Research For Resistance Spot Welding Performance Of Hot Stamping Tailor Rolled Blank

Lightweight is one of the important means to achieve energy saving and emission reduction in automobiles.Preparation of high-strength hot stamping parts by rolling differential plates of 22MnB5 steel,plate thickness can be designed according to load distribution,thereby achieving lightweight bodywork while ensuring safety.Hot stamped body parts prepared from 22MnB5 rolled differential plates need to be spot welded to other parts of the body in practical applications.At this time,the thickness variation of the rolled differential plate will affect its welding performance.This paper is related to the study of the thickness effect to promote the practical application of differential plate hot stampings.Determining welding parameters of 22MnB5 with DP590 and HC340 respectively by exploratory experiment.22MnB5 and DP590 with welding current 9.5kA,welding time 15cyc,electrode pressure 0.15MPa,maximum tensile force reach 12.52kN.22MnB5 and HC340 with welding current 10.0kA,welding time 16cyc,electrode pressure 0.15MPa,maximum tensile force reach 13.55kN.We found that the maximum tensile and shear force increases with the increase of plate thickness.Experiments show that its hardness increases as well.Microstructure photographs show welding joints consist of three parts welding nugget zone,heat affected zone and base metal zone.22MnB5 steel base metal zone mainly for fine martensite with highest intensity.22MnB5 steel heat affected zone mainly for tempered martensite.Strength lower than nugget zone and base metal zone this area.And DP590 steel base metal zone mainly for a small amount of martensite is distributed in a large amount of ferrite.DP590 steel heat affected zone mainly for ferrite and martensite.HC340 base metal zone mainly for ferrite.HC340 steel heat affected zone mainly for two-phase zone of ferrite and martensite.And the closer to the nugget zone,the bigger the grain is.