Microstructure and mechanical properties of ultralow carbon high-strength steel weld metals with or

• 作 者: Xing-hai Yang Xiao-hua Chen Shi-wei Pan Zi-dong Wang Kai-xuan Chen Da-yong Li Jun-wei Qin
• 机 构: School of Material Science and Engineering,University of Science and Technology Beijing,Beijing 1000
• 出 处: 矿物冶金与材料学报
• 发表日期: 2021年1期
• 关键词: weld metal microstructure mechanical properties hardenability grain coarsening

Two types of ultralow carbon steel weld metals (with and without added Cu?Nb) were prepared using gas metal arc welding (GMAW) to investigate the correlation between the microstructure and mechanical properties of weld metals.The results of microstructure characterization showed that the weld metal without Cu?Nb was mainly composed of acicular ferrite (AF),lath bainite (LB),and granular bainite (GB).In contrast,adding Cu?Nb to the weld metal caused an evident transformation of martensite and grain coarsening.Both weld metals had a high tensile strength (more than 950 MPa) and more than 17％elongation;however,their values of toughness deviated greatly,with a difference of approximately 40 J at?50°C.Analysis of the morphologies of the fracture surfaces and secondary cracks further revealed the correlation between the microstructure and mechanical properties.The effects of adding Cu and Nb on the microstructure and mechanical properties of the weld metal are discussed;the indication is that adding Cu?Nb increases the hardenability and grain size of the weld metal and thus deteriorates the toughness.