In-situ observation of microcrack initiation and damage nucleation modes on the HAZ of laser-welded DP1180 joint  

作　　者：Junliang Xue Wei Guo Jin Yang Mingsheng Xia Guang Zhao Caiwang Tan Zhandong Wan Jiaxuan Chi Hongqiang Zhang 

机构地区：[1]School of Mechanical Engineering and Automation,Beihang University,Beijing,100191,China [2]School of Materials Engineering,Shanghai University of Engineering Science,Shanghai,201620,China [3]R&D Center,TANGSTEEL Company,HBIS Group,Tangshan,063016,China [4]Shandong Provincial Key Laboratory of Special Welding Technology,Harbin Institute of Technology at Weihai,Weihai,264209,China [5]Department of Mechanical Engineering,Tsinghua University,Beijing,100084,China [6]School of Materials Science and Engineering,Beihang University,Beijing,100191,China

出　　处：《Journal of Materials Science & Technology》2023年第17期138-149,共12页材料科学技术（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Nos.51871010 and52005022).

摘　　要：In-situ SEM can intuitively observe the changes in microstructure and microcrack initiation during the deformation process of the specimen.In this paper,the microstructural evolution,mechanical properties,and damage nucleation modes of DP1180 laser welded joints were systematically discussed by the trans-mission electron microscope(TEM),focused ion beam(FIB),and in-situ tensile test.The precipitation of carbides and disappearance of dislocations tangles deteriorated the mechanical properties of tempered martensite in the sub-critical heat affected zone(SCHAZ),which caused its microhardness slightly de-creased(∼27 HV)and also called the softened zone.The joints fractured in the SCHAZ during the tensile and Erichsen cupping tests and microcracks initiated from the tempered martensite,while the microc-rack initiation of base material(BM)occurred at the ferrite/martensite interface.The dominant damage nucleation mode of the joint was tempered martensite cracking,and that of BM was ferrite/martensite interface decohesion during tests.

关 键 词：In-situ tensile test DP steel Laser welded Damage nucleation modes 

分 类 号：TG456.7[金属学及工艺—焊接]