复相化钻杆在循环应力下断裂行为研究  

Research on Fracture Behavior under Cyclic Stress of Drill Pipe with Microduplex Structure

作　　者：何石磊[1,2] 蔡和平[1] 薄国兵 

机构地区：[1]西安交通大学材料学院,陕西西安710049 [2]国家石油天然气管材工程技术研究中心,陕西宝鸡721008 [3]渤海装备中成机械制造公司,天津300280

出　　处：《钢管》2013年第6期14-19,共6页Steel Pipe

摘　　要：采用疲劳试验、扫描电镜动态拉伸装置和透射电镜,研究了复相化钻杆的疲劳强度和在循环应力作用下裂纹萌生、扩展的特点,并分析讨论了显微组织对钻杆疲劳断裂行为的影响。研究结果表明:下贝氏体组织或下贝氏体/马氏体界面可使钻杆的显微断裂模式由沿晶+穿晶断裂转变为穿晶断裂,增加了裂纹转折和二次裂纹,提高了材料的裂纹扩展抗力。在钻杆材料中引入适当比例的下贝氏体+马氏体复相组织,明显增长了裂纹萌生周期,可使钻杆在机械性能相近情况下具有优于回火索氏体组织的疲劳性能。The fatigue strength and characteristics of crack initiation and propagation under cyclic stress of the drill pipe with microduplex structure are studied by fatigue testing machine, scanning electron microscopy dynamic tensile device and transmission electron microscopy. And the effect by microstructure on fatigue fracture behavior of the said drill pipe is analyzed and discussed.The results show that the evolution of the micro-fracture mode from intergranular-transgranular fracture to transgranular fracture may appear because of introducing low bainite structure or bainite ＋ martensite interface. As a result, the deflection of cracking direction and secondary cracking are increased, and the resistance of the material against crack propagation is accordingly enhanced. Therefore it is possible for the the drill pipe to obtain fatigue performance better than that in case of tempered sorbite structure, and still keep similar mechanical properties by means of introducing an appropriate proportion of low banite/martensite duplex structure which leads to a longer crack initiation cycle.

关 键 词：钻杆 下贝氏体+马氏体 复相组织 循环应力 二次裂纹 断裂行为 疲劳性能 

分 类 号：TE921.2[石油与天然气工程—石油机械设备]