采用热丝TIG焊对X80钢板进行对接,并研究了接头的显微组织和力学性能.结果表明:焊缝区主要为针状铁素体(AF)组织,热影响区粗晶区主要为贝氏体铁素体(BF)和粒状贝氏体(GB)组织,细晶区主要是多边形铁素体(PF)和少量贝氏体组成;焊接接头的平均抗拉强度为643 MPa,断裂在母材区;在-30℃时焊缝区的冲击吸收功高于热影响区,焊缝主要是韧脆混合断裂为主,而HAZ主要以脆性断裂为主.焊缝区的硬度较高,焊接接头HAZ存在硬化和软化现象.%Hot-wire TIG was used to weld X80 pipeline steel plate,the microstructure and mechanical properties of the welded joint were analyzed.The results show that:the microstructure of weld zone is acicular ferrite(AF),the microstructure of the coarse grain heat-affected zone is granular bainite(GB) and bainite ferrite(BF),and the microstructure of the fine grain heat-affected zone is polygonal ferrite(PF) and bainite;the average tensile strength of the welded joint is 643 MPa at room temperature.At-30 ℃,the impact absorption of weld zone is higher than that of heat affected zone,the weld is mainly composed of ductile and brittle fracture,and HAZ is mainly brittle fracture.The microhardness of the welded zone is higher than others,softening and hardening are founded in the heat-affected zone.
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