X70大变形管线钢管的组织和性能

Microstructure and Properties of X70High Deformability Linepipe

通过拉伸试验测定了X70大变形管线钢管的屈服强度Rt0.5、抗拉强度Rm、屈强比Rt0.5/Rm、应力比、均匀变形伸长率,并对比了系列温度下的冲击韧性,分析了管体的显微组织以及-100℃冲击断口的形貌。结果表明:管体纵向具有优异的拉伸性能,最小的Rt0.5为478 MPa,Rt0.5/Rm低于0.69,均匀变形伸长率大于11%;-100℃时的横向冲击吸收能为120J,剪切断面率为90%;断口呈韧性断裂特征,管材具有良好的低温韧性,韧脆转变温度低于-100℃;该管线钢是以铁素体、粒状贝氏体为主的双相组织,管体中心存在显著的粒状贝氏体带。

The yield strength, tensile strength, yield ratio, stress ratio, umtorm elonganon ot A,v -,s- deformability linepipe were tested by tensile experiment. The impact toughnesses at different temperature were compared. The microstructure and impact fracture morphology of the line pipe at - 100 ℃ were analysed. The results show that the linepipe had excellent longitudinal tensile properties, the lowest value of Re.s was 478 MPa, Rt0.5/Rm was lower than 0.69 and the uniform elongation was higher than 11 . The transverse absorption energy of the linepipe at --100 ℃ was 120 J and the shear section rate was 90%, the ductile fracture showing that the steel had good toughness properties at low temperature and the ductile-brittle transition temperature was lower than 100℃. The main mierostructure of the linepipe were ferrite and granular bainite. The granular bainite hand significantly existed in the center of the line pipe.