Steel Dissimilar Joints Research Articles

Enhancing mechanical properties of dissimilar steel A-TIG weld joint by in-situ induction post-heating

An approach is proposed to enhance the mechanical properties (ductility and impact toughness) of dissimilar martensitic steel-austenitic stainless steel joint by ‘A-TIG welding with induction post-heating (A-TIG(I) welding)’. The A-TIG(I) welding mitigates the martensite formation and promotes the ferrite formation within the weld zone (WZ) by retarding the cooling rate (from 9.83 °C/s to 0.8 °C/s). Microstructural transformations enabled in achieving the improved ductility (44.9 %) without significant loss of strength (665.75 MPa). Overmatched impact toughness (103 ± 2) J of WZ was also obtained.

Corrosion performance of super duplex stainless steel and pipeline steel dissimilar welded joints: a comprehensive investigation for marine structures

This study investigates the corrosion behavior of dissimilar gas tungsten arc (GTA) welded joints between super duplex stainless steel (sDSS 2507) and pipeline steel (X-70) using electrochemical and immersion corrosion tests. The GTA welds were fabricated using ER2594 and ER309L filler metals. The study examined the electrochemical characteristics and continuous corrosion behavior of samples extracted from various zones of the weldments in a 3.5 wt.% NaCl solution, employing electrochemical impedance spectroscopy, potentiodynamic polarization methods, and an immersion corrosion test. EIS and immersion investigations revealed pitting corrosion in the X-70 base metal/X-70 heat-affected zone, indicating inferior overall corrosion resistance due to galvanic coupling. The corrosion byproducts identified in complete immersion comprised α-FeOOH, γ-FeOOH, Fe3O4, and Fe2O3, whereas γ-FeOOH and Fe3O4 were predominant in dry/wet cyclic conditions. Corrosion escalated with dry/wet cycle conditions while maintaining a lower level in complete immersion. The corrosion mechanism involves three wet surface stages in dry/wet cycles and typical oxygen absorption during complete immersion. Proposed corrosion models highlight the influence of Cl−, O2, and rust layers.

Influence of arc energy on the microstructure and corrosion behavior of ER2209 duplex stainless steel deposited on Q345B low-alloy steel by GMAW

In order to eliminate the complex effects of thermal cycling and the thermal effects of the next pass on multi-layer multi-pass welding of low-alloy steel and duplex stainless steel, ER2209 welding wire was single-layer single-pass deposited on the surface of Q345B hot-rolled plate by gas metal arc welding (GMAW). The microstructure and corrosion resistance of welded joints were studied by different arc energies. The results showed that the arc energy had a significant impact on the “tongue-shaped” morphology and the width of heat affect zone in the welded joint, which in turn affected the corrosion performance of the welded joints. Due to the least distribution of “tongue-shaped” morphology and minimum width of heat affected zone in the welded joint with arc energy of 0.645kJ/mm, it owned the best corrosion resistance. The weld metals of the welded joints were composed of ferrite and austenite phases. The ferrite phases were distributed along grain boundaries and intergranular. As the heat input increases, the distribution of ferrite phase along grain boundaries gradually decreased. The corrosion products and corrosion morphology of the welded joint were also investigated and the corrosion mechanism was discussed in detail. The research results of this article provide a theoretical basis for improving the corrosion performance of multi-layer multi-pass welded joints of low-alloy and duplex stainless dissimilar steels.

Characterization and optimization of TIG welding parameters for AISI 304 and AISI 316 stainless steel dissimilar joints

This study explores the impact of tungsten inert gas (TIG) welding parameters on the mechanical properties and microstructure of dissimilar welds between AISI 304 and AISI 316 austenitic stainless steels. Given the growing industrial demand for these materials, the research focuses on optimizing welding current, shielding gas flow rate, and voltage to enhance tensile strength, hardness, and impact toughness. Using the L9 orthogonal array based on Taguchi’s methodology, the experiments revealed that Relatively highs currents and voltages significantly improved the ultimate tensile strength (up to 673.67 MPa) and impact energy absorption (up to 36.5 J). Microstructural analysis indicated refined grain structures in the heat-affected zones, with pronounced grain growth in AISI 316 due to its thermal sensitivity. The micro-hardness analysis revealed that the highest hardness occurred in the HAZ of AISI 304, with samples 5 and 6 exhibiting the optimal hardness profile, reflecting the most favorable welding parameters. The study concludes that a current range of 80-90 A and a voltage range of 10-11 V and a shielding gas flow rate of 12-16 L/min provide optimal welding conditions, offering robust guidelines for industrial applications requiring high-performance dissimilar welds.

Expulsion prevention in resistance spot welding of dissimilar joints with ultra-high strength steel: An analysis of the mechanism and effect of preheating current

The widespread adoption of ultra-high strength steels, due to their high bulk resistivity, intensifies expulsion issues in resistance spot welding (RSW), deteriorating both the spot weld and surface quality. This study presents a novel approach to prevent expulsion by employing a preheating current. Through characteristic analysis of joint formation under critical welding current, the importance of plastic material encapsulation around the weld nugget (plastic shell) at high temperatures in preventing expulsion is highlighted. To evaluate the effect of preheating on the plastic shell and understand its mechanism in expulsion prevention, a two-dimensional welding simulation model for dissimilar ultra-high strength steel joints was established. The results showed that optimal preheating enhances the thickness of the plastic shell, improving its ability to encapsulate the weld nugget during the primary welding phase, thereby diminishing expulsion risks. Experimental validation confirmed that by employing the optimal preheating current, the maximum nugget diameter was enhanced to 9.42 mm, marking an increase of 13.4 % and extending the weldable current range by 27.5 %. Under quasi-static cross-tensile loading, joints with preheating demonstrated a 7.9 % enhancement in maximum load-bearing capacity compared to joints without preheating, showing a reproducible and complete pull-out failure mode within the heat-affected zone. This study offers a prevention method based on underlying mechanisms, providing a new perspective for future research on welding parameter optimization with the aim of expulsion prevention.

Role of buttering layer composition on microstructural heterogeneity and mechanical properties of Alloy 617 and P92 steel dissimilar welded joints for future Indian AUSC program

Restrictive operating conditions (even exceeding 700 °C) of materials in advanced ultra super critical (AUSC) power plants and the need to minimize manufacturing and maintenance costs require the production of dissimilar metal welded joints (DMW). Significant differences in the physical and chemical properties of welded materials lead to phenomena that reduce the weldability of the metals used and force the search for solutions that limit unfavorable phenomena, e.g., the use of buttering layers. The study presents a comparison of two types of joints with Alloy 617 (UNS N06617) and ferritic P92 (UNS K92460) steel made using Inconel 82 (ENiCrFe-3) and Inconel 617 (ERNiCrCoMo-1) alloys buttering layer and the corresponding chemical composition of filler metals. All areas of the joints made with the gas tungsten arc welding process were subjected to structural investigations (optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) and mechanical tests (microhardness, room and high temperature tensile, and toughness testing). Despite the more complicated welding procedure, sound welded joints were obtained with favorable properties resulting, inter alia, from the reduced thickness of the martensite layer in HAZ of P92 steel and the limited diffusion of alloy components compared to welded joints without the buttering layer. This also resulted in a reduction of the maximum hardness (especially in the case of Inconel 82 buttering—by 15–30 HV0.5 in comparison with Inconel 617 buttering) and an increase in strength while limiting the decrease in plasticity (even 663 MPa tensile strength and 21% of elongation for Inconel 617 buttered joint). Moreover, improved high-temperature performance (approximately 70–100 MPa) of the welded joint following the application of the buttering layer was confirmed. The presented results allow for drawing general conclusions that both proposed welding procedures can be recommended for use in the working conditions occurring at AUSC.

Role of Cr addition in Ni-based interlayer on strengthening titanium and steel dissimilar bimetallic structures enabled by directed energy deposition with laser beam

For searching alternative strategies to improve reliability of titanium and steel dissimilar bimetallic joints manufactured by directed energy deposition with laser beam (DED-LB), pure titanium was considered as cladding deposited on carbon steel substrate with Ni-based alloy interlayers in this work. Effect of different interlayer modification methods on the microstructure evolution and mechanical properties of joints was analyzed systematically. The distribution of intermetallic compounds (IMCs) such as β-Ti, Ti2Ni, TiNiFe0.2, Ti2Ni3Si and TiB2 in joints was revealed. The results showed that original deposition cracks caused by residual stress during processing could be alleviated by substrate preheating treatment while suppressed by the modified interlayer with Cr completely. Notably, additional Cr could reduce reaction activity between Ti and Ni atoms by raising laser molten pool liquidus, leading to fewer IMCs in joints. As a result, both bonding strength and toughness of joints were remarkably improved. The findings emphasize more significance of optimizing Ni-based interlayer composition with Cr than preheating method to improve the mechanical performance of DED-LB 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

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

Stable production of dissimilar steel joints in construction machinery by narrow gap oscillating laser welding

Narrow gap oscillating laser welding with filler wire is a promising technique for joining high-strength steels in construction machinery. In order to investigate the influence of beam oscillation on the surface morphology and microstructure of weld joints of two types of commonly-used high-strength steels, a comparative study between oscillation welding and non-oscillation welding was conducted. High-speed photography technique was employed to reveal the microstructure and mechanical properties of the dissimilar joints. The results showed that laser beam oscillation produces two effects: one was to enlarge the heated surface of molten pool, while the other was to stir the liquid metal in molten pool periodically. Under the first effect, the fusion between sidewall and weld bead layers was promoted, while under the latter, coarse columnar grains ceased to appear, but finer grains were formed. The weld joints between Q355 and 35 steels exhibited excellent tensile impact bending performance, which was attributed to the grain refinement effect. The results also demonstrated that the oscillation welding with a contact angle less than 50° could avoid lack of fusion in multi-pass wire-filling laser welding. The influence of the oscillation welding process on the quality of welding was further discussed.

Investigating the microstructure and mechanical properties in furnace brazing Ti–6Al–4V to 17-4 PH stainless steel dissimilar joint with BNi-2 filler metal

Due to the distinct physical and metallurgical characteristics of titanium and steel, the welding of these two materials poses challenges and holds significant importance. This study investigates the impact of brazing time and temperature on the microstructure and mechanical properties of dissimilar brazing between 17-4 PH stainless steel and Ti–6Al–4V using BNi-2 as a filler metal, focusing on the formation of brittle compounds like FeTi and Fe2Ti during the brazing process. The joint between these materials is commonly utilized in various industrial applications. The assessment involved the use of optical microscope, scanning electron microscope, shear – tensile test, microhardness test, and wettability measurement. Brazing of the base metals was conducted at temperatures of 1050/1100 °C for durations of 15 and 30 min to determine the optimal temperature and time combination. The results indicated that the best joint properties were achieved at 110 °C for 15 min, with an average shear strength of 38.46 MPa. Contact angle measurements revealed that BNi-2 exhibited superior wettability on 17-4 PH compared to Ti–6Al–4V. Furthermore, increasing the temperature from 1050 to 1100 °C led to a reduction in contact angle from 9.98 to 8.83° for 17-4 PH, and from 16.51 to 10.12° for Ti–6Al–4V indicating an improvement in wettability.

Optimization of mechanical and surface properties of friction stir welded dissimilar joint of 2507 SDSS and 317L ASS by controlling process parameters

Stainless steel welding has been widely used in industrial manufacturing, and friction stir welding has been recognized to reduce production costs significantly. To fully utilize the different properties of 2507 super duplex stainless steel (SDSS) and 317L austenitic stainless steel (ASS), the mechanical and surface properties of 2507 SDSS and 317L ASS dissimilar stainless steel joints were improved using the friction stir welding (FSW) method. The influence of rotation speed on the microstructural characteristics, mechanical properties, and corrosion behavior of the weld joints was investigated by welding at a constant speed of 20 mm/min within the range of 300–600 rpm. Specifically, at 400 rpm, a welded joint with optimal performance was obtained. When the rotation speed is 400 rpm, the yield strength (YS) and ultimate tensile strength (UTS) of the welding joint are 493 and 692 MPa, respectively, and the elongation (EL) is 32 %. The tensile strength is higher than 317L ASS but lower than 2507 SDSS, the EL is lower than those of 317L ASS and 2507 SDSS, and the friction coefficient of the welded joint is 0.93, which is between 317L ASS and 2507 SDSS. Notably, the refinement of grains in the stirred zone significantly improved the corrosion resistance of the welded joint, considerably exceeding that of the 317L ASS but still lower than the 2507 SDSS. This work can provide a process reference for studying the mechanical and corrosion properties of dissimilar stainless steel FSW.

Evaluation of dissimilar TIG welded joints of novel high strength low alloy steel for automotive applications: Experiment and numerical comparative approach

Modern automotive, aerospace, and manufacturing sectors use tungsten inert gas (TIG) welding widely as a critical procedure due to the weld's quality and joint efficiency. In this study, mechanical characterization of TIG-welded joints of high strength low alloy (HSLA) steel with two different grades (S1 and S2) was performed experimentally and mechanical properties were calculated in terms of hardness profile along the weldment and load-displacement curves. True stress-strain curves of base metal, heat-affected zone, and melted zones were used for calibration of the 8-node solid numerical model. The highest hardness value of 386 HV was obtained in the melted zone whereas a softening zone was observed in the heat-affected zone (HAZ) of S2 where the Vicker's microhardness value was 270 HV. During the comparison of simulation results with experimental data, it was found that the overall error was less than 5% which reflects a good accuracy of material models used for numerical modeling. A higher ultimate tensile strength was found in similar S1-S1 steel joints as compared to similar S2-S2 and dissimilar S1-S2 steel joints. Furthermore, the results of simulations revealed that the maximum von Mises stress (1050 MPa) concentrations were found in the HAZ of a similar S1-S1 welded joint, whereas the minimum von Mises stresses (880 MPa) in S2-S2 welded joint, and intermediate von Mises stresses (1010 MPa) on the side of S1 HAZ in S1-S2 dissimilar welded joint. The results of simulations and experimental study of TIG welding joints show good agreement with reasonable accuracy.

Tensile efficiency and fatigue life of similar and dissimilar carbon steel joints subjected to rotary friction welding

Rotary friction welding (RFW) is a solid-state welding method that can address the melting point limitation of other welding types; however, the welded area remains at risk of failure due to fatigue during operation. Fatigue failure is difficult to detect and predict, making it a critical failure mode in engineering. Although many fatigue life prediction methods are available, they do not consider the impact of RFW parameters (such as pressure, speed, and friction time) on fatigue strength. Owing to their good mechanical properties and commercial viability, carbon steel of grades C35 and C45 is commonly applied to manufacture main parts in the automotive industry. This study centers on employing RFW to join C35 and C45, representing the first-ever instance of using this technique to weld them together. The primary goal of RFW for C35 and C45 is to construct optimum parts that meet specific design requirements and have a long fatigue life. Findings showed C45–C45 joints (77 %) were more tensile-efficient than C35–C35 joints (73 %). Dissimilar C35–C45 joints reached 60 % of C45 base metal and 76 % of C35 base metal in terms of tensile efficiency. RFW welds had lower tensile strength than their base metals. Optimal results came at 35 MPa friction pressure and 8–12 s friction time for both similar and dissimilar RFW joints using the Coffin–Manson method, dissimilar C33–C45 joint fatigue life improved by over 85 %, aligning C35 and C45 engineering aspects. SEM microstructure analysis showed two regions: non-deformed (NDZ) and plastically deformed (PDZ), with broader PDZ indicating better tensile strength. These findings enhance RFW's efficiency, promoting automotive part longevity and safety.

Parametric investigation into the mechanical characteristics of dissimilar steel joints produced using SMHH-based joining technology

Selective microwave hybrid heating (SMHH)-based joining technology was utilized to fabricate dissimilar joints between SS2205 and SS304. The joining process involved exposing the materials to a 2.45 GHz frequency and 900 W of power for 720 s under atmospheric conditions, with SS304 powder used as the filler material. SMHH principles were employed to melt and fuse the filler powder with the interfaces of the joining specimens. To assess the joint properties, various characterizations were conducted, including X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), microhardness and tensile testing. XRD revealed the presence of carbides and intermetallics in the joint region. SEM revealed that the complete melting of powdered particles with the joining interface resulted in good metallurgical bonding between the joining specimens. The Vicker’s microhardness measured in the joint region was determined to be 515.2 HV, indicating a substantial increase as compared to the microhardness value of the joining specimens. The average measured ultimate tensile strength of dissimilar joints was 584.15 MPa, with an elongation of 20.27%. The SMHH-induced dissimilar welds between SS2205 and SS304 demonstrated promising microstructural and mechanical properties, indicating the effectiveness of this joining method in industrial applications.

Mechanical properties of MAG butt welded dissimilar structural steel joints with varying strength from grade S355 up to S960

AbstractMixed connections made of normal-strength and high-strength structural steels allow for optimized material usage and production effort in applications where, as a result of different mechanical effects on materials of the same type, it would otherwise be necessary to adjust the plate thickness. Reduced material consumption and smaller weld geometries can thus generate ecological and economic advantages. When welding high-strength structural steels, however, significant softening can occur in the heat-affected zone, which can influence the load-carrying behavior of the overall joint. Since there are currently no appropriate standards for butt welds made of steels with different strengths up to S960, a separate design concept is required. In this paper, the weldability and load-carrying capacity of multilayer MAG welded butt joints designed as mixed connections of a normal-strength structural steel S355 and a high-strength structural steel in the range S690 to S960 are investigated. Extensive experimental investigations are carried out, in which other influencing variables such as the filler metal used, the heat input, the plate thickness, and the weld geometry are varied in order to identify their effects on the load-carrying capacity of the welded joints. Among other things, the results form the basis for an empirically based design model for mixed connections.

Joining mechanism evolution of fusion welded TC4 titanium alloy/304 stainless steel dissimilar joint by GTAW

Gas tungsten arc welding with a pure Cu filler wire was carried out to join the TC4 titanium alloy and 304 stainless steel. Filling pure Cu filler wire assisted with regulating welding current could effectively restrain the concentrated generation of Ti–Fe brittle intermetallic compounds. Three joining modes exist in the fusion welding titanium alloy and stainless steel. In the partial fusion welding mode, the TiCu phase decreased and the fine granular τ2 phase formed in the Ti/Cu interfacial zone, simultaneously, the molten zone consisted of a Cu solid solution and α-(Fe, Cr) phase formed at the Cu/Fe interface, resulting in mechanical interlocking effect and consequent high tensile strength of 363 MPa. Increasing the welding current would lead to the alloying of Ti x Cu y phases, and then enhance the Ti/Cu interface.

Interface and microstructural characteristics of titanium and 304 stainless steel dissimilar joints by upset butt welding using a gleeble thermo mechanical simulator

This work discusses joining dissimilar material combinations of commercial pure titanium and 304 stainless steel utilizing an upset butt welding process. The process involves rapid heating to a temperature of 1150 °C at a heating rate of 200 °C/s with simultaneous application of pressure at a level of 1.5 MPa to achieve fusion. Then, the joints are post-heated to 850 °C during the soaking period for 90 min to relieve the welding residual stresses and achieve good bond strength. The upset welding experiments are conducted with the help of a Gleeble thermomechanical simulator. This process does not require the conventional severe metallographic preparation generally used for the typical diffusion bonding process. The weld joint achieves an ultimate tensile strength of 274 MPa, approximately 60% of the strength of commercial pure titanium. Moreover, intermetallic compounds occurred at the interfaces, which were attributed to significant changes in the microhardness of the Ti/SS alloy.

Interfacial reactions and joint performances of high-power ultrasonic welding of aluminum to steel

Aluminum and steel dissimilar sound joints were fabricated using a 4.0 kW high-power ultrasonic welder. The microstructure and mechanical properties of the joint resulting from high-power ultrasonic welding were investigated. To further understand the formation mechanism of the joint, macro and micro plastic deformation were also examined using the finite element method. As the welding duration increased to 0.4 s, the conversion of electrical power to heat flow at the interface also increased, with approximately 56% of the electrical power being transformed into the heat flow of the welding interface. The material flowed from the center of the welding interface and accumulated at the edge, resulting in a welding area measuring 9 mm × 7 mm, significantly larger than the sonotrode tip area. The plastic strain in the welding zone reached 3.7, with the aluminum side exhibiting higher plastic strain than the steel side, facilitating Fe atom diffusion towards aluminum. The intermetallic compound (IMC) primarily consisted of FeAl3 and Fe2Al5. The joint strength increased significantly as the thickness of the IMC increased. However, when the IMC thickness exceeded 1.7 μm, the joint strength decreased. Through interfacial metallurgical reactions and intense mechanical interlock, joints with a lap-shear strength of 62.7 MPa were achieved. The fracture mode of the joint was a ductile-brittle hybrid fracture.

Weld formation, microstructure and mechanical properties of magnesium alloy and Al-Si-coated steel dissimilar lap joints fabricated by the CMT weld-brazing process

Magnesium alloy and Al-Si-coated steel dissimilar lap joints were joined using the CMT welding process. The weld formation, microstructure and mechanical properties of Mg/steel CMT weld-brazing joints were investigated. The wetting and spreading behaviour of the molten magnesium alloy filler material on the steel substrate were evidently improved owing to the presence of the Al-Si coating. The Fe-Al intermetallic reaction layer formed at the interface and enhanced metallurgical bonding between the magnesium alloy and steel. The effects of the Al-Si coating and welding heat input on interface layer characteristics were particularly assessed. When the heat input was 178.1 J/mm, the tensile shear strength of the Mg/steel welded joints reached 359.3 N/mm. The fracture modes and failure mechanism for tensile shear specimens were analysed and discussed in detail.

Influence of the base metal grain size and heat input on decarburization in single pass SAW and multi pass SMAW welded joints of dissimilar ferritic steels

This paper aims to assess a separate influence of heat input and base metal grain size on microstructural evolution in the weld adjacent zone of bainitic steels with 1.5…2.0% Cr, welded or overlayed with consumables with 9% Cr after post-weld heat treatment.Analysis of the width of decarburised layer on microphotographs of welded or overlayed specimens after tempering at 750C. Specimens were made by using different welding approaches: single-pass welding, multi-pass welding and overlaying.It is shown that with an increase of the heat input energy, the width of the resulting decarbonised layer decreases linearly; the increase of the base metal grain size leads to a decrease in the layer width after tempering at 750C. The microhardness testing showed the average hardness in the decarburised layer of 15Kh2M2FBS steel was 161 HV0.1 (minimum – 154 HV0.1), while the average hardness in the rest of the heat-affected zone was 192 HV0.1.Future research may include comparing the creep rupture strength of the weldments made with different welding parameters or base metal grain size to assess the influence of these factors on creep rupture strength.Results permit to achieve minimisation of the rate of carbon diffusion in the weld-adjacent area of the heat-affected zone by means of variation of welded parameters and base metal grain size.An influence of high-diffusivity paths (grain boundaries) on carbon diffusion in the heat-affected zone of dissimilar weldments was confirmed experimentally; the correlation between base metal grain size/welding parameters and the rate of the diffusion during high-temperature exposure was found.