论文部分内容阅读
对低碳贝氏体钢进行双面埋弧焊焊接,并用光学显微镜和PSW750型示波冲击试验机对焊接接头进行表征,研究了钢的显微组织和低温韧性。结果表明:低碳贝氏体钢双面埋弧焊后,焊缝区的组织为针状铁素体和粒状贝氏体;HAZ的组织为贝氏体铁素体和粒状贝氏体;HAZ熔合线附近的硬度最高,远离熔合线硬度降低并逐渐接近母材金属的硬度;随着温度的降低焊接过程中的凝固偏析、高度集中的位错源来不及松弛应力集中以及分布在晶界上的Ti、Mo等微合金元素形成的碳氮化物,导致焊接接头焊缝区和HAZ韧性降低并在-20℃和-60℃发生韧脆转变。
The low carbon bainitic steels were welded by double-sided submerged arc welding. The welded joints were characterized by optical microscope and PSW750 oscillometric impact tester. The microstructure and low temperature toughness of the steels were studied. The results show that the microstructure of the weld zone is acicular ferrite and granular bainite after biaxial submerged arc welding of low carbon bainitic steel. The microstructure of HAZ is bainitic ferrite and granular bainite. HAZ The hardness near the fusion line is the highest, the hardness away from the fusion line decreases and gradually approaches the hardness of the base metal. With the decrease of the temperature, the segregation of the solidification in the welding process is less concentrated than the relaxation stress and distributed in the grain boundary Ti, Mo and other micro-alloying elements such as carbonitride, resulting in weld zone weldability and HAZ toughness decreased and at -20 ℃ and -60 ℃ ductile-to-brittle transition.