相间析出强化双相结构的组织性能控制机理研究

项目名称： 相间析出强化双相结构的组织性能控制机理研究

项目编号： No.51204048

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 冶金与矿业学科

项目作者： 贾涛

作者单位： 东北大学

项目金额： 25万元

中文摘要： 本课题提出一种独特的相间析出强化"铁素体+马氏体"双相结构，大量规则排列的相间析出碳化物使铁素体获得显著强化，一方面可降低铁素体与马氏体的强度差，另一方面通过应力传递，可促进马氏体的塑性行为，从而改善形变过程中两相应变的均匀性。这为解决高强双相钢在成形(弯曲和扩孔)中易于开裂的关键问题提供了一个新的思路。为此，拟采用实验与模型计算，研究相间析出碳化物形貌与相界上碳化物形核率、相界面迁移速度的关系，建立相间析出动力学理论模型；建立基于修正混合法则的拉伸应力-应变模型，研究铁素体/马氏体硬度比值、相比例对马氏体塑性行为的作用机理；确定成形性能与微观组织的内在联系，最终建立相间析出强化双相结构的组织、力学与成形性能的综合控制模型。本课题研究成果可为相间析出的精确控制提供关键性理论指导，可加深对微观组织与形变行为、断裂行为关系的理论认识，可用于指导高成形性高强热轧双相钢的开发，拓宽双相钢应用范围。

中文关键词： 相间析出；离散珠光体；双相；扩孔性能；相变动力学

英文摘要： A unique dual-phase structure composed of interphase precipitation strengthened "ferrite + martensite" is proposed in this research. The remarkable strengthening effect in ferrite, which is produced by the massive, orderly arranged interphase precipitated carbides, results in the improved strain uniformity between constituent phases during deformation due to the decreased strength difference between ferrite and martensite and the enhanced martensite plasticity. This provides a new idea to solve the crucial problem of fracture liability during forming process (bending and hole-expansion) of high-strength dual-phase steel. Therefore, experiments and model calculation will be employed to investigate the relation between the morphology of interphase precipitated carbides and nucleation rate of carbides on the phase interface, velocity of phase interface, and to build the theoretical model for interphase precipitation kinetics. Based on the modified law of mixtures, the stress-strain relation during tensile testing will be constructed. The mechanism by which the ferrite/martensite hardness ratio and the phase fraction affect the martensite plasticity will be studied. The internal link between formability and microstructure will be investigated. Eventually, the model for comprehensive control of microstructure, mechan

英文关键词： interphase precipitation；divorced pearlite；dual-phase；hole expansion；kinetics of phase transformation