增氮结合控冷对高性能复相钢M-A组元的调控作用

项目名称： 增氮结合控冷对高性能复相钢M-A组元的调控作用

项目编号： No.51471142

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 王青峰

作者单位： 燕山大学

项目金额： 80万元

中文摘要： 申请人经初步研究发现，一种添加不同氮含量的低碳低合金钢过冷到中温区转变后空冷，形成以针状铁素体和/或低碳贝氏体为基体、马氏体-奥氏体（M-A）组元为第二相的复相组织；增氮结合适当控冷，可以调控M-A组元的内部结构和形态，使它由孪晶M-残A变为位错M-残A、组元数量及残A含量增多、硬度降低，获得了高强、高韧、高应变硬化指数和低屈强比的综合性能，制备出一种新颖的氮微合金化高性能复相钢，在抗震设计和塑性设计的大跨度建筑和桥梁上有应用前景。目前在该复相钢中，增氮结合控冷与M-A组元的内部结构和形态之间、以及后者与拉伸和冲击性能之间的内在关系，还需要深入研究。本申请拟采用计算、模拟和表征等手段，侧重研究该复相钢中增氮结合控冷对M-A组元的调控作用及机理、位错M-残A组元增塑增韧的作用及机理。该研究可望丰富复相钢的微合金化和强-塑-韧化理论，为新型高性能复相钢的设计提供参考。

中文关键词： 复相钢；M-A组元；增氮；控冷；力学性能

英文摘要： It has been revealed in our previous works that a dual-phase microstructure containing the matrix of acicular ferrite and/or low-carbon bainite and the second phase of martensite-austenite (M-A) constituent can be prepared in a low alloyed steel with low carbon content and different levels of nitrogen content by controlled transformation of supper-cooling austenite in mid-temperature interval. By intentionally added nitrogen and properly controlled cooling，the inner structure and morphology of M-A constituent can be adjusted. Namely, the twin-type martensite/retained austenite constituent is replaced gradually by dislocation-type martensite/retained austenite constituent (DM-RA, for brevity). In the same time, the fraction of DM-RA constituent with a relatively low hardness and the amount of RA is increased obviously. As a result, a new nitrogen-microalloyed dual-phase steel with high properties combining high strength, good toughness, high strain hardening exponent and low yield-to-tensile strength ratio has been produced. The application of this type of steel will be expected in the field of earthquake- and ductile deformation- resistant design structures of long-span buildings and bridges. However, until the present one cannot understand thoroughly how and why the enhanced nitrogen combined with controlled cooling affect the inner structure and morphology of M-A constituent and further affect the tensile and impactive properties. Further works should be carried out to make the correlations clear. For this effort, by means of calculation, simulation and characterization, the emphases should be paid to understanding the role of the enhanced nitrogen combined with controlled cooling in adjustment of M-A constituent and the mechanisms of improved ductility and toughness by DM-RA constituent. The results will not only enrich the fundamentals of simultaneously enhancing the strength, ductility and toughness of microalloyed dual-phase steel, but also lay a foundation for design of a new dual-phase steel with high properties.

英文关键词： dual-phase steel;M-A constituent;enhanced nitrogen;controlled cooling;mechanical properties