超低碳微合金管线钢焊接接头的组织与冲击性能

Microstructure and Impact Property of Welding Joints of Ultra Low-Carbon Micro-Alloyed Pipeline Steel

利用光学显微镜、冲击试验机及扫描电镜等对超低碳微合金管线钢焊接接头的组织及冲击性能的进行了研究。结果表明:超低碳微合金管线钢母材组织主要由粒状贝氏体和贝氏体铁素体组成,接头的粗晶热影响区组织为贝氏体铁素体、粒状贝氏体和少量的多边形铁素体及细小的M-A岛,且晶粒粗大,焊缝中的针状铁素体以钛、铝、硅、锰的复合氧化物诱发形核,并以筐篮的编织结构相互交错分布;在-10℃时此接头的冲击功可达178 J,表现为韧性断裂。

Using optical microscopy,impact test and scanning electron microscopy,the microstructure and toughness of welding joints of an ultra low-carbon micro-alloyed pipeline steel were studied. The results show that the microstructure of the ultra low-carbon micro-alloyed pipeline steel mainly consists of granular bainite and bainite ferrite. The coarse grained region of heat-affected zone is composed of bainite ferrite,granular bainite,a small amount of polygon ferrite and fine M-A island,and the grains are obviously coarse. The nucleation of acicular ferrites in weld line is induced by composite oxides containing Ti,Al,Si and Mn,and the acicular ferrites distribute as interlaced basket woven structure. The impact energy of the joints was 198 J at- 10 ℃. And the fracture mode of the joints in impacting is ductile fracture.