影响高级别管线钢拉伸强度测试的因素

Factors of Influencing on Tensile Strength Test of High Grade Pipeline Steels

采用光学显微镜、拉伸试验机等对影响高级别管线钢X80、X100、X120拉伸强度测试的指标选定、试样尺寸和形状等因素进行了分析。结果表明:对于X80以上级别管线钢用Rt0.5已经不能准确表征材料的屈服强度,使用Rp0.2或Rt0.6作为材料的屈服强度更合理;圆棒试样直径越小,拉伸试验测定的Rt0.5、Rp0.2和Rt0.6及抗拉强度值越低;由于包申格效应的影响,X80和X100钢管横向拉伸试样宜采用圆棒拉伸试样,X120钢管横向拉伸试样采用矩形拉伸试样更合理。

The factors,including index selection,sample size and sample shape,influenced on the tensile strength test of the X80,X100 and X120 high grade pipeline steels were investigated by means of optical microscope and tensile tester.The results show that Rt0.5 used for the pipeline steel whose grade was greater than X80 could not accurately characterize the material yield strength,while Rp0.2 and Rt0.6 were more reasonable.The smaller the size of the round bar specimen,the lower the Rt0.5,Rp0.2,Rt0.6 and tensile strength obtained by the tensile test.Due to the Bauschinger effect,the transverse tensile sample should adopt round bar shape for the X80 and X100 pipeline steel,and rectangular shape for the X120 pipeline steel.