相变诱导高强度高塑性纳米超细晶钢及变形机理研究

项目名称： 相变诱导高强度高塑性纳米超细晶钢及变形机理研究

项目编号： No.51474064

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 矿业工程

项目作者： 王昭东

作者单位： 东北大学

项目金额： 90万元

中文摘要： 高强度高塑性是钢铁材料的重要发展方向，采用晶粒细化的方法是获得这种性能的有效途径。目前对纳米晶钢铁材料的制备和机理已经开展了深入的研究，然而纳米尺度条件下逆Hall-Petch关系和变形机制等关键性的科学问题仍有待于解决。本项目以Fe-Cr-Ni合金或中高锰钢为研究材料，提出采用形变诱导马氏体相变-退火奥氏体逆转变的创新工艺，通过对变形程度、退火温度和时间等参数的控制，制备出具有高强度高塑性的纳米晶钢铁材料（屈服强度800-1000MPa，伸长率30%-40%）。通过对纳米到亚微米系列晶粒尺寸材料的微观变形行为和孪生现象的研究，分析不同尺寸晶粒中位错属性与孪生、晶粒尺寸与孪晶体积分数之间的关系，揭示纳米晶变形过程不全位错的特性并论述孪晶对位错增殖的作用，阐明变形孪晶形核促进纳米晶材料应变速率敏感性的本质以及促进纳米晶材料塑性提高的变形机理。本项目的研究，对丰富纳米晶钢铁材料的强塑性理论具有重要的意义

中文关键词： 纳米结构；变形机制；逆转变；高强度；高塑性

英文摘要： There is a continued and significant interest to develop new generation of advanced steels with a high strength and high ductility combination for light-weight applications. Grain refinement is considered a potential approach to improve strength and ductility of engineering steels. Despite the excellent efforts, the understanding of inverse Hall-Petch relationship and deformation mechanism in nanograined structure continues to be unclear. In the context of obtaining high strength-high ductility combination, a novel processing route of developing nanograined/ultrafine-grained (NG/UFG) structure in metastable Fe-Cr-Ni alloy involving controlled phase reversion annealing of the cold deformed austenite has been developed in this proposal research. In this approach, severe deformation of metastable austenite at room temperature leads to strain-induced transformation of austenite to martensite. On annealing this severely deformed strain-induced martensite reverts back to austenite either via a martensitic shear or diffusional reversion mechanism. The phase reversion annealing sequence resulted in NG/UFG stainless steel that was characterized by a combination of ultrahigh yield strength and excellent elongation of 800-1000 MPa and 30%-40%. Utilizing the concept of phase reversion, the objective is to fundamentally understand grain size dependence on deformation mechanisms from NG to CG regime in a austenitic steel. The mechanistic contribution of twinning on strain hardening response and strain rate-sensitivity as a function of grain size, and the effectiveness of twinning in enhancing ductility of NG materials will also be studied in this proposed research. The proposed research provides a unique experience to researchers where physical metallurgy concepts will be introduced to develop NG materials, impacts the metals-related nanotechnology research being pursued.

英文关键词： Nanostructure;deformation mechanism;phase reversion;high strength;high ductility