825镍基复合管热丝TIG焊接接头组织与性能分析

Microstructure and properties of hot-wire TIG welded joints of 825 nickel-base clad pipe

采用热丝TIG焊接方法对L360QS/N08825双金属复合管进行焊接,并研究分析了焊接接头的显微组织和性能。结果表明:焊缝中心的显微组织较为均匀,大部分为胞状晶,过渡层存在少量柱状晶,盖面层存在少量树枝晶;常温下焊接接头的平均抗拉强度为521 MPa,为典型的韧性断裂;-30℃下焊缝及热影响区的冲击吸收功分别为120 J和231 J,断口分析表明分别为混合式断裂和韧性断裂;热影响区及焊缝硬度明显高于母材,根焊层焊缝区硬度约为265 HV,明显高于其他焊道。

L360QS/N08825 hi-metal clad pipe was welded by hot wire TIG,and the microstructure and mechanical properties of the welded joint were then analyzed. The results show that uniform cellular crystal dominated the microstructure,only a small amount of column crystal and dendritic crystal can be observed in the transition layer and cover welding respectively ;the average tensile strength is 521 MPa at room temperature,and the fracture morphology shows a typical ductile fracture; the impact absorbing energy of welding bead and heat allotted zone was 120 J and 231 J respectively,the fracture morphology implying the fracture modes was mixed fracture and ductile fracture; the microhardness of heat-affected zone is higher that of the welding head; the maximum value is about 265HV,which occurs in the root bead layer and is apparently higher lhan others.