织构化热处理显著提高金属接触表面服役寿命的强化机理及方法研究

For typical components such as wheel/rail, bearing and gears, their metallic contact surfaces suffer different types of wears when working in mixed rolling/sliding conditions, resulting in failure of the components and short service life. In this project, a structured heat treatment method using laminar plasma jet is proposed to obtain the structured functional surface, with emphasis on the strengthening mechanism for remarkably improving the service life of the metallic contact surface. The proposed method will be studied from the perspectives of the wear contact characteristics, the failure mechanism and the controlled preparation of the structured functional surface. The main scientific problems of this research are the failure mechanism of the structured functional surface in the mixed rolling/sliding conditions, how to design suitable structured functional surface for different contact load and how to precisely obtain the desired structure functional surface. Guided by these problems, the measurement and control of the heat flux distribution of the laminar plasma jet will be studied. Different plasma torches for generating laminar plasma jet with different range of heat flux distribution will be designed. An analytical model will be established for computing the distribution and change of the temperature of metallic contact surface during the structured heat treatment process, with which the final metallurgical structure will be predicted. The effect of the metallurgical structure and the shape & size of the fundamental types of structures, and the type of contact load on the contact wear characteristic of the structured functional surface will be revealed. Finally, criteria for designing the structured functional surface to remarkably improve the service life of the metallic contact surface will be formulated. In summary, the research in this proposal will provide us the theoretical basis and an implementation technique for improving the wear-resistance capability of the metallic contact surface in the key components and prolonging their service life.

针对铁路轮轨、轴承和齿轮等关键零件在滚滑接触复杂工况下，金属接触表面出现磨损和疲劳失效导致零件服役寿命短的问题，提出研究织构化热处理显著提高金属接触表面服役寿命的强化机理和基于层流等离子体束的织构化功能表面可控制备方法，从织构化功能表面的接触磨损特性、失效机理和可控制备方法等角度，以织构化功能表面在滚滑接触载荷作用下的失效机理、如何根据不同接触载荷类型设计织构化功能表面和如何可控制备所需织构化功能表面等关键科学问题为导向，研究层流等离子体束热流密度分布的表征和调控规律并开发能产生不同热流密度范围层流等离子体束的等离子体发生器，构建织构化热处理温度场变化计算模型和金相组织分布预测模型，明确基础织构的金相结构与几何形状及尺寸和接触载荷类型等对接触磨损性能的影响，构建能显著提高金属接触表面服役寿命的织构化功能表面设计准则。研究成果将为显著提高关键零件接触表面服役寿命提供一种理论依据和实施方法。

磨损和疲劳等失效会导致铁路轮轨、模具、轴承等关键金属零部件的服役寿命缩短，使得维护和更换频繁，直接增加了生产和运营成本。因此，本项目提出了一种基于层流等离子体束的织构化热处理技术并进行了系统研究，以提升金属接触表面的服役寿命。主要研究进展如下：（1）分析了层流等离子体电弧不稳定现象与射流特性，开发了织构化热处理的在线监测和诊断系统；（2）建立了织构化热处理的温度场仿真模型和金相组织预测模型；（3）揭示了织构化热处理的钢轨钢表面在滚滑接触载荷下的强化机理和失效机理；（4）通过层流等离子体束表面淬火提高了模具钢的耐磨性和耐腐蚀性；（5）通过“层流等离子体束表面淬火+刻蚀表面织构”改善了轴承钢的耐磨性；（6）提出了基于层流等离子体束的表面淬回火工艺，实现了主动调控硬化区金相结构和硬度分布，同时改善了钢轨钢在滚滑接触载荷下的耐磨性和接触疲劳抗性。本项目的研究成果可为改善金属接触表面的服役性能提供一种解决方案，并为织构化热处理技术改善金属表面服役寿命奠定了理论基础。