Effects of electrode force on microstructure and mechanical behavior of the resistance spot welded DP600 joint

In this paper, the effects of electrode force on the mechanical properties, weld nugget size, failure mode, microstructure and microhardness of the resistance spot welded dual-phase steel joint were investigated experimentally. The results indicate that different electrode forces generate different weld nugget sizes and there is a critical electrode force with which the weld nugget size and mechanical properties of the welded joint can accomplish their maximum values. The mechanical properties and failure modes of the welded joint are directly associated with the weld nugget size. In addition, the electrode force also alters the microscopic structure and grain size of the welded joint, but has a weak effect on the microhardness and martensite content of the welded joint.

► Effects of electrode force on performance indices of welded joint were investigated.
► Electrode force alters the microscopic structure and grain size of the welded joint.
► Electrode force weakly affects the microhardness and martensite content of the joint.
► Different electrode forces result in different weld nugget sizes.
► The welded joint has the best performance with a critical electrode force.