The proposed setup is designed to be easily manufactured, employing the use of a calibrated drill press and load cell, thus ensuring welding parameters such as rotational speed and applied axial load are monitored. The decision to investigate rotary friction welding of aluminium bronze Ca104 to austenitic stainless steel AISI316 was taken to explore the limitations of this bespoke friction welding machine for prospective applications in the nuclear energy sector. The workpieces were friction welded at four sets of rotational speeds with constant friction and forging pressures. The microstructural evolution and mechanical properties of the dissimilar material welds were investigated via optical and scanning electron microscopy with energy dispersive spectroscopy, 4-point bend testing and microhardness measurements. Results show a change in the hardness along the weld interface and evidence of metallic diffusion between the dissimilar materials, demonstrating the successful application of the small-scale experimental setup. [ABSTRACT FROM AUTHOR]

The present study explores the creep and high-temperature tensile performance of the P92/304L dissimilar weld joint. The gas tungsten arc welding (GTAW) technique was used to prepare the dissimilar weld joint between P92 creep strength enhanced ferritic (CSEF) steel and 304L austenitic stainless steel (SS) by utilizing ERNiCrMo-3 filler metal. After welding, tensile strength was evaluated at 450, 550, 650, 750, and 850 °C temperature to examine the performance of the dissimilar weld joint at elevated temperatures. The high-temperature tensile test result indicated that the ultimate tensile strength (UTS) decreased from 439 to 58 MPa, and yield strength (YS) fell from 155 to 41 MPa during the test from 450 to 850 °C. After high-temperature tensile strength, the creep performance of the P92/304L dissimilar weld joint has also been investigated at 650 °C in the stress range of 100-200 MPa. All the creep specimens failed from the P92 steel parent metal region during the creep test at different conditions. The maximum creep life of 706.9 h was observed for the specimen tested at 650 °C under 100 MPa. The minimum creep life of 11.9 h was observed for the specimen tested at 650 °C under 200 MPa. The relationship between the rupture time and applied stress followed the logarithmic equation as log (tr) = log (14.39695) + (− 5.79039) log (σ). The softening of the parent metal matrix due to the consumption of the solid solution strengthening W and Cr elements and the coarsening of the precipitates were the main reasons behind the creep failure at 650 °C in the stress range of 100-130 MPa. The plastic deformation caused by the grain boundary sliding was mainly responsible for creep failure at 650 °C in the stress range of 150-200 MPa. [ABSTRACT FROM AUTHOR]

This study explored the heat input effects on automated TIG welded dissimilar AA6061-T6 and AA7075-T6 joints using filler ER5356. Three heat input welded samples, namely HI1 (0.73 kJ/mm), HI2 (1.69 kJ/mm), and HI3 (2.27 kJ/mm), were utilized and their corresponding microstructure and grain boundary features were investigated and correlated with the joint's mechanical properties. Electron backscattered diffraction (EBSD) results showed that the low-angle grain boundaries (LAGBs) in the base alloys transformed into high-angle grain boundaries (HAGBs) in the fusion zone (FZ) after welding. However, the grain boundary transformations were more pronounced in the high heat input welded sample HI3. Pole figures revealed strong dominance of A 1 ∗ / A 2 ∗ and A/ A - textures with a small amount of C and B/ B - textures at the FZ for all the heat input joints. Orientation distribution functions also exhibited the recrystallization textures P {011} <112> and Goss {110} <001> , plane strain texture S {123} <634> with some deformation texture H {001} <110> at the FZ center. The medium heat input sample HI2 had the highest tensile strength of 182 MPa, elongation of 14.4%, and flexural strength of 202 MPa; while, the welded sample HI1 had the highest microhardness of 81 HV when compared to other welded samples. The HI2 joint fracture surface exhibits fine dimples devoid of porosities, suggesting ductile fracture manner. However, the fracture surface of the HI3 joint displayed both smooth and rough cleavage facets with coarser dimples, resulting in a combination of ductile and brittle fracture modes. [ABSTRACT FROM AUTHOR]

Dissimilar steel welded structures are commonly used in the marine engineering field. Owing to the scarcity of in-depth investigation into the intricate pattern of residual stress distribution in welding within 316L/Q345 dissimilar steel welded joints and methods for reducing this stress, a platform-based vibratory stress relief (VSR) experimental system was established to comprehensively study the effects of VSR on the mechanical properties and microstructure of 316L/Q345 welded structures. Scanning electron microscopy (SEM) was used to examine the fracture morphology and explore the intrinsic mechanisms by which VSR enhances the mechanical properties of welded joints. The findings suggest that VSR is capable of significantly homogenizing and diminishing the welding residual stress within the heat-affected area of 316L/Q345 mismatched steel welded specimens. The significant reduction in residual stress after VSR can primarily be attributed to the combination of alternating stress applied by the VSR platform and the welding residual stress, which exceeded the yield limit of the metal materials. Furthermore, the significant reduction in residual stress, refinement of second-phase particles, and changes in fracture mechanisms are the main reasons for the increased strength observed after VSR. This study has significant engineering application value, providing a theoretical basis for the use of VSR treatment to enhance the reliability of the safe operation of marine engineering equipment. [ABSTRACT FROM AUTHOR]

As a main component of the magnetic pulse welding (MPW) system, the working coil exerts a great influence on the electromagnetic force and its distribution, which, in turn, affects the quality of the MPW joints. This study proposes a structural parameter optimization of the MPW coil, with the objective of achieving a higher induced current density on the flyer plate. The optimal Latin hypercube sampling technique (OLHS), Kriging approximate model, and the Non-Linear Programming by Quadratic Lagrangian (NLPQL) algorithm were employed in the optimization procedure, based on the finite element model built in LS-DYNA. The results of the sensitivity analysis indicated that all the selected parameters of the coil had a specific influence on the induced current density in the flyer plate. The optimized coil structure serves to refine the pulse current flowing path within the coil, effectively reducing the current loss within the coil. Additionally, the structure reduces the adverse effect of the current within the coil on the induced current within the flyer plate. Numerical results show the peak-induced current of the flyer plate increasing by 25.72% and the maximum Lorentz force rising by 58.10% at 25 kJ with the optimized coil structure. The experimental results show that with the same 25 kJ discharge energy, the optimized coil could increase the collision velocity from 359.92 m/s to 458.93 m/s. Moreover, 30 kJ of discharge energy should be needed to achieve the failure mode of base material failure with the original coil, while only 15 kJ should be applied to the optimized coil. These findings verify the optimization model and give some outline for coil design. [ABSTRACT FROM AUTHOR]

The document discusses laser welding technology, highlighting its benefits such as fast welding speed and high productivity. It delves into various aspects of laser welding, including the joining of different materials, monitoring and control of the welding process, and research on advanced control methods. The Special Issue covers a wide range of topics related to laser welding, showcasing contributions from different research groups on improving welding quality and efficiency through the analysis of different process parameters and methods. The document emphasizes the importance of laser welding in industrial manufacturing and its applications in joining metals and polymers. [Extracted from the article]

The dissimilar welding of aluminium (Al) alloy to mild steel (MS) carries significant importance in automotive applications to reduce the weight of components and cost without compromising on the strength. The computer numerically controlled (CNC) welding machines offer the flexibility and desired accuracy to develop the welds compared to conventional manually operated welding machines. The fusion-based joining of dissimilar aluminium alloy and mild steel is challenging owing to the metallurgical incompatibility and differences in physical and mechanical properties. Hence, in the presented work, a CNC friction stir spot welding (CNC-FSSW) machine was used to make the Al/MS spot welds for automotive applications. The CNC-FSSW parameters were optimized using Taguchi based desirability function approach (DFA) to obtain greater tensile shear fracture load (TSFL) bearing property of spot joints. The Minitab software was used to design the L9 orthogonal array experimental design matrix. The Al/MS joints when fabricated using the DFA optimized FSSW parameters involving tool rotational speed—TRS of 1200 rpm, tool plunging rate—TPR of 14 mm/min, dwell time—DT of 5 s and tool diameter ration—TDR of 2 exhibited the higher TSFL and WNH of 3.78 kN and 144 HV respectively. The joints made using DFA optimized FSSW parameters showed 18.12% and 20% improvement in TSFL and WNH of Al/MS joints. The most significant FSSW parameter influencing the composite desirability was observed to be TRS (rpm) followed by TPR (mm/min), TDR and DT (s). [ABSTRACT FROM AUTHOR]

There has been a consistent increase in the utilization of laser sources, resulting in a decrease in expenses and an increase in efficiency. Several factors have contributed to this phenomenon, including advancements in procedures and machinery such as laser beam welding systems. Inconel 718 is a highly utilized material in the manufacturing of chemical, nuclear, and marine equipment. Conversely, SS304 is commonly used in the food processing, automotive, and aerospace industries. It is crucial to conduct a thorough investigation of the welding techniques employed for dissimilar metals, with particular emphasis on SS304 and Inconel 718. The current investigation employed the Taguchi design methodology. The amalgamations of LP at 2.7 kW, WS at 2.35 mm/min and PD at 6.5 ms accomplishes minimalized top and bottom width. Likewise, an amalgamation with 3.1 kW LP, 2.05 mm/min WS and 7.5 ms PD accomplishes maximized feasible penetration which consequences in quality joints. The research has revealed that the laser power is the primary process variable that significantly impacts the width of both the upper and lower sections. The velocity at which welding is performed is a crucial factor that influences the rate of penetration. The attainment of optimal penetration can be facilitated by the combination of elevated levels of peak power and pulse duration with reduced levels of weld speed. [ABSTRACT FROM AUTHOR]

The objective of present research work is to study joint strength and corrosion behaviour of dissimilar Friction Stir Welding (FSW) of Al 7075 and Mg AZ31 alloys with Cd and Zn interlayer. The FSW process performed at rotational speed 1300 rev min–1 and travel speed 20 mm min−1. The comparative study of mechanical properties and corrosion behaviour of FSW with Cd and Zn interlayers has been attempted for the first time. The result shows that the maximum tensile strength of 129 MPa has been achieved for FSW with Cd interlayer as compared to 85 MPa in the case of FSW with Zn interlayer. The corrosion rate was found in order of FSW with Cd > FSWwith Zn > BM AZ31 > BM-7075. It has been concluded that FSW with Zn interlayer resulted in comparatively lower strength and better polarisation resistance than the FSW with Cd interlayer in 3.5 wt-% sodium chloride (NaCl) solution. [ABSTRACT FROM AUTHOR]

Copyright of Metal Working (1674-165X) is the property of Metal Working Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Metal Working (1674-165X) is the property of Metal Working Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article outlines the development and examination of the properties of an asymmetrical dissimilar metal joint produced using friction welding (FW). Friction welding involving dissimilar materials, specifically a 50 mm (length) × 45 mm (width) × 20-mm (thickness) electrolytic tough pitch copper (ETP-Cu) plate and a 12.5-mm-diameter SS304L rod, was carried out. The assessment of the asymmetrically welded components encompassed ultrasonic testing, high-pressure helium gas testing, leak testing, tensile testing, scanning electron microscopy, optical microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, hardness measurements, and elemental mapping via X-ray. Significantly, there was an observed increase in tensile strength, resulting in a joint efficiency of 86.50% compared to the ETP-Cu base material, following FW between an asymmetric ETP-Cu plate and SS304L rod. The study unveiled notable variations in the microstructure near the joint interface on the ETP-Cu material side. Intermetallic compounds, such as FeCu4 and Cu9Si phases, were detected within the reaction layer at the interface between ETP-Cu and SS304L, exhibiting a variable thickness ranging from 30 to 50 μm. [ABSTRACT FROM AUTHOR]

This study aims to optimize the tungsten inert gas (TIG) welding parameters for joining AISI 316L stainless steel and Cu-ETP copper using 309L stainless steel filler rods. Welding dissimilar materials is challenging due to their significant differences in thermal and mechanical properties. The high thermal conductivity of Cu-ETP copper leads to rapid heat dissipation, causing uneven heat distribution at the weld interface. To address this issue, the research team applied a 1 mm offset of the welding torch toward the copper side to balance the heat input. They employed statistical analyses using ANOVA and the Taguchi method to determine the optimal process parameters. The results showed that the optimal welding current, welding speed, and gas flow for achieving high tensile strength (Rm) are 90 A, 0.5 mm/s, and 12 l/min, respectively. Among these, welding speed emerged as the most significant factor, influencing 48.74% of the weld characteristics. Mechanical testing confirmed that these parameters produced high-quality welds. Metallurgical analysis revealed minimal diffusion between the materials, preserving their distinct properties while minimizing the formation of undesirable intermetallic phases. These results highlight the effectiveness of TIG welding in creating robust joints between AISI 316L stainless steel and Cu-ETP copper for applications requiring a combination of both materials' properties. [ABSTRACT FROM AUTHOR]

The current study delves into the dissimilar laser welding of nickel-base alloy and duplex stainless steel, specifically in circular and plate forms, using fiber laser technology. The study utilizes a design of experiments methodology, specifically employing a central composite design, to methodically evaluate how different laser welding parameters affect the properties of dissimilar welds. The methodology is the response surface methodology (RSM), allowing for a comprehensive evaluation of the effects. The study examines the influence of key welding parameters, such as laser power, welding speed, focal distance, and laser beam deviation from the joint's center, on several response variables. These variables encompass the depth of the molten pool, the weld microstructure, and its mechanical characteristics. The depth of the molten pool, on the other hand, is primarily influenced by laser power and focal distance. Notably, a transition in microstructure is observed from columnar dendrites to a cellular configuration as one moves from the fusion line towards the center of the fusion zone. In the fusion zone of the duplex base metal, an unmixed zone is identifiable in the upper segments of the fusion line. This phenomenon arises due to incomplete melting at the fusion line. [ABSTRACT FROM AUTHOR]

The dissimilar 05Cr17Ni4Cu4Nb stainless steel and HR-2 stainless steel were welded without groove and wire filling by laser deep fusion welding. The microstructure characteristics, mechanical properties, and Crep on the corrosion resistance of the joints with different laser power were investigated in detail. The weld metals (WM) of the dissimilar joints illustrated ferritic-austenitic mode of solidification with different welding processes. The joints with lower laser powers present fine grain and excellent mechanical properties. The tensile specimens failed at the HR-2 side and massive dimples were distributed in the fracture surface, indicating typical ductile fracture mode of the joints. The EDS results of the WM show that the white granular carbides are mainly NbC and M23C6 (M denotes Cr and Fe elements) precipitated phases. The results of electrochemical test show that the best corrosion resistance of the joints is achieved with higher Crep in the WM. [ABSTRACT FROM AUTHOR]

This study explores the dissimilar welding of nickel superalloy 59 with Fe-Ni superalloy 904 L using the Gas Tungsten Arc Welding with Hot Wire technique (HW-GTAW). The HW-GTAW process produced defect-free weldments with complete penetration, as confirmed by macroscopic analysis. Microstructural analysis using FESEM and EDS revealed fine equiaxed and columnar dendrites in the fusion zone and identified a secondary phase enriched with chromium. XRD analysis supported the presence of predominant austenitic phases and indicated the formation of Cr23C6-type carbide. The grain size of the weld joint, determined using the Gaussian method and Scherer formula, was 44.53 nm, slightly smaller than base metals. Microhardness tests revealed values ranging from 226 ± 5 HV 10 to 243 ± 5 HV 10, with the highest values observed in the deep cryogenic treatment (DCT). The Mo in the ERNiCrMo-13 filler and the effects of DCT, which promote grain refinement, are responsible for this increase in hardness. Residual stress measurements revealed a maximum tensile stress of 315 MPa along the longitudinal axis and a maximum compressive stress of 355 MPa along the transverse axis. DCT enhanced the weldment's tensile strength by up to 12% compared to as-welded samples, with a 6% increase compared to shallow cryogenic-treated (SCT) samples. Charpy impact testing indicated a value of 88 J in the fusion zone, which is 1.2% less than alloy 59 and 9% higher than 904 L. Tensile fracture analysis revealed ductile dimples, while impact fractography showed a mix of ductile dimples and brittle, glassy cleavage facets. [ABSTRACT FROM AUTHOR]

The steel/aluminum dissimilar metal welding plays a significant role in lightweighting automotive structures. However, the formation of hard and brittle intermetallic compounds (IMCs) in steel/aluminum welded joints severely compromises their mechanical performance. Nano ceramic particles such as TiC possess characteristics that inhibit the diffusion of Fe and Al, thereby exhibiting a significant advantage in suppressing IMCs formation in steel/aluminum welded joints. In this study, an optimized laser‐welding process is employed to investigate the mechanical properties of steel/aluminum dissimilar metal joints with different concentrations of TiC nanoparticles. It is aimed to determine the optimal TiC addition concentration by comparing the mechanical performance. Additionally, the inhibitory effect of TiC particles on the formation and growth of brittle Fe–Al IMCs is explored through an analysis of IMCs growth kinetics. In the research results, it is shown that the optimal TiC addition concentration is 1%. At this concentration, the tensile strength of the steel/aluminum welded joint reaches 98.29 MPa, showing a remarkable improvement of 32.65% compared to the sample without TiC addition. The addition of TiC particles suppresses the mutual diffusion between Fe and Al, reduces the generation of brittle IMCs, and enhances the mechanical performance of the steel/aluminum joint. [ABSTRACT FROM AUTHOR]

This study explores the influence of welding current, travel speed and gas flow rate on response parameters including ultimate tensile strength (UTS), percentage elongation (PE), microhardness (MH) and residual stress (RS) using face-centred central composite design (FCCCD). Dissimilar AA6061-T6 and AA7075-T6 plates were welded using an automated tungsten inert gas (TIG) process. Mathematical models were developed to predict the mechanical properties. High welding current or low travel speed enhanced the joint quality but raised residual stresses. At a welding current of 145 A, travel speed of 1.28 mm/s and gas flow rate of 18 l/min, the optimized UTS, PE, MH and RS were predicted to be 167.28 MPa, 10.25%, 69.61 HV and 65.49 MPa, respectively. Confirmation experiments were conducted to verify the model's practicality. The results indicate that travel speed has the greatest influence on the responses, followed by welding current, while the gas flow rate has the least effect. [ABSTRACT FROM AUTHOR]

The creep behaviour of dissimilar weld joint of 316LN SS-P91 steel when subjected to lower applied stresses (below 100 MPa) generally fails in a Type-IV pattern. The dissimilar weld joint was welded through shielded metal arc welding (SMAW) process with INCONEL as electrode, a nickel-based superalloy. An interrupted creep test was carried out at creep condition of 80 MPa −600 °C temperature. Interruption was done at two stages of creep, i.e. (a) mid of secondary and (b) start of tertiary. Microstructural evolution with respect to the hardness variation along various regions of P91 steel at interrupted and the failed specimen was done. A coarsening of hierarchical boundaries and M23C6 carbides was observed along HAZ region that has resulted with respect to time and temperature. [ABSTRACT FROM AUTHOR]

This study applies a 3D model built for butt dissimilar joints welded using a laser beam. The thermo-mechanical study of SS321 and Hastelloy C-276 uses a volumetric Gaussian heat source model. Ansys parametric design language code is executed in ANSYSTM software for the simulation. Using the CO2 laser beam welding procedure, the simulation's parameters serve as the experimental input procedures. We employ x-ray diffraction methods to quantify residual stresses in the weldments and evaluate the joint quality. The thermal results show that the fusion zone experiences maximum temperature, and the conduction occurs on the SS321 side. The residual stresses are tension at the fusion zone for simulation and experimentation. The welds exhibited full penetration and a consistent "Y" shape across all samples, indicating good structural integrity without internal defects. The factor of safety from the Finite Element Analysis (FEA) is 1.73, and the experimentation is 2.20. The residual stress varies by 21% from measured and FEA. Studies were carried out to characterize the weldments for their mechanical and metallurgical properties. Tensile tests confirmed that the weld zone's strength is higher than the parent metals. [ABSTRACT FROM AUTHOR]

AISI 316 stainless steel and ASTM A516 alloy steel weldment characteristics investigated according to filler materials and post weld heat treatment performance. The welding was performed using shielded metal arc welding (SMAW) with two types of filler metals, E7018 and E310, and PWHT was carried out at three temperatures: 600℃, 630℃, and 650℃. Welded joints' mechanical performance encompassed tensile and bending tests, and micro-hardness measurements, in addition to microstructural and fractographical examination employed for this purpose. Results evidenced that tensile strength and elongation of welded steel using E7018 electrode were 518 MPa and 28.1%, respectively, which showed relatively high strength. The results show steel welded with E310 electrode had higher mechanical properties, with the best balance between strength and ductility. In addition, post welding heat treatment improving mechanical properties by minimizing residual stress and refining grain structure. E7018 welded joints failure load increased to 86 KN after PWHT and the ultimate tensile strength increased to 525 MPa, further, microstructure analysis of optical microscope and scanning electron microscope shows PWHT has good effect on ductility improvement and hardness reduction. New microstructures with finer grain size and increased ferrite phase observed, which enhanced tensile and bend strength. [ABSTRACT FROM AUTHOR]

This journal discusses the process parameters of friction stir welding (FSW) for joining aluminum 5083 and aluminum 6061. The welding process was conducted to identify the optimal parameters for achieving high-quality joints. Based on the study's findings, the welding parameters of a tool rotational speed of 1400 rpm, a travel speed of 30 mm/s, and a tool tilt angle of 1° were identified as the best. Various tests, properties mechanical and microstructural evaluations, were conducted to assess the quality of the joints. The results indicated that the best tensile strength achieved was 180.45 MPa, corresponding to an efficiency of 78%, while the hardness value reached 65 Hv. Furthermore, the welding process under these parameters facilitated the refinement of grain size in the Weld Nugget (WN) zone, enhancing the bonding area between the two materials. This is attributed to the ability of FSW to break coarse grains into finer grains, leading to improved microstructural uniformity and consistent grain size due to the optimized process parameters. [ABSTRACT FROM AUTHOR]

This research examines the effect of thermomechanical and microstructural constituents on welding of AISI 316L (austenite stainless steel) and S275 steel. A Finite Element Model (FEM) was constructed using ANSYS 19.1, and an experimental study was conducted using the Rotary Friction Welding (RFW) process. It was determined that there is a genuine correlation between the simulation FEM and the experimental procedure with regard to the thermal profile and ultimate yield strength, particularly when a welding speed of 2,000 rev/min is employed. At that speed, the higher temperature recorded and calculated was 1,450 oC. The discrepancy between the numerical FEM and the experimental temperature profile for the peak temperature calculation was determined to be 2.78%. The mechanical analysis was conducted through tensile force calculations and experiments, the results of which indicated an estimated error of 12%. The calculated error for the ultimate yield strength of the various samples is less than 6% for tensile strength. Upon tensile testing, failure occurred in the S275 sample. The microstructure exhibited increases in Cr and Ni of 1.2% and 1.01%, respectively, in comparison to the base metal of 316L stainless steel. [ABSTRACT FROM AUTHOR]

The nuclear power plants in Eastern Europe face problems with supplies of spare parts manufactured according to the same Russian standards as the originals. Therefore, the dissimilar welds of original Russian steel 08Ch18N10T and substitutive 1.4541 were made and analyzed to consider the possibility of original steel replacement during the repairs. Two different filler wires were applied. The welds were subjected to cyclic thermal loading corresponding to the actual operating conditions of a nuclear unit, and their microstructure and mechanical properties were compared to the as-welded joints. An increase in weld metal microhardness induced by aging was found when the filler with higher C and Cr content was used. Although this could indicate possible ferrite decomposition, the detected changes in mechanical properties corresponded to the changes in homogeneous welds of the original steel. The strength requirements for the steel used in nuclear power plant devices were still matched. [ABSTRACT FROM AUTHOR]

The P91 martensitic steel and 304L austenitic stainless steels are two mainly used structural steels in power plants. The major problem in conventional multipass tungsten inert gas (TIG) welding of P91/304L steel is high heat input and joint distortion, increased cost and time associated with V groove preparation, filler rod requirement, preheating and welding in multiple passes, and labor efforts. Hence, in this study, a novel approach of robotically operated activated flux TIG (A-TIG) welding process and thin AlCoCrFeNi2.1 eutectic high entropy alloy (EHEA) sheet as the interlayer was used to weld 6.14 mm thick P91 and 304L steel plates with 02 passes in butt joint configuration. The joints were qualified using visual examination, macro-etching, X-ray radiography testing and angular distortion measurement. The angular distortion of the joints was measured using a coordinate measuring machine (CMM) integrated with Samiso 7.5 software. The quality of the A-TIG welded joints was compared to the joints made employing multipass-TIG welding process and Inconel 82 filler rod in 07 passes. The A-TIG welded joints showed significant reduction in angular distortion and higher productivity. It showed a 55% reduction in angular distortion and 80% reduction in welding cost and time compared to the multipass-TIG welded joints. [ABSTRACT FROM AUTHOR]

In-situ analysis of dissimilar laser welding in overlap configuration, which finds the most frequent application in industry, attracts an increasing attention of the research community. In the present work, emission spectroscopy and high-speed imaging were used to investigate the vapor plume behavior during a Yb:YAG laser pulse on the overlap joint between pure titanium and aluminum alloy A5754. A 15 ms long laser pulse was applied to the overlap joints, where titanium and then A5754 were placed on the top. Correlation of the obtained results with post-mortem observation of the impact zones and with a finite-element model of the keyhole evolution was performed. The combination of these approaches facilitated the development of a comprehensive phenomenological timelines of the processes, along with an evaluation of the efficacy of the employed online methods to discern the involvement of the bottom material with the melted zone. The considered configurations showed very different behavior: with reflective A5754 placed on top, the use of high laser power produced an intense keyhole propagation in bottom titanium plate, inducing rapid mix between the elements, while with titanium on top, the use of lower laser power produced prolongated keyhole stagnation at the interface with reflective A5754. High-speed imaging showed very fluctuating behavior of the plume, where the involvement of the bottom material was traduced either by a drastic drop of thermal and atomic emission after the keyhole tip enters the bottom A5754 plate, or by strong periodic bursts of Ti-rich jet after the keyhole reaches the bottom titanium plate. The results of emission spectroscopy were found in adequation with the involvement of bottom material into the melted zone, however, they are affected by plume fluctuations and by the pollution of the top plate by volatile elements. [ABSTRACT FROM AUTHOR]

The hybrid structures composed of Al and Ti materials have numerous applications in the aviation and automobile industries. In this work, studies involving friction stir welding of dissimilar AA2519-T87 and high purity titanium sheets are reported. A 2-mm thick sheets were welded by linearly varying the tool-offset position from the faying interface. The effect of tool-offset position on defect dynamics, formation of intermetallic compounds (IMCs), and fracture mechanism were investigated using optical microscope (OM), field emission scanning electron microscope (FESEM) fitted with energy-dispersive X-ray spectroscopy (EDS) facility, X-ray diffraction (XRD), tensile property and microhardness measurements. The maximum tensile strength of 297 MPa was attained in a defect free specimen. At extreme tool-offset distances, defects such as kissing bond, tunnels and joint line remnants were observed. The number density of IMCs increased with decreasing tool-offset positions, and Al3Ti and Al5Ti2 were observed at interfaces of all the samples. The variation in fracture mechanisms with defect analysis was studied and could be useful in fabrication of aircraft structures. [ABSTRACT FROM AUTHOR]

The present investigation is conducted to study the effect of the varying filler composition on microstructure and mechanical properties of the dissimilar metal welds of heat-resistant P92 steel and Ni-based superalloy Inconel 617 used for producing the boiler components in advanced ultrasupercritical (AUSC) power units. The dissimilar joint is prepared using the shielded metal arc welding (SMAW) technique using the electrode metals of Inconel 617 (ENiCrCoMo-1), Inconel 625 (ENiCrMo-3), and Inconel 82 (ENiCrFe-3). All the welds were made with the same welding parameters. It was witnessed from macrostructure and microstructural characterization that there was no evidence of cracks in weldments obtained by Inconel fillers. The EDS observation of the weld showed the presence of Ti(C, N) and NbC in ENiCrFe-3 weld, NbC and laves phase ENiCrMo-3 weld and Cr and Mo-rich phases (M23C6 and Mo6C) in ENiCrCoMo-1 weld. The room temperature tensile test showed the maximum (664 ± 11 MPa) and minimum (590 ± 10 MPa) ultimate tensile strength for the ENiCrCoMo-1 weld and ENiCrFe-3 weld, respectively. However, the ENiCrCoMo-1 weld showed failure from P92 BM, while in the other two welds, failure occurred in the weld metal. The hardness of the weld metal varied from top to root area as well as in transverse direction for each weld joint. The maximum hardness of the weld was 297 ± 12 HV for the ENiCrMo-3 weld and the minimum was 219 ± 9 HV for the ENiCrFe-3 weld. The microstructural characterization and mechanical testing confirmed that ENiCrCoMo-1 filler was the best choice among all the fillers for making the dissimilar joint of P92 and Inconel 617. [ABSTRACT FROM AUTHOR]

This study aims to explore the effects of various pre- and post-weld heat treatments (PWHTs) on the microstructural and mechanical properties of dissimilar aluminium alloys, namely AA7075 and AA2024, joined through rotary friction welding. The joints were rigorously evaluated through multiple characterization methods, revealing no signs of cracking or incomplete bonding. This study observed that dissimilar joints between AA7075 and AA2024 alloys showed increased flash formation on the AA7075 side due to its lower melting point relative to the AA2024 alloy. Various zones within the weld region were identified, such as the dynamic recrystallized zone (DRZ), the thermo-mechanically affected zone (TMAZ)—which includes TMAZ-1 with elongated grains and TMAZ-2 with compressed or distorted grains—the heat-affected zone (HAZ), and the base metal (BM) zone. Of all the welding conditions examined, the post-weld heat-treated (PWHT) AA2024/AA7075 joint produced by rotary friction welding showed the highest strength, with a yield strength (YS) of 305 ± 2 MPa and an ultimate tensile strength (UTS) of 477 ± 3 MPa. This improvement in strength can be attributed to the significant strengthening precipitates of MgZn2 (found on the AA7075 side), θ-Al2Cu, and S-Al2CuMg (found on the AA2204 side) formed during post-weld ageing. Notably, all dissimilar welds failed in the HAZ region on the AA2024 side due to coarse grain formation, identifying this as the weakest area. [ABSTRACT FROM AUTHOR]

The development of oscillating laser beam welding (OLBW) provides an opportunity to improve the weld formation of dissimilar stainless steels. In this paper, the influence of oscillating amplitude on the weld formation, microstructure, and mechanical properties of dissimilar 430/5Cr15MoV stainless steel was studied. The results showed that the weld morphology became smooth and uniform with an increase in the oscillating amplitude, and there was no obvious defect on the surface. The formation mechanism of weld overflow defects on the weld surface was discussed. The width of the weld metal increased with an increase in oscillation amplitude. The influence of beam oscillation on the microstructure of the weld center was significant, i.e., the proportion of equiaxed grains in the center of the welds increased as the oscillation amplitude increased. The maximum microhardness of the weld was obtained at an amplitude of 1.5 mm. Moreover, the tensile strength of the welds reached 477 MPa, which was comparable to the tensile strength of the 430 stainless steel base material. The fracture modes of all welds were typical ductile fractures, which suggests that the oscillation amplitude had a minor effect on the fracture mechanism of the welds. This study provided a new approach to welding dissimilar stainless steels and offers guidance for the selection of an optimum oscillation amplitude. [ABSTRACT FROM AUTHOR]

Magnetic pulse spot welding based on a field shaper can effectively achieve spot welding of dissimilar metal plates by using the multi-turn flat coil and magnetic gathering through the field shaper. Through existing experimental research, it has been found that when using this method for welding, there will be a serious bulging problem in the center of the welding area, which will affect the flatness and aesthetics of the welding area, thereby affecting its application range. To solve this problem, this work proposes two different welding methods for welding dissimilar AA1060 aluminum and SS304 steel plates with a thickness of 1 mm: one based on the center opening of the flying plate and the other based on the pre-deformation of the flying plate. The causes of bulging and the effects of discharge voltage, welding gap, and inner hole radius of the field shaper on bulging size were studied. The cross-sectional morphology and mechanical properties of welded joints obtained by two welding methods were studied through numerical simulation, cross-sectional analysis, and tensile testing. The results indicated that both welding methods can successfully eliminate the bulging problem, and the point welding method based on the center opening of the aluminum plate can also reduce the minimum welding energy required for effective welding and improve welding efficiency. In addition, microscopic analysis results showed that a waveform composite interface was formed at the welding interface of the joint, and the connection performance of the welded joint was good. These two welding methods can also be extended to the welding of other dissimilar metal plates, which is of great significance for the industrial application of magnetic pulse spot welding technology based on field shaper. [ABSTRACT FROM AUTHOR]

Dissimilar welding of duplex stainless steel (DSS) with high-strength low alloy (HSLA) was more complicated since they were utilized in automotive and aerospace design, which needed components with lower weight, higher tensile strength (TS), hardness, corrosion resistance. In this research paper, the main objective was to establish a gas tungsten arc welding process, on a 60∘ angle double groove on both sides of DSS and HSLA, using three different filler metals ER2594, ER70S2 and ER304. The welded surfaces of the specimens were analyzed to assess the microstructural characterization using SEM and Edax, and they were also tested to determine their mechanical and corrosion characteristics. In comparison to microstructural characterization, Mn and Si combination decreased the surface defects in the weldment made by ER2594. The determination of mechanical properties revealed that specimen A produced by ER2594 was superior to other specimens B and C, in terms of yield stress, TS and hardness. Similarly, improved corrosion resistance was achieved by the larger presence of Cr along with Ni in ER2594. In the welded joint, Ni combined with an appropriate proportion of other alloying elements in ER2594 enabled effective control over the ferrite-austenite phase balance, which was crucial for achieving the necessary combination of properties and weldability designed for particular applications. Among the three filler metals, ER2594 showed better microstructure uniformity, enhanced TS, hardness and superior corrosion resistance. [ABSTRACT FROM AUTHOR]

With the growing demands in several sectors such as the automotive, biomedical, construction, shipbuilding, aerospace, and other manufacturing units, employment of welding techniques has observed a rapid boom in recent times. Laser welding technique is one such recent sign of progress in the fabrication field. Laser beam welding is a radiant energy welding process widely adapted to join a variety of metals and nonmetals. The demand for the dissimilar material welding increases with the increase in industrial needs. Several severe challenges need to be overcome to have such dissimilar welded components mainly as the significant difference in melting point, different combinations of mechanical, metallurgical, chemical, and thermal properties. The present approach attempts to study the weldability of steel and its alloys with other metals and parametric effects on mechanical and microstructural properties. The study reveals that the laser beam offset plays a vital role to achieve sound quality welded joint with desirable weld strength. It has been found that 0.32 mm beam offset generates 243 MPa ultimate tensile strength in the 316L to TC4 dissimilar welds. Again, the addition of interlayers also improves the joint strength of both steel‐to‐aluminum and steel‐to‐titanium dissimilar welded joints. [ABSTRACT FROM AUTHOR]

In this study, fiber laser butt welding was performed on a 6 mm thick Ti-6Al-3Nb-2Zr-1Mo alloy and 10CrNi3MoV steel using two interlayer configurations, with the innovative introduction of an external alternating magnetic field. The microstructure, element distribution, and mechanical properties of the welded joint were investigated through various methods including scanning electron microscopy, energy-dispersive X-ray spectrometer, and X-ray diffraction. Results showed that joints with two interlayer configurations were present in an interfacial layer with non-uniform thickness and poor mechanical properties, due to the heterogeneous heat distribution in the thickness direction and the mixing of elements during the laser welding process. Applying an alternating magnetic field facilitated convection of the molten pool from center to sides, which accelerated forced convection in both vertical and horizontal directions leading to more uniform heat distribution as well as element distribution resulting in a significant reduction or disappearance of unmelted Cu for different interlayers, while also reducing the thickness of the interfacial layer at the upper part of the joint and significantly improving tensile strength by 5.9% and 8.3%, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT Dissimilar metal welds are utilized in the energy industry to connect two materials with different material characteristics. In the case of nuclear power plants, the connected materials tend to be low‐alloyed steel and high‐alloyed material. Despite different material and corrosion properties, under the proper environmental conditions, the used construction materials and weld metals are protected either by a passive layer or by a high‐temperature oxide. Although dissimilar metal welds are used in both primary and secondary circuits, the most frequently documented damage is in the secondary circuit, where, in addition to material heterogeneities, local environmental heterogeneities may form. For dissimilar metal welds in WWER nuclear power plants, a water–water energetic reactor, a subtype of pressure water reactor, we note two main types of attack near the dissimilar fusion boundary: on the carbon steel side or on the high‐alloyed weld metal side (X10CrNiMoN16‐25‐6). The possible causes of the latter “atypical” corrosion attack are debated and can be generalized as a consequence of change of the grain boundary condition. [ABSTRACT FROM AUTHOR]

ABSTRACT 6016‐T4 aluminum (Al) alloy plate was butt welded to the cold‐rolled steel plate by a friction stir welding (FSW) technique, and the fatigue properties of Al/steel dissimilar welds were investigated. Some dissimilar welds were die‐press formed to the hat shape, and specimens were sampled from the corners of the hat shape, where severe plastic deformation occurred by the die‐press forming. The die‐press‐formed samples had better tensile strengths and hardness than the as‐welded ones because of the work hardening. It indicates that the die‐press forming is applicable for the Al/steel dissimilar welds. However, large voids were formed around the steel fragments dispersed into Al matrix by die‐press forming. Those voids acted as the fatigue crack nucleation sites, thus reducing the fatigue lives of the die‐press‐formed specimens. When the bottom side of the welds experienced tension plastic deformation, the fatigue strength was the lowest. [ABSTRACT FROM AUTHOR]