高强度纳米贝氏体钢的疲劳特性及失效机理的研究

项目名称： 高强度纳米贝氏体钢的疲劳特性及失效机理的研究

项目编号： No.51301033

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 一般工业技术

项目作者： 杨静

作者单位： 东北大学

项目金额： 25万元

中文摘要： 高强度纳米贝氏体钢具有几十纳米厚板条贝氏体铁素体和其间薄膜残余奥氏体组织，常规力学性能接近马氏体时效钢的水平，并在高性能传动轴、轴承、齿轮、铁路钢轨、辙叉及装甲钢板等重要零部件的制造有应用前景。但与使用性能密切相关的疲劳行为的研究还没有系统深入开展，特别是组织对高周疲劳性能的影响及疲劳损伤的组织作用机理还未进行研究。申请者初步研究发现，高强度纳米贝氏体钢的疲劳极限不随抗拉强度单调升高，而是与残余奥氏体有着密切的联系，这一现象与传统金属疲劳理论不一致。故本项目拟采用轴向拉-拉高周疲劳试验方法，研究高强度纳米贝氏体钢在高周循环应力作用下及疲劳裂纹扩展过程中微观组织演变规律，疲劳裂纹扩展途径，以及微观组织对疲劳性能的影响规律，从而揭示高强度纳米贝氏体钢高周疲劳行为与组织作用机理，以及提高疲劳性能的组织控制因素。这不仅可丰富钢的疲劳断裂理论，也可为高强度纳米贝氏体钢的应用提供参考。

中文关键词： 纳米贝氏体钢；微观组织；力学性能；疲劳性能；断裂机制

英文摘要： High strength nanobainitic steels composed of tens nanometers thick lath-like bainitic ferrite and film-like retained austenite have mechanical properties close to the level of maraging steels. They are potentially used for the manufacture of high-performance shafts, bearings, gears, rails, crossings and armours. However, high-cycle fatigue behavior which is intimately related to the service performance, especially the effect of microstructure on high-cycle fatigue property and microstructural action mechanism of the fatigue damage have not been studied deeply. Our primary work shows that the bending fatigue limit of the high strength nanobainitic steel is not monotonically increased with the utimate tensile strength, but is related to retained austenite. This phenomenon is not consistent with the conventional metals fatigue theory. Therefore, this work is to study the microstructural evolution during the stress cycle and the crack propagation, and the crack propagation route by axial tension to tension high-cycle fatigue test, and to study the effect of microstructure on the fatigue property, in order to explore the high-cycle fatigue behavior and microstructural action mechanism of high strength nanobainitic steel, and microstructural controlling factors to enhance the fatigue property. This study will not onl

英文关键词： Nanobainitic steel；Microstructure；Mechanical properties；fatigue properties；Fracture mechanism