Dissimilar Metal Joining Research Articles

Dissimilar metal joining of aluminum to steel by hybrid process of adhesive bonding and projection welding using a novel insert element

Abstract Multi-material design offers cost-efficient lightweight solutions for automotive body-in-white production. It can be realized by joining ultra-high strength steels with aluminum alloys, using adhesive bonding, combined with another commonly used joining process. For these applications, processes like riveting, clinching, resistance spot welding have been pushed to their technological limits and a further technological development is needed. The present research describes a new joining technology based on resistance welding process for joining aluminum-silicon coated hot stamped ultra-high strength steel with aluminum. The technology consists of a two-stage projection welding process with an additional insert element. Its implementation allows joining aluminum and steel sheets using extremely short welding time with high energy concentration in combination with adhesive bonding. Due to low heat input in the welding process, the adhesive around the insert element is damaged significantly less, compared to classic resistance spot welding. Depending on insert element size and orientation, short flanges can be joined, offering potential for further weight reduction of the car body. The elements are easily applicable under different production constraints. One of possible applications of the investigated joining process is welding a thin outer aluminum sheet on a B-pillar. Welds were made using insert elements – cylinders of Cu- and Fe-based wires with diameter of 1.6 mm and length of 10 mm employing a medium frequency direct current resistance welding machine. Both tested materials can be successfully used and the weld current ranges are sufficient for industrial application with and without the use of adhesive. Mechanical properties of joints, evaluated using tensile-shear tests, are comparable with those of the existing mechanical joining methods used in automobile manufacture.

Applications and challenges of arc welding methods in dissimilar metal joining

Dissimilar metal welding is a significant metal joining process with an extensive application in industrial domain. The quality of the welded joint is of critical importance in these applications and quite an issue since the base metals are different primarily due to different physical, chemical and mechanical characteristics. In this paper, the challenges encountered in dissimilar metal joining are enlisted with a brief discussion on the corresponding causes. As discussed in the literature, several methods exist to form dissimilar joints. However, arc-based fusion methods are prominently used. Therefore, an overview of these methods is presented along with the applications in which these methods have been used. The study provides a brief account of the materials that have been successfully joined using these methods and the influence of significant parameters including filler materials on the effectiveness of dissimilar joining.

Influence of lap sequence on the Al/Steel FSKSW weld quality

The joining of dissimilar metals of 5A02 aluminum alloy and DP600 galvanized steel was carried out by keyhole-free FSSW technique (FSKSW). The effect of lap sequences on the microstructure and mechanical properties of welded joints was also investigated. It was found that all keyholes of both stacking sequences were filled, and the steel on top of Al alloy could be stirred more thoroughly than that vice versa The microstructure of WNZ contained fine equiaxed grains, and TMAZ formed fully developed plastic flow, while HAZ had coarse grains. The temperature of two stacking sequences was similar during the welding process. Still, the axial force of the joints of steel on aluminum alloy was higher than that of aluminum alloy on steel. Similarly, the joint strength of the steel on aluminum alloy was also higher than that of aluminum alloy on steel. It was necessary to place the steel plates on the aluminum alloy sheets for metal plasticity and heat distribution.

The Optimum Process Parameter of Dissimilar Metal AA6061 – AISI304 Continuous Drive Friction Welding

This article explains the use of the response surface method to produce the optimum tensile strength for the joining of dissimilar metals with the continuous drive friction welding method. The joining of dissimilar metals is one of the biggest challenges in providing industrial applications. Continuous drive friction welding has been extensively used as one of the important solid-state welding processes. In this study, the optimization of the friction welding process parameters is established to achieve the maximum tensile strength in AA6061 and AISI304 dissimilar joints via the response surface methodology. The effect of continuous drive friction welding parameters, which are friction pressure, friction time, upset pressure, and upset time, are investigated using response surface analysis. The design matrix factors are set as 27 experiments based on Box-Behnken. The 3D surface and the contour is plotted for this model to accomplish the tensile strength optimization. The optimization model of the tensile strength was verified by conducting experiments on the optimum values of the parameters based on the experimental data results. It can be denoted that the optimum process parameters settings were friction pressure = 25 MPa, friction time = 6 seconds, upset pressure = 140 MPa, and upset time = 8 seconds, which would result in a maximum tensile strength of 228.57 MPa.

Research on Friction Stir Spot Welding Brazing Process and Properties of Dissimilar Metals DP590 and 6061

Friction stir welding (FSW) is the most popular and efficient method for solid‐state joining of similar or dissimilar metals and alloys. This technology is mostly applied in aerospace, rail, automotive, and marine industries. In order to reduce the weight of special auto parts, friction stir spot welding (FSSW) was proposed by some researchers for the connection of steel‐aluminium dissimilar metals. However, the steel‐aluminium joints welded by FSSW are prone to brittle fracture and have lower shear load although they have high mechanical connection strength. The friction stir spot welding brazing process integrates the brazing effects with the friction welding effects by the addition of solder. A study of FSSW of DP590 and 6061 with the filler metal added was carried out in this paper. The orthogonal test was performed to optimize the process parameters in order to achieve the best shear load of the joint. The shear strength of the joint was studied by the shear test. The fracture morphology was investigated by optical microscopy (OM), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). The results showed that the shear load of the joint could reach 13.239 kN when the rotating speed, depth, and residence time of the mixing head were 1000 r/min, 0.2 mm, and 90 s, respectively. The aluminium‐zinc solder added could well wet the interface between aluminium and steel and promote the metallurgical bonding, thereby improving the shear load of the joint. The temperature field of DP590/6061 FSSW process was simulated by ANSYS software to verify the rationality of the optimal process parameters. The simulation results were confirmed to be basically consistent with the data measured by the thermocouple.

Investigation of TIG welding parameters to improve strength

Various welding process are present, among the various welding process, Tungsten inert gas (TIG) welding plays a major role in the welding of mild steel or thin sections of non-ferrous metals such as copper alloys, aluminum alloys, magnesium and stainless steel. Many advantages obtain in TIG welding to joining of dissimilar metals like slag avoidance, minimise heat affected zone etc. Since input parameters play a major role in determining the quality of a welded specimen. A plan of experiments based on L9 orthogonal array has been used to design of experiment, acquire the data and to maximize tensile strength of variation in welding parameters. Finally the tests have been carried out to evaluate the best process parameters for given aluminum alloy with the experimental values confirm its effectiveness by SEM in the analysis of strength.

PENGARUH FILLER PADA PENGELASAN TIG BAJA KARBON DAN STAINLESS STEEL 316L TERHADAP SIFAT MEKANIK

In the manufacturing industry, the integration of different types of material is needed. The dissimilar metal welding of two different material were required suitable filler types. The often combination of material was done is welding between steel and stainless steel. TIG (Tungsten Inert Gas) welding process used feed electrode an electric arc. The gas around welding area has been protected the molten metal with outside air. This study aimed to determine the effect of selecting a suitable filler on the joining dissimilar metal beetwen SS316L and low carbon steel with the TIG welding method. The mechanical characteristics of ER316L and ER70S filler variations were testing by Tensile strength and microhardness vickers. The highest tensile strength and hardness value were found in the specimen welded by ER70S filler at 410 MPa and 398,1 HVN (Hardness Vickers Number). According to the study results, the ER70S filler is more suitable beetwen welding on the stainless steel and low carbon steel.

Microstructure and Strength of Ultrasonic Plus Resistance Spot Welded Aluminum Alloy to Coated Press Hardened Boron Steel

Press-hardened boron steels with ultrahigh strength (above 1500 MPa) are widely used in crash-sensitive safety components in automobiles. Joining such steels to aluminum alloys is challenging due to various factors including the steel’s tenacious Al-Si coating. A novel application of ultrasonic plus resistance spot welding was developed for such dissimilar metal joining. The nugget formation and the interface microstructure especially intermetallics formed were correlated to the joint strength, ductility and failure behavior.

Effect of laser beam models on laser welding–brazing Al to steel

Joining dissimilar metals Al to steel in butt configuration was successfully realized by laser welding–brazing process with different laser beam models (single laser beam, cross and in–line dual laser beams). Undercut occurred at the joint produced by single laser beam and satisfactory weld formations were obtained in the joints produced by cross and in–line dual laser beams. Dual laser beam was beneficial for the reduction of interfacial intermetallic compound (IMC) thickness and homogenization of interfacial IMC morphology. Numerical models were developed to calculate the thermal cycles along brazing interface. Calculation of interfacial thermal cycles revealed that lowest peak temperatures (1028 °C, 1036 °C and 990 °C respectively for top, middle and bottom regions), shortest time of interaction at high temperature (2.2 S) and smallest temperature gradients (1036–990 °C = 46 °C) were all obtained in the joint produced by cross dual laser beam and these all made contribution to its thinnest and most homogeneous interfacial IMC. Joint with the highest tensile strength was produced when the cross dual laser beam was adopted due to its satisfactory weld formation and most homogeneous of τ5.

Dissimilar metal joining of aluminium to zinc-coated steel by ultrasonic plus resistance spot welding – microstructure and mechanical properties

Vehicle body structures are increasingly utilising multi-materials designs with advanced high strength steels (AHSS) and aluminium alloys. A robust process for joining aluminium alloys to AHSS based on resistance spot welding (RSW) is essential to widespread application of such bi-metallic structures in fuel-efficient vehicles. In this study, ultrasonic plus RSW was applied to join AA6022 to Zn-coated dual-phase steel DP980. During solid-state ultrasonic spot welding, an interface structure comprising multilayer, Al–Zn and Zn–Fe intermetallics formed due to alloying of aluminium with steel coating. Such structure was subsequently melted into the aluminium nugget, and new Al–Fe intermetallics formed during RSW. Ultrasonic plus resistance spot-welded joints had superior fracture energy than direct resistance spot-welded joints.

Galvanic Corrosion of Automotive Mixed Metal Substrates: Fundamental Understanding

Dissimilar metal joining is of increasing interest in many structural applications due to its potential to enable light weighting. Light-weight substrates such as aluminum alloys, magnesium alloys and carbon-fiber reinforced polymer (CFRP) are increasingly used in place of conventional steels due to their high strength-to-weight ratios. Two of the main challenges associated with the increased usage of mixed metal systems are galvanic corrosion and challenges with classical joining methods. 1,2. Most joining methods such as riveting, mechanical fasteners, and welding, results in electrical connection between the joined metals, which poses galvanic corrosion issues. Even galvanic isolation approaches such as the use of adhesives can cause galvanic corrosion problems due to the complexity of mixed metal assemblies. In galvanic coupling scenarios, the less noble material experiences severe corrosion and more noble material is protected. It is important to build a fundamental understanding of this phenomenon relative to the metallurgy and electrochemistry of the substrates, as well as the coupling method, to provide effective corrosion mitigation solutions. Electrochemical test techniques such as zero resistance ammeter measurements, open circuit potential measurements, and potentiodynamic polarization were utilized to understand effect of substrate type and solution pH on galvanic corrosion. In addition to the substrate effect, the effect of fastener type on galvanic corrosion between substrate and fasteners was also investigated for selected systems. The influence of joining methods such as self-piercing rivets, adhesives, and mechanical fasteners on galvanic corrosion was also studied. Galvanic and self-coupled coupons were exposed to standard laboratory accelerated life cycle test methods. Wedging by corrosion products, scribe creep, and corrosion volume loss were each characterized to quantify the extent of galvanic corrosion after environmental testing. Preliminary results indicated that galvanic coupling enhanced the wedging of substrate by corrosion products when aluminum alloy 6111-T4 (AA 6111-T4) is coupled with cold rolled steel (CRS). In addition, the pitting corrosion of AA 6111-T4 increased when it is coupled with CRS (Figure 1). Although hot dip galvanized (HDG) based galvanic coupons showed no significant wedging by corrosion products, galvanic coupling of CRS with HDG aggravate the scribe creep of HDG. Galvanic isolation methods such as coating before joining or utilizing adhesives significantly reduced galvanic corrosion in the model mixed-material systems. Figure 1. Average pit depth of AA 6111-T4 substrate coupled with different mixed-metal substrates after various exposure times in neutral and acidic cyclic corrosion tests (CCT). Acknowledgements: Research was sponsored by the Army Research Laboratory, the Tank Automotive Research Design Engineering Center, and Drexel University under Cooperative Agreement W911NF-13-2-0046 and related sub awards.

Microstructural Aspects of the Zircaloy-4/SS-304L Interface Obtained by Diffusion Bonding Technique

A dissimilar metal joining method based on diffusion bonding was developed to join 304L stainless steel (SS) and Zr alloy (Zy-4). This was done at 820°C and 950°C under argon and dynamic pressure for 45 minutes.The metallurgical structure of the interface and the evolution of its texture during the treatment were studied by evaluating the distribution of the constituent chemical elements and by identifying the crystalline phases formed. Chemical exchanges through the interface are favored by diffusion phenomena. The junction was characterized by: microscopic observations and chemical analyzes (ESEM-EDS, EPMA), X-RD and mechanical tests (HV and Shear test). Treatment at 820°C does not form a bond because the reciprocal solubilities of the chemical elements of SS and Zy-4 are very low. The junction obtained at 950°C has a reaction zone (RZ) formed at the SS/Zy-4 interface, composed of three layers. The first layer (LI = α-(Fe,Cr) on the SS side and the third layer (LIII=Zr2(Fe, Ni)) on the Zy-4 side are single-phased. The middle layer LII is biphasic (LII= e-Zr(Cr,Fe)2+Zr2(Fe, Ni)). The maximum hardness measured in the RZ is ~ 1120 HV. It is due to the formation of the intermetallic compounds of type e-Zr(Cr,Fe)2 in LII. Examination of fracture facies obtained from the joints reveals that the fracture is localized in the LIII layer and it is fragile in nature of the trans-granular type.

TIG Arc Welding - Brazing of Dissimilar Metals - An Overview

Tungsten inert gas (TIG) arc welding–brazing has been recently developed and is being increasingly implemented in various industrial applications. Nowadays, this process gains much attention in joining of dissimilar metal combinations. This review paper explains the principles underlying TIG arc welding – brazing of dissimilar metal combinations and highlights the above benefits in a number of practical applications. The process mechanism of TIG brazing is different from the conventional welding processes and it will bridge the gap between the two substrates by the addition of fillers under the concentrated heat source of TIG electrode. TIG brazing technique is one of the best alternative process among the other joining process for effective joining of dissimilar metals, which have various melting temperatures and physical properties. It is very important to understand the process mechanism and its compatibility with the various dissimilar materials joining. The present study focuses on the addressing of progress of TIG brazing process in modern days and its applications in the various industries, and to bring the awareness to the manufacturers about the importance of this process from this review report. Keywords: Tungsten inert gas (TIG) arc welding–brazing, Dissimilar metals, Microstructures, Mechanical properties.

Cold Metal Transfer (CMT) Welding of Dissimilar Materials: An Overview

In recent years, the continuous growth in manufacturing industries such as light weight structures, demands in increasing of its performance and functionality enhance the use of different materials for producing hybrid structures and thus the requirements for joining of dissimilar joints. The physical and metallurgical properties of the materials are utilised to get combined properties to achieve the product performance. On the other hand the joining methods are continuously challenging for joining of dissimilar materials. The present study reviews and describes the effective welding method of cold metal transfer for joining of dissimilar materials and its state of the art research in various materials joining. Cold metal transfer joining mechanism, capabilities of joining of dissimilar metals and their performance are reviewed. The current and emerging techniques of cold metal transfer welding method are reviewed. Methods and other technological parameters selection are described and future challenges for improving research methods on joining of dissimilar metals using cold metal transfer. Keywords: Cold Metal Transfer, MIG welding, Dissimilar materials, Mechanical properties.

Aluminum-steel dissimilar robotic arc spot welding with auxiliary insert

The authors have developed the novel process for joining dissimilar metals, which uses gas metal arc welding and an auxiliary insert or element. In this process, the element or the flanged steel rivet that has a hollow center is inserted into the pre-hole prepared in an aluminum alloy sheet for the first step. Second, the hollow center is filled with steel weld metal by arc spot welding to join the element and a steel sheet at the fixing point, and thereby the element and the steel sheet are welded strongly enough to fasten the aluminum alloy sheet between the flange of the element and the steel sheet. This new joining process is called element arc spot welding (EASW). EASW has such advantages that it can easily be applied to a dissimilar metal joint with ultra-high-strength steel; it does not need to pinch the joining metals from the upper and lower sides of the joint with a clamping tool; and the resultant shear and peel strengths of the joint are equal to or greater than those by other dissimilar metal joining processes. The prototype robot system for automating the EASW process has also been developed. In this robot system, the position of the pre-hole in the aluminum alloy sheet is detected by an image sensor, and then the tool at the tip of the robot arm moves to the detected pre-hole position to insert the element correctly into the hole; in the next step, low-spatter arc welding is carried out to fasten the aluminum alloy sheet between the element and the steel sheet.

Advances in dissimilar metals joining through temperature control of friction stir welding

Abstract

Dissimilar Metal Joining of 304 Stainless Steel to SMA490BW Steel Using the Filler Metal Powders with a High-Entropy Design

High-entropy alloys having excellent properties are particularly suitable for the application as the filler metals in welding. In the present study, multi-component mixed powders of FeCoCrNiMn and CrFeNi2.4Al0.6, based on a high-entropy design, as well as the comparative 316L stainless steel powders, were used as the filler metals, to achieve the dissimilar welding between 304 stainless steel and SMA490BW steel by laser deposition welding. By comparative analysis of the microstructure and mechanical properties of three types of joints, the feasibility and weld-ability of the filler metal powders based on a high-entropy design were studied. It was found that the melting of base metal (BM) and weld metal dilution had an impact on the set high-entropy component in the weld zone. And high-entropy structures were achieved in the weld zone by using the powders of CrFeNi2.4Al0.6. Compared to the BM of SMA490BW steel, three types of joints presented a higher notched tensile strength and had a better corrosion resistance. The joint welded using the powders of CrFeNi2.4Al0.6 had the lowest hardness value in the weld zone, in which the joint was fractured during the notched tensile tests. The other two joints fractured near the notch in the SMA490BW steel side. Transgranular fracture and a typical dimple fracture were observed in the fractured joints. In this work, multi-component mixed powders of FeCoCrNiMn and CrFeNi2.4Al0.6, based on a high-entropy design, were used as the filler metals to achieve the dissimilar welding of 304 stainless steel to SMA490BW steel by laser deposition welding. And a detailed investigation of microstructures and mechanical properties of those dissimilar joints was carried out to explore the feasibility and weld-ability of the filler metal powders based on a high-entropy design.

Nondestructive evaluation of resistance spot-welded Al-steel joints

Abstract

Investigation of Collision Surfaces and Weld Interface in Magnetic Pulse Welding of Dissimilar Al/Cu Sheets

Magnetic Pulse Welding (MPW) is an essential procedure for joining of dissimilar metals. The high velocity collision and jetting are the most important aspects of MPW controlled by welding parameters: discharge voltage and air gap. In this study, the collision surfaces and interface of MPW of pure Al and Cu are investigated. The effect of air gap on the bonding is studied by variation of the air gap from 0.7 to 4 mm. The collision surfaces of Cu and Al, the interface of welding and fracture surface were examined by optical microscope and SEM equipped with EDS analysis. The results revealed that the metallurgical bonding is obtained in the air gap of 0.7 mm, whereas higher air gaps (1 to 4 mm) result in debonding due to higher impact energy. The feature of collision surfaces depends on the physical properties of Al and Cu, the variation of collision angle and distance from the centerline of the collision. By increasing the collision angle and distance from the centerline of the collision, the porous and wavy structures in the collision surface of Al, and wavy structure with vortices in the collision surface of Cu are formed. Furthermore, by increasing the distance from the centerline of collision, the wavy structure with vortices is formed in the interface of welding. Also, the highest shear strength is obtained at the middle of the weld line, and the failure is occurred in Al.

A hybrid methodology for optimizing MIG welding process parameters in joining of dissimilar metals

In this paper application of Taguchi and Grey relational analysis methodologies in determining optimal process parameters for MIG Welding are presented. Taguchi method is widely used in designing the optimal experiments, while grey relation analysis is useful in decision making when multiple criteria’s are considered, this combination serves as an effective tool in determining the optimal parameters of the process. In the present work welding current, voltage, speed, bevel angle were considered as input parameters in joining two dissimilar metals (AISI1010 & AISI1018), as these influence the output characteristics like tensile strength and hardness, these parameters need to be optimized.