卷取温度对大变形(B+M/A)X80管线钢组织和性能的影响

Effect of Coiling Temperature on Microstructure and Mechanical Properties of(B+M/A) X80 Pipeline Steel with Excellent Deformability

通过卷取连续HOP(heating on-line partitioning)技术,使X80管线钢获取了(B+M/A)复相组织和大变形性能。采用力学性能测试、显微分析和X射线衍射方法研究了在不同卷取温度条件下(B+M/A)X80管线钢的组织演变规律,分析了显微组织对其力学性能的影响。结果表明,随着卷取温度的升高,贝氏体的含量和位错密度减小,残余奥氏体含量增加,导致材料强度降低和塑性增加。在高的卷取温度条件下,碳化物的析出和残余奥氏体的分解是材料强度增加和塑性减小的显微组织因素。在一定卷取温度下,实验钢有低的屈强比、高的均匀伸长率和和高的形变强化指数,符合大变形管线钢的技术要求。

High deformability X80 pipeline steel with microstructure composed of bainite and martinsite/austenite(B+M/A) can be obtained through the coiling continuous partitioning process. Effect of coiling temperature on the microstructure evolution and mechanical performance of the(B + M/A) X80 pipeline steel was studied by means of microscopic analysis, X-ray diffraction and mechanical property tests.The results show that with the increasing coiling temperature, the strength of the steel decreases and the ductility increases because of the decrease amount of bainite and dislocation density, as well as the increase amount of retained austenite. By a high coiling temperature, both of the precipitation of carbides and the decomposition of retained austenites result in the increase of strength and the decrease of plasticity. With a process by proper coiling temperature, the produced steel with such(B + M/A) dual- phase structure may exhibit a comprehensive mechanical performance with such as lower ratio of yield to strength, higher uniform elongation and strain hardening index, which meets the technical requirements of high deformability pipeline steel.