Dissimilar Metal Research Articles

Role of submerged friction stir welding in reducing intermetallic growth and enhancing microstructure in dissimilar Al-Ti joints

The integrity of dissimilar Al-Ti welds during conventional friction stir welding (CFSW) is compromised by excessive material mixing, leading to thick intermetallic layers. Underwater friction stir welding (UWFSW) mitigates these effects by inhibiting material mixing due to lower thermal conditions. Scanning electron microscopy revealed substantial Ti particles, appearing as blocks and strips, within the stir zone during CFSW. Static recrystallization, driven by exothermic reactions between Ti blocks and the Al matrix, resulted in over 93% recrystallized grains along stir zone, 10.7% higher than in UWFSW. In contrast, UWFSW resulted in a finer dispersion of Ti particles with reduced density due to lower frictional heat. The average grain size at the Ti interface of CFSW was 1.0 μm, compared to 2.6 μm in UWFSW. The inhomogeneous distribution of Ti particles in CFSW led to uneven dislocation distribution and increased stress concentrations, while finer Ti particles in UWFSW promoted a uniform grain structure, enhancing joint strength to 267 MPa, 13.4% higher than CFSW. Additionally, the γ-fibre and basal fibre texture in UWFSW increased joint ductility. The study highlights UWFSW’s effectiveness in joining dissimilar metals, offering significant advantages for industries such as aerospace and automotive.

Dissimilar unbeveled aluminum to steel butt joint achieved by laser-arc hybrid welding-brazing

In this study, unbeveled butt joints of 2 mm thick steel and aluminum plates were welded using a laser-arc hybrid process. The influence of welding speed and wire feed speed on joint weld formation, microstructures, and mechanical properties were investigated. The results indicate that using a laser-arc hybrid heat source enables good weld formation of steel/aluminum dissimilar metals without groove preparation, even under high welding speed conditions. The steel side interface formed Fe₂(Al,Si)₅ near the steel and Fe(Al,Si)₃ near the aluminum. As the welding heat input decreased, the thickness of the intermetallic compounds gradually reduced. With an increase in welding speed or wire feed speed, the tensile strength of the joint first increased and then decreased, reaching a maximum of 104.47 MPa. Cracks propagated rapidly along the intermetallic compound region, resulting in brittle fracture characteristics. The three-point bending test showed a maximum longitudinal bending angle of 53.82° and a maximum transverse bending angle of 36.54°.

Application of ANN Concepts for Prediction of Crack Growth and Remaining Life of Circumferentially Cracked Piping Components under Different Loading Scenarios

This paper presents the details of Artificial Neural Network (ANN) based models to predict crack depth and remaining life of circumferentially part-through cracked piping components used in the nuclear industry. Crack growth data from experimental studies on (i) straight pipes made up of SA 312 Type 304LN stainless steel having part-through circumferential notch under combined bending and torsion and (ii) dissimilar metal pipe weld joints having circumferential through-wall crack in the weld were used. The dissimilar metal pipe weld joint is made up of SA312 Type 304LN austenitic stainless steel and SA508 Gr. 3 Cl. 1 low alloy carbon steel and joined by Nickel-rich Inconel alloy weld. About 75% of the mixed experimental data has been used for development of model and the remaining data for validation. For the development of ANN model, (i) back propagation technique (ii) sigmoidal transfer functions and (iii) Levenberg-Marquardt algorithm are used. The maximum percentage difference observed between the predicted and the experimental results for crack depth and remaining life was 19.59% and 15.78% respectively. The efficiency of the developed model was verified using several statistical parameters. The developed models are useful for the structural integrity assessment of piping components under different loading scenarios.

Ultrasonic Welding Parameter Optimization for Electric Component Welding

Industrial requirements to establish metallic joints between dissimilar metals in the electric area. The ultrasonic welding process is an optimal process to joint thin sheets or foils. The goal of the research was to optimize the ultrasonic welding parameters to join thin nickel-coated copper sheets and aluminium sheets. It used a 0.5 mm thick high-purity copper (Cu-OF-R200) sheet coated with a 10 μm pure nickel layer and a 0.5 mm thick aluminium (1050A H24) sheet. The ultrasonic welding is made by a Branson Ultraweld L20 ultrasonic welder equipment. The mechanical properties and exacting geometrical tolerance of the joint were required. The welding parameter optimization is made empirically, with several welding tests. The optimal welding parameters were confirmed by non-destructive and destructive tests of the joints. The non-destructive tests were the visual inspection and geometrical measurements of the joint sizes. The destructive tests were tensile tests and macroscopic and microscopic tests. The completed test results confirmed the process applicability and the quality of the joint.

Magnetic pulse welding for dissimilar metals and corrosion studies at interface

Magnetic Pulse Welding (MPW) is an eco-friendly, solid-state welding method that utilizes high-velocity impacts. It operates without the necessity for fillers or flux and generates no harmful fumes. The process harnesses electromagnetic forces to weld two dissimilar job pieces by rapidly discharging current (∼100 µs) from a capacitor bank into a tool coil. This action produces a significant magnetic field (∼35 T) in the tool coil, which induces eddy currents in the job pieces, causing the outer piece to strike the inner piece at high velocities. Dissimilar metal joints such as Al-Cu, Cu-SS304, Al-SS304 and Ti-SS304 were successfully welded under these conditions using a 200 kJ MPW system. The resulting joints passed helium leak tests and exhibited a characteristic wavy morphology at the interface. Hardness measurements are conducted to investigate the mechanical properties of these joints, which provide valuable insights into the weldability and interface bond strength. Corrosion behaviour was evaluated, revealing bimetallic corrosion at the interface area. The welds were found to be flawless, instantaneous, and stronger than the base materials, confirming the potential of MPW for joining dissimilar metals with minimal corrosion rate of 0.441 mpy attained for the Ti-SS304 joint.

A Review on Joining of Dissimilar Metals with Highly Differential Thermomechanical Properties

A Review on Joining of Dissimilar Metals with Highly Differential Thermomechanical Properties

Analysis of Stress Corrosion Cracking Growth Rate in the Heat-Affected Zone of 316L Based on the Heterogeneity of the Mechanical Properties

The heterogeneity of the microstructure and mechanical properties of safe-end dissimilar metal welded joints (DMWJs) presents a challenge to the quantitative prediction of the stress corrosion cracking (SCC) growth rate directly from laboratory data. This study investigates the effect of the heterogeneity of the mechanical properties of the 316L-welded heat-affected zone (HAZ) in safe-end DWMJs on the SCC tip stress-strain field and the SCC growth rate. First, based on the analysis of microstructures in localized regions within the 316L-welded HAZ and the acquisition of material mechanical properties through microhardness testing, a user-defined material subroutine was developed to characterize the heterogeneous material properties within the 316L-welded HAZ. Then, using this finite element model with an inhomogeneous distribution of the mechanical properties of the material, the crack tip strain rates (CTSRs) at different locations within the 316L-welded HAZ were obtained. In conjunction with the FRI model, the SCC growth rates at various locations within the HAZ were determined. The results show that the closer to the 52Mw/316L fusion boundary within the 316L-welded HAZ, the greater the yield strength of the material and the higher the CTSR and predicted SCC growth rates at the characteristic distance.

Formation and strengthening mechanism of high entropy nugget for aluminum/steel resistance rivet welding

Resistance rivet welding (RRW) was a promising joining process for aluminum (Al) alloy and steel. The high entropy mixed nugget (HEMN) with the composition of Al0.8CoCrFe1.6Ni was obtained by introducing a high entropy alloy (HEA) rivet in RRW process. The high entropy played a significant role in facilitating the formation of solid solution. The HEMN microstructure exhibited a nanometer-sized weave-like structure caused by spinodal decomposition, comprising both BCC and B2 phases. The average hardness of the HEMN exceeded that of the Al/Steel mixed nugget, resulting in higher lap-shear strength and ductility. The analysis of strengthening mechanism demonstrated that the lattice misfit and order strengthening were the primary contributors. This study provided a novel strategy for joining dissimilar metal materials.

Evaluation of Tensile Strength of Dissimilar Metals SS 316-pure Zn Joining by Friction Welding Method

Welding of dissimilar metals has always been a challenge in industrial applications. In this study, the joining of SS 316 and 99.9% pure zinc by continuous drive friction welding has been carried out. The welding process is carried out with parameters such as rotation speed, friction pressure, forging pressure, and burn length being kept constant for all weld joint samples. This friction time is selected through the process parameter approach carried out on aluminium alloy material. The experimental results were analysed by tensile test and microstructure using a scanning electron microscope (SEM) to characterise the microstructure. Tensile test results from friction welding with variations in friction time from 30 to 80 seconds obtained a higher tensile strength of the joint in the 30 to 50 seconds friction time range. In this experiment, the maximum joint tensile strength is obtained at 53.93 MPa, and the maximum modulus elasticity of 128.60 GPa at 35 seconds of friction. Solid-state welding makes it possible to join SS 316 and pure zinc, which is difficult to join in conventional fusion welding methods.

Novel approach for in-line process monitoring during ultrasonic metal welding of dissimilar wire/terminal joints based on the thermoelectric effect

AbstractUltrasonic metal welding (USMW) is a manufacturing technique widely employed in the automotive and aerospace industries due to its efficiency in joining similar as well as dissimilar metals. Despite its prevalence, the lack of effective in-line process monitoring methods has resulted in high scrap rates, product recalls due to unrecognized scrap or financial losses due to pseudo-scrap, limiting its application in more sensitive industries. This paper presents a novel thermoelectric effect-based method for in-line process monitoring of USMW processes. This approach utilizes the thermoelectric properties, that manifest at the junctions of dissimilar metals during welding to accurately measure the temperature of the weld zone without the need of additional thermocouples, pyrometers or infrared cameras. An experimental setup was developed to validate the thermoelectric-based temperature measurement methodology. Key to this approach is the detection of thermoelectric voltage developed due to thermo diffusion when dissimilar materials are joined. The experiments showed a strong correlation between the thermoelectric voltage and the mechanical strength of the welds, suggesting that this parameter can effectively predict the quality of the weld. In the trials, a series of welded samples was created under controlled conditions to measure the generated thermoelectric voltage and correlate it with ultimate tensile strength tests. The data were analyzed using Spearman’s correlation coefficients to determine the correlation of the thermoelectric signals and joint strength. Results indicate that the thermoelectric voltage measurements correlate highly with the joint strength, with a Spearman’s correlation coefficient of over 0.94, thereby providing a promising predictive metric for assessing weld quality.

A Review On Multi objective Optimisation of Process Parameters in Shielded Metal Arc Welding For Joining Stainless Steel 3041 And Mild Steel 1018

Due to Mechanical properties of the welding metal and heat affected zone (HAZ) is quality of welding in this research work the review of Multi-objective optimization of welding process parameters for obtaining best weld strength with good mechanical properties of dissimilar metals like stainless steel 3041 and Mild steel 1018 is done. This process used for welding is shielded Metal Arc welding and dissimilar metal are stainless steel 3041 and mild steel 1018. Welding speed, depend on electric property like current Voltage electrode angle, feed rate, Arc length are taken as controlling variables. The weld strength (N/mm2) and Bead geometry variables and Heat Affected Zone are obtained by set of experiment, the possible best outcomes and best method has been chosen by this research. Keywords: HAZ, Multi objective optimization, Response surface Methodology, Shielded metal arc welding

A comparative study of friction stir welding and friction stir scribe technique for dissimilar metal joining

Abstract Friction stir welding (FSW) has emerged as a novel method for joining similar and dissimilar ferrous and non-ferrous materials. This solid-state welding process utilizes frictional heat generated between a tool shoulder and the base material. The stirring action facilitates the movement and consolidation of the material, resulting in localized fusion and the formation of a joint. This review examines their effectiveness in joining various material combinations, with particular focus on automotive and aerospace applications. FSW utilizes frictional heat and stirring action to create localized plasticity and material flow, while FSS incorporates a cutting feature to mechanically interlock dissimilar materials. The review paper shows comparison of various experimental investigations considering variables such as tool geometry, welding parameters, and material combinations. FSW has some significant parameters to enhance weld quality such as traverse speed, plunge depth, and tool design. These techniques show promising applications for multi-material integration, offering advantages over conventional fusion welding methods. Future research directions include expanding material combinations, developing automated systems, and exploring hybrid joining approaches.

Friction Stir-Based Techniques: An Overview

AbstractFriction stir-based techniques (FSTs), originating from friction stir welding (FSW), represent a solid-state processing method catering to the demands of various industrial sectors for lightweight components with exceptional properties. These techniques have gained much more attraction by providing an opportunity to tailor the microstructure and enhance the performance and quality of produced welds and surfaces. While significant attention has historically been directed towards the FSW process, this review delves into the working principles of FSTs, exploring their influence on mechanical properties and microstructural characteristics of various materials. Additionally, emphasis is placed on elucidating the advancement of hybrid FSW processes for both similar and dissimilar metal components, aimed at enhancing welding quality through meticulous control of grain textures, structures, precipitation, and phase transformations. Finally, the review identifies current knowledge gaps and suggests future research directions. This review paper synthesises academic literature sourced from the Web of Science (WoS) and Scopus databases, supplemented by additional sources such as books from the last 15 years.

Microstructure and mechanical properties of ultrasonically welded aluminum to Zn–Mg–Al coated and uncoated mild steels

The gaining popularity of aluminum alloys in the automotive industry demand the development of energy efficient joining methods of Al with other metals such as steel. Among such joining methods, ultrasonic welding is advantageous because it is cost effective and prevents metallurgical defects because of the low welding energy involved. This study evaluates the microstructural changes and mechanical properties of dissimilar ultrasonic welding of Al to Zn–Mg–Al-coated and uncoated mild steels. Various intermetallic compounds (IMCs), such as FeAl3, and Fe2Al5 with different thicknesses and morphologies were observed at the joint interfaces. The Al-to-Zn-Mg-Al-coated steel exhibited mechanical properties that are superior to those of Al-to-uncoated mild steel. The results are discussed in terms of microstructure evolution, joint characteristics, and interfacial reactions in the welds. This study contributes to the understanding of the mechanisms behind strong ultrasonic welding of dissimilar metals.

Dissimilar fabrication of the TC4/Ni60 bimetallic structure by laser melting deposition using a V/Cu transition bilayer

The bonding of Ti and Ni alloys to manufacture high-quality bimetallic structures represents an optimal integration strategy for fully leveraging their superior performance. However, the metallurgical bonding between TC4 and Ni60 dissimilar metals is extremely challenging due to the formation of TiNi, TiC and TiFe brittle intermetallic compounds and the differences in thermophysical properties. To address this issue, this paper presents a solution based on the compatibility of elemental components. A V/Cu transition bilayer was designed to achieve defect-free bonding between TC4 and Ni60 by laser melting deposition. The microstructure of the TC4/Ni60 bimetallic structure was analyzed by SEM, XRD and EBSD to evaluate its feasibility. The results indicate that the generation of brittle intermetallic compound phases was reduced to a certain extent when a V/Cu transition bilayer was employed, thus preventing cracking and peeling of the TC4 substrate and Ni60 cladding layer. Additionally, the mechanical properties of the bimetallic structure were evaluated through micro-shear tests and tensile tests. The micro-shear test results indicate that the weakest layer of the bimetallic structure is the Cu transition layer with a shear strength of 183.0 ± 108.8 MPa and an indentation rate of 8.25 ± 3.3 %. The room temperature tensile results demonstrate that the developed bimetallic structure fractured at the Cu/Ni60 interface, exhibiting a tensile strength of 286.3 ± 54.1 MPa and an elongation of 6.3 ± 0.5 %. The expected research can provide valuable references for improving the mechanical properties of TiNi dissimilar bimetallic structures produced by laser melting deposition.

Mathematical model for estimation of strength and weld bead geometry of dissimilar metal laser welds

Mathematical model for estimation of strength and weld bead geometry of dissimilar metal laser welds

Achieving metallurgical bonding in steel faceplate/aluminum foam sandwich via hot pressing and foaming processes: interfacial microstructure evolution and tensile behavior

This study introduces an innovative approach to fabricating aluminum foam sandwich with aluminized steel faceplates through metallurgical bonding. The process involves the use of foamable precursor, prepared via melt stirring, and subsequent hot pressing and foaming, offering a cost-effective and industrially feasible method for producing lightweight structural materials and connection of steel/aluminum dissimilar metals. This study focuses on exploring the changes in the microstructure of the bonding interface before and after foaming, and revealing the impact of these changes on the tensile results. Foaming experiment shows that foamable sandwiches have superior foaming ability, and the core layer density after foaming is between 0.283 and 0.591 g/cm ³. Microstructural characterization results demonstrate that, during the hot pressing process, fine equiaxed grains are observed on the iron side of the interface, indicating dynamic recrystallization occurred. The formation of a small amount of η-Al5Fe2 at the interface is a primary factor causing the deflection of the fracture path. Subsequently, during the foaming process, intermetallic compounds (IMCs) θ-Al13Fe4, τ5-Al7Fe2Si, and β-Al4.5FeSi formed sequentially, mainly determined by the diffusion reaction of silicon elements. The formation of these IMCs led to an increase in microhardness at the interface and a decrease in shear strength. Digital image correlation was utilized to examine strain distribution under tensile loading. The result indicates that the damage accumulation is characterized by the formation and expansion of strain bands, with failure manifested as the interconnection of these strain bands.

Optimization of TIG welding process parameters using Taguchi technique for the joining of dissimilar metals of AA5083 and AA7075

This research paper aims to optimize the TIG welding parameters to join dissimilar metals of AA5083 and AA7075 using the Taguchi technique. The TIG welding current and root gap of butt geometry configuration are considered input parameters, and welding characteristics such as tensile strength, 0.2% of yield strength, hardness, and impact energy are output responses. The base metals are joined according to the Taguchi L-09 design of experiments. The welded samples were inspected using the X-ray radiography method for internal defects. Tensile properties, hardness number, and impact energy of different welding coupons were evaluated by conducting the uni-axial testing, a Brinell hardness test, and an Izod impact test, respectively. A better weld strength of 224 MPa was observed at 210 A welding current, and the root gap of 1.5 mm was maintained. Better hardness and impact energy values were observed when the root gap of 1.5 mm and welding current of 220 A were maintained. The root gap is the primary factor influencing tensile strength enhancement, which accounts for 44.78% of the effect, followed by 40.5% welding current. Root gap is the parameter that affects the tensile properties, hardness number, and impact toughness the most. The findings of this paper suggest the optimal parameters for welding AA5083 and AA7075 dissimilar base metals, which are suitable for complex structures requiring both durability and resistance to harsh environments.

Analysis of fatigue fracture mechanism of laser spiral welding of dissimilar metals of 6082 high strength aluminum alloy and DP980 high strength dual phase steel

This paper investigates the relationship between weld quality, influencing factors, microstructure and mechanical properties of laser spiral dissimilarity welding of 6082 high-strength aluminum alloy and DP980 high-strength dual-phase steel, focusing on the fatigue properties and fracture mechanism of 6082-DP980 dissimilar metal welded joints. The research shows that intermetallic compound layers (IMCs) dominate the fatigue crack initiation stage and part of the crack extension stage, two fatigue crack initiation modes are obtained, one is the main crack initiation mode along the FeAl and FeAl2 interlayer, and the other is the secondary crack initiation mode along the Fe3Al and FeAl interlayer. In the crack propagation stage, due to the diffusion of Fe and Al elements generated by IMCs during the welding process, solid solution strengthening, intergranular strengthening and grain boundary strengthening, in the fatigue crack propagation stage formed a hardened zone, hindering the main crack to continue to expand along the IMCs, the main crack shifted to the expansion of the 6082 base material, thus extending the fatigue life.

Microstructure, Mechanical and Fractographic behaviour of the Diffusion Welded Joints of AA2219 and Ti-6Al-4V for Propellant Tank Applications

Diffusion welding is an advanced joining process that assures the feasibility of joining dissimilar metal alloys without producing metallurgical impurities at the joint interface. Two significant aerospace alloys, AA2219 and Ti-6Al-4V, are diffusion welded for the various holding times (30-120 minutes) by keeping the bonding temperature and pressure constant. The effect of holding time on the microstructure of the diffusion welded joints is evaluated using scanning electron microscopy (SEM), and the diffusion behaviour across the joint interface is ensued by the line scan energy dispersive spectroscopy (EDS). The obtained results show that the hardness across the joint interface is increased with increase in holding time. Furthermore, the maximum shear strength of 143.58 MPa is achieved for the joint formed at the holding time of 90 minutes and reduced thereafter. The formation of a thick intermetallic layer at a higher holding time strongly affects the shear strength. It is evident from the resulting fractured surfaces that the joints predominantly failed at the bonding interface, showcasing the brittle kind of failure. The X-ray diffraction (XRD) study on the fractured surfaces substantiates the formation of AlTi, Al2Ti and Al3Ti intermetallic compounds.