Papers by Keyword: Resistance Spot Welding (RSW)

Abstract: The present study had investigated the joining performance of SiC particle reinforced aluminum metal matrix composite (Al/SiCp-MMC) having 1.0mm thickness by resistance spot welding processes. The welded joints were subjected to tensile-shearing tests in order to determine the strength of the welded zone. In addition both scanning electron microscopy (SEM) and optical microscopy (OM) were conducted to investigate the micro structural and micro hardness’s changes of the welded joints. The results reveal that: the maximum tensile-shear strength value of welded joint was obtained in these optimum welding parameters as in 17.5kA welding current for 60 periods welding. The electrode pressure was 3.5kN. It was favorable to select relatively high welding current and short welding time for improving mechanical properties of spot welded SiCp/LY12 composite joint. In this base, the welding mechanism of resistance spot welding SiCp/LY12 composite has also been discussed in detail.

Abstract: The tensile shear loads in resistance spot welding of TC4/AZ31B with addition Al power have been investigated in this paper. The results showed that the tensile shear loads with and without addition Al power were 2.636 KN and 3.692 KN when welding current was 9800A , respectivly. And the values changed 2.971 KN and 4.167 KN when the welding current was 11300A, respectively. Morphology characteristics of the welding zone were studied by scanning electron microscopy (SEM), energy dispersive spectrometer (ESD). The results suggested that the addition of Al power on the sheets of TC4 and AZ31B increased much in the tensile-shear loads when welding TC4 and AZ31B by RSW.

Abstract: In this study, in order to investigate effects of welding conditions and alloy element Cu in aluminum alloy on growth of intermetallic compounds at weld interfacial zones and weld strength of steel/aluminum alloy joints, the pure aluminum A1050 and the aluminum alloy A2017 to cold-rolling steel SPCC were welded by resistance spot welding. Two intermetallic layers were observed, and the major phases are Fe₂Al₅ adhering to the steel and FeAl₃ adhering to the aluminum. The results of EPMA suggested that diffusion of alloy element Cu in the A2017 happened at the interface, which may be the reason for that the anisotropic growth of Fe₂Al₅ might be inhibited. The tensile-shear strength of A2017/SPCC joint decreased with an increasing of the thickness of r=0.5, considering the nugget radius as 1.

Abstract: A fuzzy neural network based system was developed to control the quality of resistance spot welding. A fuzzy neural controller (FNC) was designed to realize the memory of the fuzzy neural control bases on a back propagation (BP) network, accordingly achieve the mapping of fuzzy input and output. The experiment results show that this method can compensate the multi-crossfire’s influence on the welding currency, keep a high control precision, and fulfill the demand of high precision quality monitoring to the resistance spot welding.

Abstract: The joints of RSW for HSHSS were prepared with IF spot weld equipment. The weld nugget, fracture mode, microstructure and micro-hardness of the joints were investigated. The weld nugget increases and the fracture mode changes from interfacial fracture to nugget plug fracture with the increasing welding current. There are three distinct zones in the weld joint: weld nugget, heat affected zone (HAZ) and base metal. The microstructure of HAZ includes tempered zone (HAZ-1), incomplete quenching zone (HAZ-2) and complete quenching zone (HAZ-3). The micro-hardness of weld nugget and HAZ-3 is same with the base metal. The micro-hardness of HAZ-1 and HAZ-2 is smaller than that of base metal.

Abstract: The resistance spot welding between commercially pure titanium and stainless steel was achieved using an aluminum alloy insert. The interfacial microstructure and mechanical properties of the joint were investigated. The maximum tensile shear load of 5.38 kN was obtained from the Ti/SUS304 joint welded at the welding current of 10 KA. The results reveal that the property of the Ti/SUS304 joint can be improved by using an aluminum alloy insert between Ti and SUS304 sheet.

Abstract: In order to obtain better understanding of the resistance spot weldability of magnesium alloy and provide some foundational information for improving mechanical properties of the magnesium alloy joint, the influencing factors of pore formation during resistance spot welding of magnesium alloy, such as preexisting pores in base material, hydrogen rejection, shrinkage strain and expulsion, were analyzed; the corresponding restraining measures were discussed. The analyses reveal that the shrinkage strain and expulsion are important factors in contributing to the formation of pores during resistance spot welding of magnesium alloy, and that the pore formation could be suppressed by adjusting welding parameters.

Abstract: The effect of copper strips as an insert material on electrode failure has been studied during spot welding of galvanized sheets. The results showed that an extended electrode lifetime was obtained due to the use of copper strips between electrode and workpiece which prevented electrode from alloying with molten zinc and lowered the temperature of electrode tip. In addition, the presence of inserted copper strip increased the resistance of welding system, thus generated much more heat to form larger nugget The electrode degradation mechanism was basically caused by deformation at electrode tip and wear.

Abstract: Modeling of resistance spot welding process on galvanized steel sheet was investigated. Mathematical models developed by nonlinear multiple regression analysis and artificial neural network approach were employed in the prediction of welding quality factors, namely nugget diameter, penetration rate and tensile shear strength, under some welding conditions. According to the prediction models on quality, the prediction systems of welding process parameters were formulated respectively on the basis of Newton-Raphson iterative algorithm and cascade forward back propagation algorithm in order to obtain the desired welding quality. The results showed that the prediction precision of cascade forward back propagation algorithm was higher than Newton-Raphson iterative algorithm. The current duration had the largest prediction error, followed by electrode force and welding current. Therefore, it was concluded that the current duration was the most difficult parameter in prediction system of welding process in order to obtain the desired welding quality.

Abstract: Resistance Spot Welding (RSW) is a widely used technology. And the rapid wear is the main reason for the short life of RSW electrodes. To improve electrode life during RSW, a novel ultrasonic-aided electro-spark deposition technology (UESD) and device are proposed in this paper. The WC metallurgical bond coating was fabricated on the surface of CuCr1 electrodes by UESD, and some experimental results were also analyzed. Moreover, the surface morphology of WC coating was studied by SEM and the quality of coating wear resistance was analyzed through experimental method. This study provides a novel way to extend the life of common moulds and RSW electrodes.