Tensile Strength Of Dissimilar Joints Research Articles

The study investigates the effects of tool pin length, rotation speed, and dwell time on the microstructure and tensile strength of dissimilar joints between low-carbon galvanized steel and aluminium T6-6061 through friction stir spot welding

Friction stir welding is an efficient method for joining steel and aluminum plates at a point of disturbance. In many studies, the tool is only introduced into the aluminum plate, avoiding penetration into the steel plate due to its high strength and the need for a robust tool. Under such conditions, the created connection usually possesses low mechanical properties. In this research, by increasing the strength of the H13 steel tool through thermal operations, the possibility of penetration and bonding of aluminum 6061 with galvanized low-carbon steel has been provided. Moreover, by penetrating the steel plate, the integration of galvanized layers in the disturbance region has been facilitated. The examined variable parameters include pin length, rotational speed, and tool dwell time. Mechanical properties such as tensile strength, fracture force, and Vickers hardness were investigated. Furthermore, the weld microstructure and intermetallic layers were examined using scanning electron microscopy (SEM) and EDS analysis. Tensile and shear strength increase with an increase in pin length, rotational speed, and tool dwell time. Shear fracture loading showed a decrease with increasing pin length, then reached its maximum value when using long pins, while continuously increased with higher rotational speed and longer tool dwell time. As we approach the center of the weld in both the steel and aluminum parts, smaller grain sizes are observed due to increased plastic deformation, more material mixing, and increased mechanical tool pressure, while in the heat-affected zone, a coarse grain structure forms. Hardness in the aluminum plate decreased in the heat-affected zone and reached its minimum value in the thermo-mechanical-affected zone, then increased to the maximum value in the nugget zone, while hardness changes in the steel plate were uncertain. The most influential parameter on mechanical and microstructural properties was pin length, followed by rotational speed and tool dwell time.

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.

Effects of groove on the microstructure and mechanical properties of dissimilar steel welded joints by using high-entropy filler metals

Owing to the high strength and plasticity, high-entropy alloys (HEAs) can be used as filler metals to achieve high-quality joints. However, the melting base metal in fusion welding can significantly change the chemical composition of the weld zone (WZ), which may cause the failure of high-entropy effects in the WZ. In the present study, a high-entropy filler metal of CoCrNiMnAl0.6Ti0.3Si0.1 was used to join the dissimilar metals of SMA490BW steel and 304 stainless steel. Two types of joints were obtained by whether the welding plates had a V-groove or not. The effects of workpiece groove on the microstructure, element distribution, phase structure, microhardness, and tensile strength of dissimilar joints, as well as the controllability of the high-entropy effects in WZ were explored. It was found that a 60° V-groove in the workpiece could significantly reduce the amount of Fe element in the WZ. Microstructures in the WZs were changed from columnar/equiaxed grains of the No V-groove sample to lamellar structures of the V-groove sample. The microhardness in the WZ of the latter was 33% higher than that of the former. The reason was mainly related to the phase structures in two WZs. Two types of samples had a similar notched tensile strength, which was higher than SMA490BW steel, and lower than 304 stainless steel.

Microstructure and mechanical properties of electron beam welded TC4/TA7 dissimilar titanium alloy joint

Dissimilar titanium alloys TC4/TA7 are welded by using electron beam welding (EBW), and the microstructure and mechanical properties of welded joints are systematically investigated. Results show that the microstructure in different zones of welded joint is obviously different. The fusion zone (FZ) is mainly composed of fine α′ martensite. The heat-affected zone (HAZ) of TC4 side is composed of martensite, blocky α phase, original α phase and β phase. The HAZ of TA7 side consists of a small amount of martensite, blocky α phase and original α phase. TEM analysis shows that, due to the effect of modification welding, the martensite becomes coarser in the upper part of joint, and dislocations are generated in FZ. Element line scanning and elemental maps analyses indicate that the distribution of alloying elements is relatively uniform at joint interface, and no obvious segregation is occurred. The distribution of hardness in weld zones is ranked as follows: FZ > HAZ of TC4 side > TC4 base metal (BM) > HAZ of TA7 side > TA7 BM. The tensile strength of dissimilar joint is slightly higher than that of TA7 BM, while its elongation is slightly lower than those of the two BMs. The joint fails in the side of TA7 BM during stretching, and the morphology dominantly presents the characteristic of ductile fracture.

Optimization of TIG Welding Process Parameters for X70-304L Dissimilar Joint Using Taguchi Method

The optimization of mechanical properties of the welded joints requires a statistical approach such as Taguchi experimental designs associated with experimental techniques and laboratory characterizations. The aim of this work is to propose a method of optimization of the mechanical performances of a TIG dissimilar welding of two grades of steels: a high strength low alloy steel X70 and an austenitic stainless steel 304L. The experimental designs were chosen according to the Taguchi method L9. The metallurgical characterization includes optical microscopy, SEM microscopy, EDX analyses and mechanical tests to establish a relationship between welding parameters, microstructures and mechanical behavior in different zones of a dissimilar weld joint. The results showed that the hardness is more strongly related to microstructural evolution than tensile strength of dissimilar joint. It was found that gas flow is the main significant TIG welding parameter affecting dissimilar weld characteristics.

Evaluating the tensile strength of friction welded (AA6061 & AA7075-T6) dissimilar joints by using response surface methodology

This paper aims at formulating a numerical model to predict and optimize the friction welding (FW) process parameters on the tensile strength of the dissimilar, (AA6061/AA7075-T6) aluminium alloy joints. The ultimate tensile strength of friction welded dissimilar joints can be obtained by varying the FW parameters within the process windows. The response surface methodology (RSM) was identified as the method for optimizing the FW process parameters to maximize the tensile strength of dissimilar joints and the optimized parameters were accounted. Finally, the characterization of specimens at the weld zone was studied by using scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS) and optical microscope (OM).

Influence of laser peening on the tensile strength and impact toughness of dissimilar welds of Inconel 625 and UNS S32205

The present study addresses the effect of fillers on the microstructure and tensile strength of dissimilar joints of Inconel 625 and UNS S32205 by pulsed current gas tungsten arc welding (PCGTAW) employing ERNiCrMo-10 and ERNiCrMo-14 fillers. This study attested that tensile failure occurred in the fusion zone of the dissimilar joints for both the cases in the as-welded un-peened condition. Double shot laser shock peening (DLSP) was performed on the fusion zone of these PCGTA welds on the cap and root regions of the weldments. It was assimilated that after DLSP on the cap and root regions of the weldments, the yield and tensile strength of the welded joints employing these fillers were improved considerably. Residual stress analysis were carried out on the dissimilar coupons using X-ray Diffraction analysis. The results demonstrated that after subjecting to double sided DLSP, the fusion zones were subjected to compressive residual stresses. The present study articulated that shot peening using low energy laser beam resulted in better tensile strength.

Large spot laser assisted GMA brazing–fusion welding of aluminum alloy to galvanized steel

Through positioning the leading laser as an auxiliary role, and the trailing arc as the main heat source, aluminum alloy (Al) was joined to galvanized steel plate with lap joint. The brazed seam width w increased with the increasing of heat input. The appropriate laser-wire distance Dlw and defocusing distance df to obtain the good fusion weld appearance were 5mm and +20mm, respectively. The fracture position of tensile test sample was divided into brazed interface fracture (P<0.6kW) and HAZAl fracture (P>0.6kW). The maximum tensile strength of dissimilar joint reached 75% of that of Al. The shear strength was mainly decided by heat input, and the brazed seam had the highest microhardness. Joining mechanism of this process was summarized into two factors: the effective function of laser and the metallurgical function of zinc. Compared to gas metal arc welding (GMAW), large spot laser assisted GMA process improved weld appearance and enhanced the process stability and its time-efficiency.

Effect of Tool pin Profile and Axial Force on Tensile Behavior in Friction Stir Welding of Dissimilar Aluminum Alloys

Aluminium alloys generally has low weldability by traditional fusion welding process. The development of the Friction Stir Welding (FSW) has provided an alternative improved way of producing aluminium joints, in a faster and reliable manner. FSW process has several advantages, in particular the possibility to weld dissimilar aluminium alloys. This study focuses on the behavior of tensile strength of dissimilar joints of AA6351-T6 alloy to AA5083-H111 alloy produced by friction stir welding was analysed. Five different tool pin profile such as Straight Square (SS), Tapered Square (TS), Straight Hexagon (SH), Straight Octagon (SO) and Tapered Octagon (TO) with three different axial force (1tonne, 1.5tonne, 2 tonne) have been used to weld the joints. The effect of pin profiles and axial force on tensile properties and material flow behaviour of the joint was analyzed and it was found that the straight square pin profile with 1.5 tonne produced better tensile strength then other tool pin profile and axial force.

Mechanical properties of friction welded 6063 aluminum alloy and austenitic stainless steel

Friction welding of dissimilar metal combination of aluminum alloy and austenitic stainless steel was examined to investigate the effect of welding conditions on mechanical properties of the dissimilar metal combination. The welded joints were produced by varying forge pressure (Fg), friction pressure (Fr), and burn-off length (B). The joints were subjected to mechanical testing methods such as the tension, notch Charpy impact tests. The tensile strength and toughness decrease with an increase in friction pressure. The tensile strength decreases with an increase in burn-off length at a low forge pressure while tensile strength increases with an increase in burn-off length at a high forge pressure. The tensile failure of the welded joint occurred in aluminum alloy just away from interface in the thermo-mechanically affected zone indicates good joint strength at the condition of low friction pressure, high forge pressure, and high burn-off length. The maximum tensile strength was observed with low friction pressure and high forge pressure. The tensile strength of dissimilar joint is approximately equal to tensile strength of 6063 aluminum alloys at the condition of low friction pressure, high forge pressure, and high burn-off length. The tensile and impact failure of joints was examined under scanning electron microscope and failure modes were discussed.