高能激光处理合金钢非平衡离子渗氮层强韧机理

The development and manufacturing of the spacecraft in China are rapidly growing, the technologies for key parts manufacturing to ensure the life and reliability of aerospace product are needed urgently. In the conventional carburizing and nitriding, the phase transition and precipitation occurred in surface layer enhance its strength, and at the same time is also along with an increase of brittleness and an decrease of corrosion resistance. There is no core technology of preparation the surface super high strength and toughness and wear modified layer, especially for aerospace products. This application focuses on the design and characterization of non-equilibrium organizations of the surface of alloy steel, including the high energy laser processing pretreatment method, and the microstructure evolution of non-equilibrium hardened surface layer. The microstructure evolution and mechanical properties characterization of non-equilibrium plasma nitriding layer for alloy steel will be researched, getting the thermal diffusion kinetics and element distribution of non-equilibrium surface plasma nitriding layer. A new modified layer based on the non-equilibrium plasma nitriding layer is prepared by high energy semiconductor laser treating. The microstructure evolution, mechanical properties and wear resistance of the modified layer will be analyzed, revealing the strengthening and toughening mechanism of the modified layer. Then the modified layer with large thickness, high strength, high toughness and wear resistance can be prepared for alloy steel of the aerospace products. This technology which expands the surface modification methods for key parts will support the manufacturing of key components of the aerospace products. The researches above are of significance to theoretical studies and engineering applications.

我国航天器的研发与制造进入快速发展时代，对确保产品寿命和可靠性的关键零部件的制造技术需求更为迫切。常规渗碳、渗氮层强化机制源于相变和析出相，渗层脆性高、耐蚀性差。表面超高强韧与耐磨改性层制备目前还没有形成核心表面改性技术，尤其航天产品缺乏大厚度超高强韧表面改性层制备方法。本次申请聚焦在合金钢表面非平衡组织设计及表征，包括高能激光处理材料表面获得非平衡组织的预处理方法、非平衡硬化层组织结构演变研究；合金钢非平衡组织等离子体渗氮层组织结构演变及性能分析，获得非平衡组织离子渗氮过程渗入动力学及元素分布；利用高能半导体激光在非平衡离子渗氮层基体上制备新型改性层，研究其微观组织结构演变、力学性能及耐磨性变化，揭示改性层强韧化机理，在航天产品常用合金钢表面制备大厚度高强韧耐磨改性层，扩展航天产品关键部件表面改性方法，支撑我国航天产品关键基础零部件制造，具有理论研究意义和实际应用价值。

针对航天器与武器系统常用经济中碳低合金钢材料，开展表面非平衡组织设计及表征，包括高能激光处理材料表面获得非平衡组织的预处理方法、非平衡硬化层组织结构演变过程研究，利用金相组织观察（OM）、扫描电子显微镜观察（SEM）及能谱分析（EDS）、透射电子显微镜观察（TEM）等分析测试方法研究了各状态改性层的组织结构、力学性能、耐磨性及耐腐蚀性能的影响。.利用新型半导体激光淬火装备制备大厚度表面硬化层，获得非平衡组织演变过程及硬化层硬度、耐磨性能，揭示大厚度激光硬化层强化机制，重点在高能激光扫描材料表面形成细小马氏体，支撑表层强化。.通过合金钢非平衡组织等离子体渗氮层组织结构演变及性能分析，获得非平衡组织离子渗氮过程渗入动力学及元素分布；研究其微观组织结构演变、力学性能及耐磨性变化，揭示改性层强韧化机理。.在中碳低合金钢表面利用高能激光扫描浅层离子渗氮层制备复合改性层，离子渗氮与激光淬火复合处理降低了材料的摩擦系数，显著提高了材料耐磨性。未处理试样的磨损机制主要是以粘着磨损为主，局部有塑性变形，伴随着表面疲劳及氧化；试验载荷的大小并不改变磨损机制，只影响磨损程度；改性层的主要磨损机制均为程度不一的粘着磨损，没有较大塑性变形。.本项目研究成果可以为航天飞行器产品中耐磨结构件表层制备耐磨改性层、武器型号大量合金钢运动构件表层强化耐蚀等提供技术方法，扩展航天产品关键部件表面改性方法，支撑我国航天产品关键基础零部件制造，具有一定的实际应用价值。.