Study on Resistance Spot Welding Process and Properity of DH590 and Its Galvanized Steel Sheets

Dual-phase steel is one of the most widely used high-strength steels in the automotive industry, the study on the difference of resistance spot welding process and property of dual-phase steel and galvanized dual-phase steel has reference value for automobile production. The parameters were optimized by orthogonal test, the nugget diameter of the resistance spot welded joints was measured, the shear force and hardness of the spot welded joints were detected, the microstructure of the welded spots was observed. The difference of resistance spot welding process and properity of DH590 and its galvanized steel sheets were studied. The results show that the optimal parameters of DH590 spot welding process are welding current of 11.5kA, welding time of 15 cycle, electrode pressure of 2.5 kN. The galvanized steel nugget diameter is 15%-20% smaller than that of non-galvanized steel under the same welding parameters. After spot welding,the retained zinc mainly exists at the end of the fusion line. When the diameter of the nugget is equivalent, the zinc layer has no significant effect on the hardness and tensile properties of the spot welded joint.