Mechanical Properties Of Dissimilar Welds Research Articles

Microstructure evolution and enhanced cryogenic toughness of laser welded dissimilar SA645/AISI304L joints via intercritical tempering

In this study, we explored the impact of intercritical tempering on the microstructural evolution and mechanical properties of dissimilar welds formed through laser welding between 5%Ni steel (SA645) and austenitic stainless steel (AISI304L). Upon tempering at 500 °C, reversed austenite manifested within the weld metal. The volume proportion of reversed austenite in weld metal at room temperature increased first, exhibiting a maximum (∼10%) at ∼600 °C, and then decreased with increasing tempering temperature, which was associated with the diminished stability of austenite. Due to the change in tempering temperatures, two distinct types of reversed austenite were present, with one being located at the high-angle grain boundaries and the other within the martensite blocks. As the tempering temperature increased, the weld metal hardness decreased, reaching a minimum of ∼306 HV at 600 °C, and then increased. The dislocation density within the martensite matrix and the quantity of reversed austenite are the crucial factors to determine the hardness of weld metal. The cryogenic impact toughness of weld metal increased at first and then decreased as the tempering temperature increased. The maximum of ∼40 J for the cryogenic impact toughness was obtained when tempering at 600 °C. The low-temperature impact toughness of the weld metal was determined by the synergy of the TRIP effect of reversed austenite, the compatible deformation capability of dual-phase structure, and the crack propagation behavior.

Multi-objective optimization and evolution of dissimilar welding process between Cr-Mo steel and austenitic stainless steel for power plant application

In this study, response surface methodology (RSM) was employed to optimize the welding parameters’ effects on mechanical properties of dissimilar welds between Cr-Mo steel grade (P11) and austenitic stainless steel (AISI 316LN). To determine the best welding parameters, variance analysis (ANOVA), desirability function, and perturbation analysis were used to create regression models and identify the significant parameters influencing tensile strength and hardness gaps in the weld joints. The results indicated that welding speed is the most significant parameter affecting both the austenitic hardness gap and tensile strength, while gas flow has the most significant impact on the hardness gap of Cr-Mo steel. Furthermore, welding speed positively influences the mechanical properties of dissimilar weld, whereas welding current has a slight negative effect on tensile strength. The optimum welding parameters were found to be 130 A for welding current, 70 mm min−1 for welding speed, and 13 l min−1 for welding gas flow, resulting in hardness gap values of 18.10 HV (Stainless steel side), 27.38 HV (Cr-Mo steel side), and a tensile strength of 453.90 MPa. The optimum parameter effect is concentrated at the weld interfaces between the fusion zone and the heat-affected zone. This effect led to limitations in grain coarsening, a reduction in the martensite and delta ferrite phase percentages, a slight increase in the bainite ratio, and a decrease in carbide precipitations. As a result, a homogenization of strain distribution in the optimum weld was achieved, leading to ductile fracture in Cr-Mo steel.

Microstructure and Mechanical properties of Dissimilar Welds of Duplex and API Steel for Offshore Applications

Microstructure and Mechanical properties of Dissimilar Welds of Duplex and API Steel for Offshore Applications

Enhancement of mechanical properties through modified post-weld heat treatment processes of T91 and Super304H dissimilar welded joint

The work is focused on examining the influence of heat treatment modification during post-weld heat treatment on microstructure and mechanical properties of dissimilar welds of T91 and Super304H. Tungsten inert gas (TIG) welding was employed with ERNiCr-3 as filler to prepare the dissimilar metal welds. Following that, two post-weld heat treatments (PWHTs) were performed, viz. post-weld normalizing and tempering (PWNT) and post-weld direct tempering (PWDT). The latter was performed at 760 °C for 1 h, while the former was carried at 1050 °C for 30 min (normalizing) and then tempered at 760 °C for 1 h. The microstructural examination using scanning electron microscopy and electron-backscattered diffraction suggested a uniform microstructure after PWNT compared to PWDT. For instance, the grain size range in heat-affected zone for T91 side and Super304H side was 5–80 μm and 10–140 μm, respectively, after PWDT, while it was respectively reduced to 5–35 μm and 10–60 μm after PWNT. Further, the PWDT heat treatment resulted in coarse Cr-carbides at grain boundaries (~ 671 nm), indicating sensitization on the Super304H side, whereas the PWNT heat treatment ensured small Cr-carbides (~ 504 nm), indicating that the sensitization phenomenon was delayed. Further, on the T91 side, the vulnerability of fine-grained heat-affected zone for type IV cracking has been identified and eliminated through PWNT treatment. The improved microstructure of PWNT against PWDT heat treatment correlated well with the enhanced mechanical properties, where 0.2% proof stress, tensile strength, % elongation and toughness for PWDT were 324 MPa, 649 MPa, 20%, and 109 MJ/m3, respectively, while after PWNT, these were improved to 384 MPa, 691 MPa, 22%, and 132 MJ/m3, respectively. For both treatments, failure was observed in the weld metal region due to coarse Nb/Ti intermetallic carbides.

Study of the influence of wire metals on dissimilar welds

The aim of this study is to investigate the effect wire metal on microstructure and mechanical properties of dissimilar welds between HSLA-X70 high strength steel alloy and 304L austenitic stainless steel produced by automatic tungsten arc welding (TIG). The weld joints were prepared using E304L, E316L, E2209L, and E7010 wire metal. The mechanical characteristics obtained from hardness, tensile and impact testing, were correlated to the optical and SEM microscopy, to establish a relationship between wire metal composition and the microstructures in different weld regions. It is concluded that E2209 wire metal lead to improve in the resilience characteristics and tenacity with a slight reduction in the ultimate tensile strength and hardness.

Microstructure and mechanical properties of dissimilar welds between 16Mn and 304L in underwater wet welding

ABSTRACTDissimilar joint between 304L austenitic stainless steel and low-alloy steel 16Mn was underwater wet welded using self-shielded nickel-based tubular wire. Microstructure, mechanical properties and corrosion behaviour of dissimilar welded joints were discussed. Ni-based weld metal was fully austenitic with well-developed columnar sub-grains. Type II boundary existed between Ni-based weld metal and ferritic base metal in underwater welds similar to that in air welds. Major alloying elements distributed non-uniformly across the austenitic weld metal/16Mn interface. Maximum hardness values in wet welding appeared in a coarse-grained heat-affected zone at the 16Mn side, which possessed very low impact toughness. Underwater Ni-based welded joints fractured at Ni-based weld metal under tensile test. Ni-based weld metal had favourable corrosion resistance similar to 304L base metal.

Tensile properties of dissimilar friction stir weld joints of Al-2024 and Al-7039 alloys

This manuscript deals with the dissimilar friction stir welding of 2024 and 7039 aluminum alloys, which are mainly used in aviation and automotive industry. A threaded truncated conical tool was used to carry out friction stir welding of dissimilar alloys. The weld joints were characterized by visual inspection, optical and scanning electron microscopy, energy dispersive spectrometry, x-ray diffraction and tensile tests. Weld joints exhibited mixed structure comprising of both the base materials and heterogeneously distributed Cu and Zn in the weld region. The weld strength efficiency was found higher than the elongation efficiency. The low weight percentage of Cu and Zn in weld nugget zone can be attributed to dissolution of strengthening precipitates in this zone. Softening due to dissolution resulted in reduction of mechanical properties of dissimilar welds. The results suggest that 2024 and 7039 dissimilar alloys are friction stir weldable with promising properties.

Investigations on the microstructure and mechanical properties of dissimilar welds of inconel 718 and sulphur rich martensitic stainless steel, AISI 416

Turbine blisk and shaft assembly in aero-engines make use of dissimilar joints of Inconel 718 and martensitic stainless steel, AISI 416. The joining of these 5 mm thick aerospace alloys carried out by adopting current pulsing in Gas Tungsten Arc Welding (GTAW) has been addressed. Two Nb free consumables namely ERNiCrMo-4, ERNiCu-7 and a duplex filler ER2553 were used to join these dissimilar combinations. The weldments were systematically characterized using optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). It is endorsed from the studies that the welds obtained from these fillers were free from deleterious Laves phase. Irrespective of fillers, the tensile failures were experienced at the base metal side of AISI 416. Room temperature Charpy V-notch impact test indicated that the weld joints employing ERNiCu-7 witnessed better impact toughness than other weldments. This study is highly in demand in aerospace industries and successfully addressed the choice of fillers in supressing the Laves phase.

A Comparative Study on the Effect of Electrode on Microstructure and Mechanical Properties of Dissimilar Welds of 2205 Austeno-Ferritic and 316L Austenitic Stainless Steel

A Comparative Study on the Effect of Electrode on Microstructure and Mechanical Properties of Dissimilar Welds of 2205 Austeno-Ferritic and 316L Austenitic Stainless Steel

Mechanical Properties of Dissimilar Welds between Stainless Steel and Mild Steel

Joining of stainless steel type 304 to mild steel was carried out using a gas tungsten arc welding (GTAW). Samples were welded using stainless steel welding electrode: (AWS: E308l-16) and mild steel welding electrode: (AWS: E6013). The mechanical properties of welded joint were investigated by tension test. It was observed that, the yield strength and tensile strength of welded samples using mild steel welding electrode were slightly lower than welded samples using stainless steel welding electrode. All welded samples fractured at mild steel base metal indicated that the regions of stainless steel base metal, fusion zone and heat affected zone are stronger than mild steel base metal.

Influence of Artificial Aging on Microstructure and Mechanical Properties of Dissimilar Welds between 310 Stainless Steel and INCONEL 657

This investigation is carried out to characterize welding of AISI 310 austenitic stainless steel (SS) to INCONEL 657 nickel-chromium superalloy. The welds were produced using four types of filler materials: the nickel-based corresponding to INCONEL 82, INCONEL A, INCONEL 617, and 310 austenitic SS. This article describes the effects of aging treatment on the joints. A comparative evaluation based on microstructural features and estimation of mechanical properties was performed. INCONEL A and INCONEL 82 exhibited the highest thermal stability and mechanical properties, while INCONEL 617 and 310 SS filler materials showed weak mechanical properties and thermal stability. It is therefore concluded that for the joints between INCONEL 657 and 310 SS, INCONEL A and INCONEL 82 filler materials offer the best compromises.