Comparison investigation on microstructure and properties of dissimilar welds by laser alignment welding and laser offset welding between Al-Si coated 1.5 GPa and novel 2 GPa press hardened steels  

作　　者：Hao-han Min Qian Sun Ya-jun Xing Hong-liang Liu Yu Chen Xiao-nan Wang Li-ning Sun 

机构地区：[1]School of Mechanical and Electrical Engineering,Soochow University,Suzhou,215002,Jiangsu,China [2]Technology Research Institute of Bengang Steel Plates Co.,Ltd.,Benxi,117000,Liaoning,China [3]Shagang School of Iron and Steel,Soochow University,Suzhou,215137,Jiangsu,China

出　　处：《Journal of Iron and Steel Research International》2024年第10期2413-2422,共10页钢铁研究学报（英文版）

基　　金：financially supported by the funds of the National Natural Science Foundation of China(Nos.52005357 and U1908224);the support of Postdoctoral Research Foundation of China(2022M712308);Liaoning Revitalization Talents Program(No.XLYC2007066).

摘　　要：Press hardened steel(PHS)plays a key role in the manufacture of anti-collision structural components.The formation of δ-ferrite is a suffering issue for the laser welding of Al-Si coated PHS.Oscillating laser was used to weld Al-Si coated 1.5 GPa PHS and novel 2 GPa PHS,and the effect of laser offset on the microstructure and properties of the dissimilar welded joints was studied.The results showed that a perfect weld profile was achieved by laser offset welding(LOW),without any welding defects.The δ-ferrite formed in as-received welds of laser alignment welding(LAW)with high Al content(up to 2.9 wt.%),but it disappeared with the laser offset to 2 GPa PHS,and the maximum Al content in the segregation zone reduced to 1.2 wt.%.After post-welding heat treatment,the δ-ferrite was coarsened and theα-ferrite formed in the secondary Al-rich area for the high Ac3 temperature,but the α-ferrite was few and fine in LOW welds.The hardness in the LAW welds was lower than that in the LOW welds,due to the presence of δ-ferrite,as well as less carbon content and Ti and V alloying elements.The tensile strength(1561 MPa)and elongation(5.4%)with LOW were higher than those with LAW(1490 MPa,3.1%),and the fracture occurred in the Al-Si coated PHS.It is indicated that adjusting the laser offset is effective to prevent the formation of δ-ferrite and is potential to avoid the formation of α-ferrite.It also provides a wide heat treatment temperature window for the dissimilar welds of 1.5 GPa PHS and novel 2 GPa PHS.

关 键 词：Al-Si coated press hardened steel 2 GPa press hardened steel Laser offset welding δ-ferrite Property 

分 类 号：TG456.7[金属学及工艺—焊接]