Q&P980CR steel resistance spot welding process optimization
LIU Quanlong;KONG Liang;WANG Min;LEI Ming;Shanghai Key Laboratory of Material Laser Processing and Modification,Shanghai Jiao Tong University;Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration;Baosteel Research Institute,Baoshan Iron & Steel Co.,Ltd.;
In this paper,the resistance spot welding of QP980CR steel under conventional welding parameters is studied. Due to the high carbon equivalent of QP980 base metal,the joints contain much hardening structure and manifest poor plasticity,resulting in interface fracture in the tensile-shear tests. Thus,the optimization scheme with the additional postheat current pulse is put forward.Based on SORPAS numerical simulation,the influence of the postheat pulse welding current and welding time on the cooling rate of section-t_(8/5) of the welding joints is studied,and the optimized welding parameters are determined. The experimental results show that the postheat current pulse increases the tensile-shear strength and cross-tension strength of the welding joints,and the failure mode of the joints changes from interface fracture to pullout fracture,indicating that the postheat current pulse effectively reduces the cooling rate and improves the toughness of the welding joints.
【CateGory Index】： TG453.9