终冷温度对X90管线钢组织和性能的影响

利用力学性能测试和材料显微分析等试验技术，研究了终冷温度对X90管线钢组织与性能的影响规律。研究表明，通过在线热处理工艺，X90管线钢可获得贝氏体+马氏体/奥氏体(B+M/A)双相组织。随着终冷温度的上升，试验钢的贝氏体含量降低，马氏体/奥氏体含量增加，导致材料屈服强度下降，塑性升高。当终冷温度为350 ℃时，试验钢的强韧性较高，组织以贝氏体为主。B+M/A双相组织使得试验钢的屈强比为0.90，均匀伸长率为19.5%，形变强化指数为0.11，满足大变形管线钢的使用要求。

Influence of Quenching Temperature on Microstructure and Properties of X90 Pipeline Steel

The influence rule of the quenching temperature on X90 pipeline steel microstructure and properties was studied through mechanical property test and material microscopic analysis technology etc. The results indicated that(B+M/A) dual-phases microstructure can be obtained through online heat treatment process. With the increasing of quenching temperature, the content of bainite decreases and content of martensite/austenite increases, which lead to the decrease of yield strength and increases of plasticity. When the quenching temperature is 350 ℃, the strength and toughness of experimental steel are higher, and the microstructure mainly consists of bainite. This(B+M/A) dual-phase structure makes the yield ratio 0.90, uniform elongation 19.5% and strain hardending index 0.11 for the experimental steel, all these meet the technical requirements for large deformation pipeline steel.