Effect of external magnetic field on resistance spot welds of aluminum alloy

Effect of electromagnetic stirring on the microstructures and mechanical properties of magnesium alloy resistance spot weld

In fusion welding, gravity makes a molten metal flow downward and it sometimes causes an irregular shaped weld bead and weld defects such as an undercut. To solve this problem, the authors propose a new electromagnetic controlled molten pool welding process method which controls the molten metal flow by using upward electromagnetic forces, and the applicability of this method to industry is examined. In flat position welding with excessive heat input, the molten metal tends to sag down and an undercut defect is likely to occur. It is found that the upward electromagnetic force given by adjusting the conditions of magnetic field can lift the molten metal up, resulting in the remarkably improved shape of a penetration bead. It is further found that, even in overhead position welding, a well shaped penetration bead without undercuts is obtained by adjusting the welding touch angle as well as magnetic field conditions.

Study on the application for electromagnetic controlled molten pool welding process in overhead and flat position welding

Impact of electromagnetic stirring upon weld quality of Al/Ti dissimilar materials resistance spot welding

Feasibility study of dissimilar joining of aluminum alloy 5052 to pure copper via thermo-compensated resistance spot welding

Electromagnetic stirring method has been used in casting and arc welding processes to refine crystal grains. In this paper, the authors describe an experiment where an external magnetic field (EMF) produced by a pair of permanent magnets was used to study the effect of electromagnetic stirring on resistance spot welding of advanced high strength steel DP780. Experimental results show that under the same welding current, the EMF could refine the crystal grains, increase the weld nugget diameter, reduce the risk of shrinkage cavities and significantly improve the joint’s tensile–shear strength and ductility. However, when the welds with and without the EMF were compared under the same weld diameter, because of the greatly reduced nugget thickness, the tensile–shear strength of the weld made under the EMF is a little bit lower than the normal weld.

S. J. Hu

Papers

Quality improvement in resistance spot weld of advanced high strength steel using external magnetic field