Influencing factors of resistance spot welding performance of press-hardened steel

Objective The purpose is to study influence of welding process parameters on properties of spot welded joints of hot forming steel. Methods The orthogonal test is performed for 22MnB5 press-hardened steel. Results The order of priority affecting the mechanical properties of spot weld is welding current, electrode pressure and welding time under the condition of single pulse welding process. The best mechanical properties of the welded joint and the good welding quality can be gotten with the best welding parameters, welding current of 8.5 kA, welding time of 525 ms, and electrode pressure of 4 kN. Conclusion The press-hardened steel welded joint consists of the BM area, the tempering area, the softening area, the critical area and the nugget area. There is a serious stress concentration at the welding point joint line (nugget zone), which is a dangerous area for the failure of press-hardened steel welding joints. The last pulse small heat input can significantly reduce the stress concentration of the welding joint and improve the mechanical properties of the joint by using multiple pulse welding.