Dissimilar Joints Research Articles

Enhancing microstructure and mechanical properties of dissimilar TIG welded duplex 2205 and Ni-based inconel 718 superalloy through post weld heat treatment

In demanding applications, maintaining structural integrity in dissimilar welded joints like those between duplex stainless steel and Ni-based superalloys requires achieving the best possible mechanical properties. This work examines the impact of post-weld heat treatment (PWHT) on the mechanical characteristics of joints made via double-sided tungsten inert gas (TIG) welding. The dissimilar welded joint was investigated by exposing it to the PWHT for 12 h at 650 °C. Reducing the negative impact of heat generated by welding on the mechanical characteristics and microstructure of the fusion zone was the main goal. To study for changes in the microstructure before and after PWHT, optical microscopy and scanning electron microscopy methods were used for microstructural analysis. To determine the effect of PWHT on the welded joints, mechanical properties such as tensile strength, toughness, and ductility were also assessed. The mechanical properties showed significantly enhanced characteristics and refined grain structures in the fusion zone.

Eliminating Cu-rich intermetallic compound layer in dissimilar friction stir welding of 304 stainless steel and 2219 Al alloy via ultralow rotation speed

The formation of the Cu-rich intermetallic compound (IMC) layer at the interface has always been the critical bottleneck of welding steel to 2xxx series Al alloys with high Cu content. In this study, we successfully eliminated the Cu-rich IMC layer by using a modified friction stir welding (FSW) method under an extremely low rotation speed of 200 rpm. At an appropriate thickness difference of the welded plates, defect-free FSW joint of 304 stainless steel to 2219Al alloy with high tensile strength of 210 MPa was obtained, and the sample failed in the 2219Al side rather than at the interface. It is found that a continuous Al-Fe-O amorphous layer of ∼10 nm in thickness formed at the steel-Al interface, and only few Al2Cu IMC particles existed at the interface. The Al2Cu particles were blocked by the amorphous layer and cannot directly contact the steel, consequently realizing the excellent metallurgical bonding between the steel and 2219Al alloy. It is anticipated that this work will provide a feasible strategy for fabrication high-quality dissimilar joints between steel and 2xxx series Al alloys, which can broaden the application of steel-Al joints in the industries.

Investigation on microstructural and mechanical integrity of GTAW dissimilar welded joint of IN 718/ASS 304L using Ni-based filler IN 625 using EBSD and DHD techniques

The current study investigates the relationship between the microstructural and structural characteristics of dissimilar gas tungsten arc welding (GTAW) between Inconel 718 (IN 718) and austenitic stainless steel 304L (ASS 304L) using Inconel 625 (IN 625) as a filler material. The microstructural characterization of the dissimilar weld includes the application of an optical microscope (OM), field emission scanning electron microscopy (FE-SEM) including energy dispersive spectroscopy (EDS), and electron backscatter diffraction (EBSD). The optical and FESEM analysis of the base metals (BM) indicates the austenitic nature of the IN 718 BM matrix, which incorporates strengthening precipitates γ′ and γ'' distributed throughout the Nickel matrix. In contrast, the ASS 304L BM exhibits an austenitic microstructure along with twins. Moreover, IN 625 weld metal exhibits austenitic microstructure in the form of cellular, columnar, and equiaxed dendrites. Elemental segregation demonstrates the existence of Nb, and Mo-rich carbides, including the laves phases at the interdendritic regions of the IN 625 weld zone and IN 718 Heat-Affected Zone (HAZ). Ferrite stringers were noticed in the HAZ of ASS 304L. EBSD analysis shows the improved texture of the weld zone exhibiting fine equiaxed recrystallized microstructures. EBSD/Kernel average misorientation (KAM) micrographs reveal the existence of high strain at the weld metal grain boundaries. Vickers microhardness assessment of the dissimilar weld demonstrates the high hardness of 257.5 HV for the IN 625 weld zone because of the occurred NbC, laves phases, and Mo-rich carbides. Room temperature tensile characterization shows the failure of tensile specimens from ASS 304L BM reflecting the high strength of the IN 625 weld metal (662 MPa). Tensile tests at high temperatures were performed at 550 °C, 600 °C, and 650 °C. High-temperature tensile result exhibits a higher tensile strength of IN 625 weld zone than the ASS 304L BM, as the tensile specimens fails from 304L BM. The specimen exposed at 550 °C exhibits the highest tensile strength of 388 MPa. The Charpy impact toughness test was conducted, with notches at the HAZ of ASS 304L, HAZ of IN 718, and the weld center being evaluated. The toughness value of the weld metal decreases (99 J) due to occurrence of the secondary precipitates. To analyze residual stress, the deep hole drilling (DHD) technique was used, which revealed that the peak residual stress (230 MPa) is induced at 6 mm from the weld surface and falls into the tensile stress category.

Optimization of process parameters of cold metal transfer arc welding of AA 6061 aluminium Alloy-AZ31B magnesium alloy dissimilar joints using response surface methodology

The fabrication of dissimilar metal joints, particularly between AA 6061 aluminum alloy (Al) and AZ31B magnesium alloy (Mg), poses significant technical challenges due to their distinct metallurgical characteristics and the inherent difficulties associated with welding such materials. These challenges include the propensity for intermetallic compound formation, thermal cracking, and differences in thermal and mechanical properties between the two alloys. Cold Metal Transfer (CMT) welding, known for its low heat input and controlled metal transfer, offers a potential solution to these issues. However, optimizing the process parameters to ensure strong, defect-free joints requires a systematic approach. This study aims to optimize CMT welding parameters using parametric mathematical modeling (PMM) to produce high-strength Al and Mg dissimilar joints and to study the effects of CMT parameters on tensile strength (TS) and weld metal hardness (WMH), as well as the microstructural features of AA 6061 aluminum alloy/AZ31B magnesium alloy (Al/Mg) dissimilar joints. Al/Mg dissimilar butt joints were produced by the CMT process using ER4043 as filler wire. CMT, a low-heat input welding technique, was used to mitigate issues such as intermetallic compounds (IMCs), wider heat-affected zone (HAZ), and distortion. The CMT parameters, particularly wire feed speed (WFS), welding speed (WS), and arc length correction (ALC), were optimized using response surface methodology (RSM) to maximize the TS and WMH of the Al/Mg dissimilar joints. Polynomial regression was employed to create PMMs that integrated these CMT parameters to forecast the TS and WMH of the joints. An analysis of variance (ANOVA) was applied to assess the feasibility of the PMMs. The results indicated that the Al/Mg dissimilar joints, produced using a WFS of 4700 mm/min, a WS of 280 mm/min, and an ALC of 10%, exhibited higher TS and WMH values of 33 MPa and 95.8 HV, respectively. The PMMs provided precise forecasts for the TS and WMH of the Al/Mg joints with an error rate of less than 1% and a confidence level of 97%.

Microstructure and corrosion behavior of A390-10 wt% SiC composite-AA2024-T6 aluminum alloy dissimilar joint: Effect of post-weld heat treatment

The weldability of aluminum matrix composites to other materials, such as aluminum alloys, is an essential point in expanding the use of these materials. This study investigated the effect of rotational speed and post-weld heat treatment on the microstructure, mechanical properties, and corrosion behavior of A390-10 wt% SiC composite/AA2024-T6 aluminum alloy dissimilar joint. Friction stir welding is performed using a square frustum pyramid pin tool with a rotational speed of 400–1200 rpm and a traverse speed of 40 mm/min. Results found that a surface groove formed on the weld crown at a rotational speed lower than 800 rpm due to insufficient material flow. Also, the tunnel defect formed on the advancing side at a rotational speed higher than 1000 rpm due to the turbulent flow of material. By increasing rotational speed from 800 to 1200 rpm, the average grain size of the advancing and retreating sides increased by 41.1 and 46.3 %, respectively. Compared to AA2024-T6 and A390-10 wt% SiC composite base metals, the average hardness of the stir zone of the joint fabricated by the rotational speed of 800 rpm increased by 8.4 and 38.2 %, respectively. By increasing the rotation speed from 800 to 1000 rpm, the yield strength and ultimate tensile strength decreased by 6.8 and 6.5 %, respectively. By decreasing rotational speed from 1000 to 800 rpm, the elongation and corrosion resistance decreased by 5.4 % and 34.7 %, respectively. After post-weld heat treatment, the hardness, yield strength, ultimate tensile strength, and corrosion resistance increase 15.9, 12.7, 7.8, and 28.9 %, respectively.

Microstructure, Corrosion and Mechanical Properties of Medium-Thick 6061-T6 Alloy/T2 Pure Cu Dissimilar Joints Produced by Double Side Friction Stir Z Shape Lap-Butt Welding

A novel double side friction stir Z shape lap-butt welding (DS-FSZW) process was proposed to achieve excellent mechanical properties of Al/Cu medium-thick dissimilar joints. The influence of welding parameters on weld microstructure and properties of DS-FSZW joint were systematically investigated. It indicated that defect-free medium-thick Al/Cu DS-FSZW joint could be achieved under an optimal welding parameter. DS-FSZW joint was prone to form void defects in the bottom of the second-pass weld. The recrystallization mechanisms at the top and middle of the weld nugget zone (WNZ) were continuous dynamic recrystallization (CDRX) and geometric dynamic recrystallization (GDRX). While the major recrystallization mechanism at the bottom of the WNZ was GDRX. DS-FSZW joint of the optimal welding condition with 850 r/min-400 mm/min was produced with a continuous thin and crack-free IMCs layer at the Al/Cu interface, and the maximum tensile strength of this joint is 160.57 MPa, which is equivalent to 65.54% of pure Cu base material. Moreover, the corrosion resistance of Al/Cu DS-FSZW joints also achieved its maximum value at the optimal welding parameter of 850 r/min-400 mm/min. It demonstrates that the DS-FSZW process can simultaneously produce medium-thick Al/Cu joints with excellent mechanical performance and corrosion resistance.

Microstructure and mechanical properties of a dissimilar metal welded joint of Inconel 617 and P92 steel with Inconel 82 buttering layer for AUSC boiler application

The application of the novel dissimilar metal welded (DMW) joint, utilizing Inconel 617 and P92 steel, was showcased in the advanced ultra-supercritical (AUSC) boiler. The work has been performed to investigate the effect of Inconel 82 (ERNiCr-3) buttering layer on microstructure and mechanical properties (high-temperature tensile strength, impact strength and microhardness) of gas tungsten arc welded (GTAW) dissimilar joint between Inconel 617 and P92 steel fabricated using the Inconel 617 (ERNiCrCoMo-1) filler. For optical microscopy and scanning electron microscopy (SEM), samples were machined along a transverse direction which comprised the butter layer, weld metal, and heat-affected zone of both sides. The energy-dispersive X-ray spectroscopy (EDS) was used to map the interface of the buttering layer and weld metal and butter layer and P92 steel. The high-temperature tensile testing and Charpy impact testing at room temperature were conducted for the integrity assessment of the welded joint. The examination of microstructure and hardness revealed that the buttering layer of Inconel 82 filler successfully mitigated a significant portion of the brittle martensitic microstructure from the coarse-grained heat-affected zone (CGHAZ), along with hardness peaks on the side of P92 steel. The conventional method of DMW joint fabrication, without the use of a buttering layer, has been demonstrated to be less favourable compared to the new fabrication method, which incorporates a buttering layer. The TiC/NbC carbides were identified in the Inconel 82 buttering layer, whereas M23C6 and Mo6C carbides were found in the Inconel 617 filler weld. Near the interface of the Inconel 82 buttering layer and P92 steel, the formation of peninsula and island structures, as well as Type I and Type II boundaries, were confirmed. Additionally, element diffusion of Ni, Cr, and Fe was observed. The tensile test results indicated an ultimate tensile strength of 620 ± 4 MPa and % elongation of 19 ± 4 % at room temperature, with fracture occurring in the buttering layer near the interface of the buttering layer and P92 steel. At temperatures of 550 °C and 650 °C, the ultimate tensile strength decreased to 448 MPa and 326 MPa, respectively, with fractures occurring in the P92 steel, irrespective of temperature. The hardness of the Inconel 82 buttering layer and Inconel 617 filler weld were 219 ± 10 HV and 248 ± 11 HV, respectively. The Charpy impact toughness of the Inconel 82 buttering layer and Inconel 617 filler weld were 138 ± 6 J and 115 ± 4 J, respectively. The study comprehensively investigates and discussed the correlations between microstructure and mechanical properties.

Microstructure and Properties of Dissimilar Butt Joints of Aluminum to Copper by Cold Metal Transfer with Preheating

Microstructure and Properties of Dissimilar Butt Joints of Aluminum to Copper by Cold Metal Transfer with Preheating

The influence of tool shoulder size and plate position on the characteristics of friction stir welded different aluminum alloys

ABSTRACT Welding is a main manufacturing method for fabricating various engineering components. Fusion welding techniques encounter solidification associated problems while joining light weight structures. Friction stir welding is a solid state welding technique that is developed to address these shortcomings. As the superior conductive properties of AA6101-T6 and AA1350 aluminum alloys, they are frequently utilized in electrical industries. The goal of this study is to examine how the plate position and tool shoulder diameter (D) affect the qualities of these dissimilar Al-alloys joints. It is discovered that plate positioning is the most influential welding parameter in determining the tensile properties of weldment. Furthermore, the joint fabricated with AA6101-T6 as an advancing side material and a 15 mm tool shoulder diameter produces sufficient weld reaction temperature, better plastic flow and tensile properties. However, the joint fabricated with AA1350 as an advancing side material and 12 mm tool shoulder diameter generates inadequate reaction temperature, poor plasticization, and tensile properties. The formation of precipitates as well as the interface layer at the weld nugget is greatly dominated by the tool shoulder size, which affects the wear properties of weldment.

Al interlayer enhanced interfacial strength of ultrasonically welded copper-titanium dissimilar joints

This study investigated the ultrasonic welding of Cu-Ti joints, revealing that the interfacial strength originated from mechanical interlocking. However, strength was diminished owing to interface-adjacent crack initiation due to excessive plastic strain. Introducing an Al interlayer prevented base metal damage with more frictional heat, and enhanced interfacial strength by 26%.

Characterization of the spin arc welding technique for dissimilar materials Hastelloy C-2000 and C-276

Hastelloy C-2000 and C-276 are primarily employed in the petrochemical and pharmaceutical industries. Finding an effective way to combine these alloys is still a complex task in industry. The main focus of this study is to investigate the potential efficacy of the spin arc welding process on Hastelloy C-2000 and C-276. The welding process was carried out under various conditions, such as weld current, spinning speed, and spin diameter. ERNiCrMo-4, with a diameter of 1.2 mm, was employed as a filler. Optical microscopy, XRD and FESEM were used for microstructural examination. The mechanical properties of the welded samples were critically analyzed. The results of the ultimate tensile strength (UTS), hardness value (HV), and impact tests of spin arc welding were compared with those of the multipass pulsed current gas tungsten arc welding process (MPCGTAW). In spin arc welding, Hastelloy C-2000 and C-276 exhibited higher UTS, HV, and toughness compared to MPCGTAW because there was no secondary TCP phase formation in the weld centre and hot cracking in spin arc weldments. Additionally, compared to MPCGTAW, the elongation with spin arc welding was noted to be lower. Moreover, microstructural analysis revealed no evidence of grain segregation, which may have contributed to the improved UTS and HV of the materials during spin arc welding. Thus, spin arc welding proves to be superior for dissimilar Hastelloy joints of C-2000 and C-276.

Failure of dissimilar QP980/DP600 advanced high strength steels resistance spot welds

This study investigates the microstructure, failure characteristics, and mechanical properties of dissimilar resistance spot welds between QP980 quenching and partitioning steel and DP600 dual phase steel. The dissimilar spot welds exhibited a heterogeneous microstructure, with a fusion zone predominantly composed of martensite, significantly overmatching both base materials. A fully martensitic structure with grain size gradient was observed in the upper-critical heat affected zone (UCHAZ) on both sides of the dissimilar joint. In the sub-critical heat affected zone (SCHAZ), no significant phase transformation occurred on both sides. However, at high welding currents, a slight tempering of pre-existing martensite was detected on the QP980 side resulting in a minor hardness drop in this zone. There was a critical welding current at which the failure mode was changed from interfacial mode to pullout mode. The dissimilar QP/DP joint showed a lower tendency to fail via interfacial failure mode compared to similar QP/QP and DP/DP joints, attributed to a higher fusion zone hardness overmatching factor and greater nugget rotation. Pullout failure of dissimilar QP/DP combination was assessed in detail through interrupted tensile shear test. It was found that failure at stronger QP980 side occurred by ductile cracking mechanism initiated from the notch tip, while failure at softer DP600 side occurred by through-thickness localized necking. The former was found to be the prior failure mechanism controlling the load bearing capacity of the dissimilar joint. The mechanical properties of dissimilar QP/DP joints were discussed in terms of peak load and energy absorption, and then were compared to those of similar DP/DP and QP/QP joints in the light of weld microstructure and failure mechanisms.

Morphological and plastic deformation study on impact strength of AA7075 and 316LSS in friction stir welding

The Impact of Friction stir Welding (FSW) in two dissimilar materials particularly in 316L Stainless Steel (SS) and AA7075 is very challenging due to its inherent properties when exposed to elevated temperature environment. The 316L SS is the grade generally used for deep drawing process of various SS applications. The Aluminum which generally provides the oxide formation when subjected to friction stir welding and develops the proper patter of stir zone in the heat affected environment. General preheating is required for SS before exposing it to the FSW process. The temperature might be of around 350˚ C is required for SS, so that the developmental of thermal gradient and weld quality between the two metals will achieve in proper pattern. As the Impact study will provides the aluminum and Stainless steels in the welded zone or Heat Affected Zone (HAZ) with different cracking and nucleation behavior. This phenomenon enhances the mechanical property in the Aluminum zone. After the various literature study, the FSW welded region of the metal provides improper pattern due to same start of welding at the mid of the dissimilar joints. In this phenomenon the FSW can start its process from the steel side of the joint and completing it to the Aluminum joint will reduces the growth of void and nucleate the agglomeration of oxides fromAA7075 to 316LSS.

Research on the interfacial microstructure and mechanical properties of glass/Mg joint prepared by anodic bonding and vacuum diffusion bonding

The joining of glass and Mg by a combination of anodic bonding and vacuum diffusion bonding with Al as the interlayer was achieved in one step. The microstructures of glass/Mg dissimilar joints were analyzed using optical microscopy, SEM, and EDS. The results show that the bonding interface was joined well without any voids and cracks. Na+ and Ca2+ depletion regions would be produced in the glass near the Al foil, where the width of the Na+ depletion region was larger than that of the Ca2+ depletion region. In addition, the content of Al element in the depletion regions increased, and the diffusion of Al into the depletion regions was responsible for the successful glass/Al bonding process. Al3Mg2 and Al12Mg17 intermetallic compound (IMC) layers were formed between the Al and Mg. The anodic bonding process and the vacuum diffusion bonding process were independent of each other: and the thickness of the IMC layer increased with the increase of the diffusion bonding time, while the width of the Na+, Ca2+ depletion region remained constant; Meanwhile, the variation of the anodic bonding parameters only affected the width of the depletion layer and had no effect on the thickness of the Al3Mg2 and the Al12Mg17 IMC layer. The fracture position of the sample changed from the Al/Mg bonding interface to the glass/Al bonding interface as the thickness of the IMC layer increased. The maximum tensile strength of 14.6 MPa was obtained by vacuum diffusion bonding at 450 °C for 20 min and anodic bonding under 400 °C and 800 V.

Microstructure and mechanical assessment of Inconel 625 and AISI 904L dissimilar joints using high-density welding technique for pressure vessels

The dissimilar bimetallic joints of 5 mm thick Inconel 625 and AISI 904L were accomplished through the high-density fiber laser welding (LBW) process. The metallurgical investigation ensured the micro-segregation of Mo and Nb in the dendritic and inter-dendritic regions along with the formation of secondary topologically closed packed (TCP) phases. In addition to the metallurgical studies the Kernal average misorientation (KAM), Schmid factor (SF), and nucleation of the new grains were investigated through Electron backscattered diffraction (EBSD) analysis. The tensile strength opined the occurrence of failure on the 904L side, away from the weld seam ensuring that the joints have a higher strength. The notch tensile showed a higher strength of 678 ± 4 MPa in the weld zone than that of the 904L base alloy. The Charpy V notch studies showed a drastic decrease in the impact toughness with 38 ± 2 J as compared to the base alloys under sudden impact loading at room temperature (RT).

Study of microstructure and mechanical properties of SA553/SA537 steels joints using multi-pass welding for pressure vessels application

In this study, gas metal arc welding (GMAW or MIG) process was investigated for similar and dissimilar joints of SA553 and SA537 steel plates in different thicknesses with E NiCrMo-3 filler metal and 0–3 panel joint design that joined pressure vessels body to manholes. In order to examine the metallurgical behavior of the weld, optical and scanning electron microscopies were used. The effect of cooling rate (∂T∂t) on microstructure, strength and impact energy (cryogenic fracture toughness) were examined. By doubling the thickness (6–12 mm), the heat transfer rate or cooling rate (∂T/∂t) increased 4 times. Therefore, the strength and impact energy for the similar welding joint SA553 increased by about 8 % and for the similar welding joint SA537 by about 5 %. For dissimilar weld joints with different thicknesses, strength and impact energy are caused by the type of base metals and the different cooling rates of each base metal. Due to the high elongation of the E NiCrMo-3 electrode (30 %), there was continuous plastic deformation during bending tests. Also, by carrying out radiographic tests, the absence of cracks in welding structures was confirmed.

Microstructural evolution and the nanomechanical response of fiber laser-welded dissimilar joints of AA7075–Ti–6Al–4 V alloys using Ag as an interlayer

Microstructural evolution and the nanomechanical response of fiber laser-welded dissimilar joints of AA7075–Ti–6Al–4 V alloys using Ag as an interlayer

Comparative Analysis of Microstructure Evolution and Mechanical Properties of Dissimilar Welded Joints of AA7075/AA6061 via Friction Stir Welding, Tungsten Inert Gas Welding, and Tungsten Inert Gas + Friction Stir Processing

Comparative Analysis of Microstructure Evolution and Mechanical Properties of Dissimilar Welded Joints of AA7075/AA6061 via Friction Stir Welding, Tungsten Inert Gas Welding, and Tungsten Inert Gas + Friction Stir Processing

Influence of electrode current on mechanical and metallurgical characteristics of hot wire TIG welded SS304HCu austenitic stainless steel and P91 ferritic steel dissimilar joints

Influence of electrode current on mechanical and metallurgical characteristics of hot wire TIG welded SS304HCu austenitic stainless steel and P91 ferritic steel dissimilar joints

Analyzing microstructural evolution and wear behavior of friction stir welded dissimilar joints of SS304 and 2024-T3 Al alloy

This study employs friction stir welding (FSW) on SS304 and 2024-T3 Al alloy to enhance the microstructure and wear resistance of the resulting joint. FSW yielded an ultra-refined microstructure with a 4.2 µm average grain size, achieved through severe plastic deformation. In the dry sliding reciprocating wear test, specific wear rates for the base materials Al alloy, SS304, and FSWed specimens were determined to be 9.251 × 10−17 m3/Nm, 4.824 × 10−17 m3/Nm, and 2.072 × 10−17 m3/Nm respectively. Notably, the FSWed specimen exhibited an improved wear behavior, showing increased stability in the tribolayer and a reduced occurrence of severe delamination. The enhancements result from grain refinement and the inclusion of finely dispersed stainless steel (SS) particles, comprising around 5–6 % of the material, with an average grain size of 1 µm to 1.2 µm, within the stir zone (SZ), encased by thin layers of FeAl3 and Fe3Si. These factors contribute to the heightened microhardness of the specimen and a decrease in wear rate.