高强度管线钢焊接接头不同缺口位置的断裂韧性研究

采用夏比冲击试验，研究了X65级高频焊管、X80和X100级埋弧焊管焊接接头不同缺口位置的断裂韧性，用扫描电镜和金相方法分析了冲击试样断口特征和微观组织。结果表明，高钢级管线钢高频焊接焊缝处的断裂韧性最低，其冲击功大小与热处理工艺密切相关；而埋弧焊接热影响区断裂韧性在熔合线处最低，其主要原因是此处的组织为粗大的粒状贝氏体，而且强度越高焊接热循环对管线钢的作用越强，在熔合线附近更容易产生粗大组织，使断裂韧性降低。讨论了油气输送管道用钢管标准和技术条件对焊缝和热影响区冲击试样缺口位置的规定。

Study on Fracture Toughness of Welded Joint at Different Notch Location for High Strength Pipeline Steel

The fracture toughness of welded joint at different notch location were studied by Charpy impact test for X65 grade high frequency welded （HFW） pipe,X80 and X100 grade submerged arc welded （SAW） pipe. The fractography and microstructure of impact specimen were also studied by means of SEM and metallographic analysis. The results showed that the fracture toughness of the weld of HFW pipe was lowest. The value of absorbed energy of HFW weld was closely related to the heat treatment process. But the fracture toughness of fusion zone of submerged-arc welded jointer,its microstructure was coarse granular bainite, and was lower than the other locations of heat affected zone （HAZ） ; and with the increasing of steel strength, the effect of welding heat cycles on the pipeline steel became stronger, and form coarse microstructure in fusion zone leading to decrease fracture toughness. Furthermore, the requirements to the location of notch of impact specimen of weld and HAZ,in some standards and technical specifications of steel pipe used for petroleum and natural gas transportation were discussed.