TRIP型汽车钢亚稳奥氏体含量及其稳定性与强度塑性间定量关系研究

The TRIP typed automobile steels with different austenite fraction and austenite stability, including conventional TRIP steel, Q&P steel and the medium-Mn,have been developed over the last three decades. Even though the austenite fraction and its stability are thought to be the decicive parameters to the mechanical properties of the TRIP typed steels, few quantitative relationship between the mechanical properties and the microstructure had been reported, which limits the further research and application of these automobile steels. Thus it is proposed in this project that the relationship between mechanical properties and the microstructural parameters will be studied for the TRIP typed steels with different typed matrix， different austenite fraction and different austenite stability. To get to this target, the type of the matrix，austenite volume fraction and its stability will be characterized by the advanced techniques, such as the X-rays diffraction(XRD), electron back scattered diffraction patterns (EBSD) and In situ Neutron Diffraction (ISND), and the mechanical properties will be measured accurately. At the last, the quantitative relationship between strength/ductility and the volume fraction/stability of the austenite will be built based on the theoretical reasoning of the strain induced phase transformation and the analysis of the experimental data.

历经30年快速发展，目前已形成传统TRIP钢、Q&P钢和中锰钢等具有不同亚稳奥氏体含量与不同奥氏体稳定性的TRIP型汽车钢。奥氏体含量与奥氏体稳定性是决定TRIP型汽车钢力学性能的关键参数，但目前仍然没有有关TRIP型汽车钢的力学性能与微观组织结构参数间定量关系的研究结果。因此本项目提出从实验与理论等两个层次，对不同基体类型、不同奥氏体含量及不同奥氏体稳定性TRIP型汽车钢的力学性能与微观组织结构间的关系进行系统定量研究。利用X-射线衍射、背散射电子取向成像和原位中子衍射等先进组织结构表征技术和各种力学测试手段精细分析基体相类型、亚稳奥氏体含量及稳定性，准确表征钢的力学性能。本研究计划在分析亚稳奥氏体形变诱发相变机理的基础上，进行大量实验数据分析与回归，最终建立TRIP型汽车钢的强度和塑性与钢中亚稳奥氏含量与稳定性间的定量关系，为解决TRIP型汽车钢的强韧化提供理论支持和实验依据。

TRIP型高强塑积汽车钢的需求与理论研究得到了国内外的高度关注，成为近10年国内外研发热点。本项目对不同基体类型(铁素体基体、马氏体基体和贝氏体基体)和不同奥氏体特性(奥氏体含量、奥氏体稳定性)的TRIP型汽车钢的合金化、组织性能调控以及结构与性能关系进行了系统定量研究，探索TRIP型汽车钢的塑性与钢中亚稳奥氏体特性之间的定量关系。结果表明，通过中锰合金化钢的逆相变研究，形成了可工业化的30GPa%的高强塑积汽车钢技术及其理论，为中锰第三代汽车钢的工业化与研发奠定了理论与实验基础；通过中锰钢的高温动态相变行为研究，开发出可工业化的高应变速率和1000%高延伸率的冷轧低中碳超塑性钢，打破了低中碳钢不具有超塑性和工业化低中碳钢不具有超塑性的局面；通过中锰钢的微观组织结构调控，形成了具有450J冲击韧性的热轧双相复合高强高韧性钢，为高强和高韧性钢的研发开辟出复合强韧化的研究方向。本项目研发成果为中锰第三代汽车钢、超塑性低中碳钢和高强韧双相层片钢的工业化奠定了理论和试验基础，得到了国内外广泛关注。本研究成果发表了包括2篇Scientific Reports的21篇SCI论文、论文总数35篇、发明专利4项和省部级科学技术进步一等奖3项。