激光沉积大型镜面模具的型面完整性及界面可靠性调控机理研究

激光沉积成形技术为大尺寸高性能镜面模具设计和制造提供了新的技术途径。在普通模具钢基体上依次沉积中间层材料、高Cr马氏体不锈钢形成多材料梯度结构，既可兼顾高硬度、耐磨性、耐蚀性和整体塑韧性，又可保障大尺寸模具型面不同位置处组织、力学性能和镜面抛光性能均一。然而超精密机械抛光表面创成机理不明、缓冲层中原位组织转变及对性能/功能梯度影响机理不清晰，导致激光沉积技术在大尺寸高性能模具应用中严重受限。本项目通过揭示沉积态高Cr马氏体不锈钢的超精密机械抛光去除及损伤机制，形成型面完整性调控方法，并提出梯度缓冲层中成分梯度诱导原位组织转变机制与力热耦合约束下缓冲层成形新方法，解决大尺寸镜面模具高性能制造技术难题。

Laser metal deposition has become a novel technical approach for the design and manufacture of large-scale mirror mould with high performance. By depositing inter-layer materials and high-Cr martensitic stainless steel powders on the substrate of mould fabricated by traditional forming methods, the graded structure with multi-material was build. The higher hardness, abrasion resistance, corronsion resistance, and entire plasticity and toughness can be ensured, at the same time, the uniformity of microstructure, mechanical properties and mirror-surface polishing properties of large-scale mold surface can be realized. However, because of the absence of generating mechanism of ultra-precision mechanical polishing surface, the in-situ microstructrue transformation mechanism, and the influence of microstructure gradient on performance and functional gradient, the application of laser metal deposition process in large-scale mirror mould was critically limited. This project will put forward a controlling method of surface finishing by uncovering the mechanism of removal and damage by ultra-precision mechanical polishing, moreover, find the in-situ microstructrue transformation mechanism by composition gradient, and novel forming methods of interficial buffer layer under the restraint of thermal and mechanical load. As a result, the technical problem of high performance manufacturing large-scale mirror mould could be resolved in reasonable method.