预应变对管线钢低温断裂韧度影响研究  

Effect of Prestrain on Fracture Toughness of Line Pipe Steel at Low Temperature

作　　者：肖光春[1,2] 荆洪阳[2] 徐连勇[2] 

机构地区：[1]山东轻工业学院机械与汽车工程学院,济南250353 [2]天津大学材料科学与工程学院,天津300072

出　　处：《机械工程学报》2011年第24期26-30,共5页Journal of Mechanical Engineering

基　　金：国家自然科学基金(50975196);国家自然科学基金青年科学基金(50805103);高等学校博士学科点专项科研基金(20090032110026)资助项目

摘　　要：油气管线无论是在安装还是在服役过程中,都会不可避免地产生大塑性应变(即预应变)。为了研究预应变对材料力学性能和断裂韧度的影响,对X80管线钢原材料和塑性变形材料分别进行不同温度下的拉伸试验和断裂韧度试验,并对试样断口形貌进行分析。试验结果表明,温度对管线钢的断裂韧度具有显著作用,钢材的断裂韧度随着温度的降低显著减小,断裂方式也由延性断裂转变为脆性断裂;拉伸预应变因工作硬化提高了钢材的屈服强度与抗拉强度,而压缩预应变因包申格效应降低了钢材的屈服强度与抗拉强度,但两者都降低了钢材的塑性及断裂韧度,进一步增加脆性断裂发生的概率。因此,在管道设计、选材、安全分析及评定时,应充分考虑温度和预应变对管线钢断裂行为的影响。Oil and gas pipelines may be subject to high plastic strains before they enter service and during operation.To investigate the mechanical properties and fracture toughness of line pipe steel subjected to plastic deformation with tensile or compressive prestrain,tensile tests and crack-tip-opening（CTOD） tests are conducted on X80 steel.Meanwhile,specimen fracture morphologies of different fracture modes are also analyzed.The results indicate that the temperature has a significant influence on fracture toughness of line pipe steel and the fracture toughness reduces significantly with the decreasing of temperature resulting to brittle fracture.The yield strength and tensile strength of the workpieces with tensile prestrain generally increase due to work hardening and decreased with compressed prestrain due to the Bauschinger effect.But they all significantly reduce metals plasticity and fracture toughness,and further increase the possibility of brittle fracture.Thus the effects of the temperature and the prestrain should be considered in the line pipe design,material selection and safety analysis and evaluation.

关 键 词：X80管线钢 预应变 力学性能 断裂韧度 

分 类 号：TG115[金属学及工艺—物理冶金]