Carbide precipitates and mechanical properties of medium Mn steel joint with metal inert gas welding

• 作者: Jiang Yang Honggang Dong Yueqing Xia Peng Li Xiaohu Hao Yaqiang Wang Wei Wu Baosen Wang
• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2021,（16）
• 页码范围: 48-58
• 页数: 11页
• 语种: 英文

摘要

Medium Mn steel was metal inert gas(MIG)welded with NiCrMo-3 and 307Si filler wires.The effect of filler wires on the microstructure and mechanical properties of joint was investigated,and the carbide precipitates were contrastively discussed.The results revealed that the microstructure of weld metal,heat-affected zone and base metal are austenite.Obvious grain coarsening occurred in the heat-affected zone(HAZ),and the maximum grain size grew up to 160 pm.In HAZ,C and Cr segregated at grain boundaries,the carbides was identified as Cr7C3.The dispersive(Nb,Mo)C phase was also found in weld metal with NiCrMo-3 filler wire.All the welded joints failed in HAZ during tensile tests.The tensile strength of welded joint with NiCrMo-3 filler wire was 675 MPa,which is much higher than that with 307Si filler wire.In comparison to base metal,higher microhardness and lower impact toughness were obtained in HAZ for these two welded joints,which was attributed to the precipitation of Cr7C3 phase and grain coarsening.The impact toughness around the fusion line is the worst for these two welded joints.