热锻模具激光再制造熔覆层材料-组织-性能调控机理

Dies and molds are fundamental process equipments in industrial production. Hot forging dies are always working in conditions of long-term high temperature, high pressure and alternating loads, and are liable to damage and failure in forms of abrasion, plastic deformation, thermal fatigue and so on. Because of the characteristics of higher power density, better bonding strength of the interface, smaller heat affected zone and better flexibility, laser cladding technology will have a wide application prospect in the field of hot forging die remanufacturing. According to the key scientific problems exist in this field, adjustment and control mechanics between materials, microstructure and properties of remanufactured hot forging die remanufacturing cladding layers will be studied. Matching design principles and methods of heterostructure/gradient materials of the cladding layers will be illustrated. Influences of characteristics of the heat affected zone and the substrate and the heat treatment regime on the microstructure and properties of the remanufactured components will be studied. And the evolution behavior and mechanism of the microstructure in the material interface will be revealed. Through the coupled numerical simulation of the temperature and force fields, measurement and control of the key parameters in the forming process and evaluation and characterization of the comprehensive properties, optimal tailored and customized methods among materials, microstructure and properties at certain locations of the cladding layers will be explored to enhance the remanufacturing quality and service performance of the hot forging dies, which will provide a theoretical basis for the propagation and application of the laser cladding remanufacture technology of hot forging dies. The research results will also provide references for the forming and remanufacturing of other hot working dies such as pressure-casting dies, hot extrusion dies and so on. The theory and connotation of remanufacture can be enriched and developed, and it will have important scientific values and better social and economic benefits.

模具是工业生产的基础工艺装备，热锻模具长期在高温高压和交变载荷下工作，极易造成磨损、塑性变形及热疲劳等损伤和失效。由于具有功率密度高、界面结合强度好、热影响区小、柔性高等特点，激光熔覆技术在热锻模具再制造领域应用前景广阔。针对该领域存在的关键科学问题，本项目拟开展热锻模具再制造熔覆层材料-组织-性能调控机理研究，阐明熔覆层异质/梯度材料成分匹配设计原理和方法；研究热影响区、基体特性及热处理制度等对再制造零件组织性能的影响；揭示材料界面组织演化行为和机理。通过热力耦合数值模拟、成形过程重要参量检测与控制及综合性能评价与表征，探索熔覆层特定部位材料-组织-性能最佳裁剪和定制方法，提升热锻模具再制造质量和服役性能，为热锻模具激光熔覆再制造技术的推广应用奠定理论基础，也可为压铸模和热挤压模等其他热作模具成形和再制造提供参考，丰富和发展再制造理论与内涵，具有重要的科学价值和社会经济效益。

热锻模具在高温高压等工作环境中极易产生磨损、变形、开裂等形式的失效，激光熔覆是一种有效的表面改性和再制造方法。然而，由于激光熔覆加热及冷却速度极快，使得成形过程温度梯度及冷却速率很大，易导致涂层开裂。本项目以H13热锻模具材料为研究对象，采用理论分析、有限元数值模拟和试验研究相结合的方法，研究了H13热锻模具钢表面梯度复合涂层的激光熔覆成形方法，探索了梯度复合材料的优化匹配设计原理和方法，进行了工艺参数优化，阐明了材料的界面行为、组织特性及熔覆层显微组织演化机理；采用热力耦合数值模拟方法，研究了激光熔覆梯度复合涂层工艺参数对温度场及应力场的影响，获得了温度场、应力场分布，以及温度梯度、冷却速率及残余应力的变化情况；对H13钢表面激光熔覆梯度复合涂层组织性能及开裂行为进行了研究，揭示了熔覆层表面开裂机理，并对裂纹控制方法进行了初步探索；开发了激光熔覆熔池形貌检测系统，研究了H13钢表面激光熔覆时，工艺参数变化对熔池形貌和熔覆带质量的影响规律，获得了具有稳定熔池的工艺条件；采用设计的材料及优化的工艺参数，对失效的H13钢模具进行了再制造。项目研究结果为H13钢及热锻模具激光熔覆再制造技术的推广应用，探索热锻模具特定部位材料-组织-性能一体化调控方法提供了参考依据，对提升热作模具及其他机械零件再制造质量和服役性能具有一定的工程应用价值和社会经济效益。