终冷温度对X100管线钢组织与性能的影响

Effect of final cooling temperature on microstructure and properties of X100 pipeline steel

利用在线加热配分(HOP)技术,可使X100钢获得(B+M/A)复相组织和大变形性能。采用力学性能测试、材料显微分析和X射线衍射方法研究了(B+M/A)X100管线钢在不同HOP终冷温度条件下的组织与性能特征。结果表明,随着终冷温度的升高,试验钢贝氏体的板条宽度增加,贝氏体的含量和位错密度减小,导致材料强度降低和塑性增加。在高的终冷温度条件下,马氏体的形成、碳化物的析出和残留奥氏体的分解导致材料强度增加和塑性降低。但是,在本试验所采用的不同终冷温度下,试验钢的屈强比均不高于0.80,均匀伸长率均不低于8%,形变强化指数大于0.10,符合大变形管线钢的技术要求。

Multiphase structure of bainite and M / A constituent and high deformability can be obtained for X100 pipeline steel through HOP（ Heating On-line Partitioning） technology. Microstructure and properties characteristics of（ B ＋ M/A） X100 pipeline steel at different final cooling temperatures during accelerated cooling of HOP were investigated by means of mechanical properties test,microscopic analysis and X-ray diffraction method. The results show that with the increasing of final cooling temperature,the strength decreases and the ductility increases for the tested steel because of the widening of bainite lath,the decrease of bainite content and dislocation density. But the strength increases and the ductility decreases because of the formation of martensite,the precipitation of carbides and the decomposition of retained austenite in a high range of final cooling temperature. However the yield ratio is not higher than 0. 80,uniform elongation is not lower than8% and strain hardening exponent is higher than 0. 10 for the tested steel at the all final cooling temperatures used in the test,which meet the technical requirements to high deformation pipeline steel.