奥氏体不锈钢中纳米孪晶的相变约束机制及尺度效应研究

项目名称： 奥氏体不锈钢中纳米孪晶的相变约束机制及尺度效应研究

项目编号： No.51271123

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 一般工业技术

项目作者： 陈爱英

作者单位： 上海理工大学

项目金额： 80万元

中文摘要： 超高强度奥氏体不锈钢是先进钢铁材料重点发展的结构材料之一。现有的强化方法存在高强低塑性和耐蚀性下降等问题，其中亚稳态奥氏体的马氏体相变是导致性能下降的直接原因。本项目在我们前期工作发现随着奥氏体不锈钢中孪晶尺度减小，马氏体相变受到抑制的基础上，探讨当奥氏体孪晶小于临界尺度时可能不发生马氏体相变的约束效应（不发生相变如纳米孪晶铜薄膜则并无此效应），小于临界尺度的孪晶则表现出其他变形尺度效应。拟利用高应变速率局域变形方法在体材料中制备出高密度纳米孪晶结构，系统研究奥氏体稳定性、应变速率和温度对微观结构演化和孪晶形成机制的影响。通过全面分析从亚微米到纳米尺度奥氏体孪晶的变形过程，探讨奥氏体孪晶独特的相变约束机制和变形尺度效应对材料强塑性机制的影响，以期全面揭示孪晶尺寸与相变的关系并为应用纳米孪晶机制优化奥氏体不锈钢性能奠定坚实的科学基础。

中文关键词： 奥氏体不锈钢；高应变速率；纳米孪晶；相变约束；强化机制

英文摘要： Ultrahigh-strength austenite stainless steel (SS) is one of the most important structural materials in the development of advanced iron and steels. However, the commonly used methods to strengthen austenite stainless steels often lead to irreconcilable compensations such as low ductility and degrading corrosion resistance, which may originate from deformation-induced martensite transformation from metastable austenite phase. In our previous work, this martensite transformation in the austenite stainless steel is remarkably suppressed with thickness of austenitic twins decreasing. Inspired by this thickness-dependent martensite suppression, this project aims at 1) a systematic investigation of a constrained martensite transformation (CMT) effect, viz. martensite transformation shall not occur on the condition of twin thickness lower than a critical size in austenite stainless steel(This thickness effect has not been observed in other nanotwinned materials such as Cu or Ag thin film since no martensite transformation takes place in these matrix materials when deformed). Due to the CMT effect, when the twin thickness is smaller than the critical size, some other mechanisms including multiple twinning, detwinning, or partial dislocation slip are expected to be the governing factor(s) in deformation; 2) exploring eff

英文关键词： Austenite stainless steel；steel;High strain rate；nanotwin；Constrained transformation；Strengthening mechanism