Spot welding

About: Spot welding is a research topic. Over the lifetime, 12491 publications have been published within this topic receiving 89845 citations. The topic is also known as: Spot_welding.

Evaluation of weldability for resistance spot welded single-lap joint between GA780DP and hot-stamped 22MnB5 steel sheets †

Abstract: Recently, in the automotive industry, Al-coated boron steel sheets (22MnB5) have been used for hot stamping, and the use of these sheets makes it possible to achieve a tensile strength of over 1,500 MPa, since a metallurgical transformation from austenite to martensite occurs during the process. In this study, resistance spot welding (RSW) experiments were performed in order to evaluate the weldability of single-lap joints between GA780DP and 22MnB5. The effect of the weld current on the nugget diameter and load-carrying capacity was evaluated by observing the nugget diameter and performing a tensile-shear test. Furthermore, the fracture behavior was evaluated by carrying out optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) observations. Ductile regions were observed on the interfacially fractured surface of the weld, and this implies that a high load-carrying capacity can be obtained even when interfacial fracture (IF) occurs. IF is caused by the stress concentration resulting from the presence of the sharp notch at the boundary of the nugget as well as by the high hardness and the brittle microstructure of the weld; the microstructure is brittle because of the high carbon equivalent (Ceq) and the penetration of Al in the weld.

Improving reliability of heat and fluid flow calculation during conduction mode laser spot welding by multivariable optimisation

Abstract: Several uncertain parameters affect the reliability of heat transfer and fluid flow calculations during conduction mode laser spot welding because their values cannot be prescribed from fundamental principles. These parameters include absorptivity of the laser beam, effective thermal conductivity and effective viscosity of liquid metal in the weld pool. Values of these parameters are usually adjusted by trial and error so that the computed results agree with the corresponding experimental values. Here it is shown that by integrating multivariable constrained optimisation with convective heat transfer and fluid flow calculations, the values of the uncertain parameters can be obtained from a limited volume of experimental data. The optimisation technique requires numerically calculated sensitivity values of weld dimensions with respect to absorptivity, effective thermal conductivity and effective viscosity and minimises the discrepancy between the predicted and the measured weld dimensions. The nume...

Electrode for spot welding

Abstract: Spot welding electrodes with generally dome shaped welding faces are provided with surface features for welding both aluminum alloy sheet assemblies and steel sheet assemblies. A raised circular plateau is formed on the central axis of the dome and, in one embodiment, a suitable number of round bumps are formed in concentric spacing from adjacent the circumference of the plateau toward the circular edge of the welding face. For welding steel workpieces the plateau mainly serves as the engaging feature of the electrode. Both the plateau and concentric bumps are used in penetrating light metal surfaces for suitable current passage. In another embodiment, the domed surface is shaped with concentric terraces for engagement with the workpieces.