X90管线钢组织与性能研究

Reseach on the Microstructure and Mechanical Property of X90 Pipeline Steel

为了进一步研究第三代高强度管线钢的代表钢种X90管线钢的组织和性能,采用力学性能测试和显微组织分析方法,对比分析了两种国产X90管线钢的金相组织和力学性能。研究表明,两种管线钢在成分设计和轧制工艺上有所不同,虽然在强度性能上接近,但由于微观组织和亚结构的不同,韧性存在着较大的差异。在韧性较高的材料中,粒状贝氏体的板条束窄,且板条束呈现多位相分布,板条中含有较高的位错密度,且位错缠绕度高;此时的M/A组元多以薄膜状分布于贝氏体板条之间,使得塑性变形易于进行,因而具有较高的冲击韧性。

In order to learn more about the microstructure and mechanical properties of X90 pipeline steel, the third generation high strength pipeline steel,the mechanical and mocrostructure of two type of X90 pipeline steel had been studied by mechanical property tests and microstructure analysis. The research indicated that the composition design and rolling process of the two pipeline steels were different,the strength properties approximated,but there were large differences in toughness because of the influence of microstructure and substructure. In high toughness material,lath-like of granular bainite was narrow and showed multiphase distribution,it contained high dislocation density and the dislocation tangled. At this time,the M/A was mostly distributed as a film between the lath of bainitic ferrite,which made the plastic deformation easy,resulting higher impact toughness.