基于多物理场耦合的模具钢硬态切削表面层微观组织演变

The failure of the die and mold parts mostly occurs in the cavity surface; however the damages often begin in the range from tens of microns below the machined surface, which are all related to‘surface layer’under the machined surface. Therefore, as the outermost layer of the die and mold parts, the surface layer is an important component part of the surface quality. By means of integrating theoretical modeling, numerical simulation and experimental analysis, hard cutting process of AISI H13 die steel is determined as the research objective. Selecting the microstructure evolution in the machined surface layer of H13 steel as a starting point, the digital representation model about microstructures and performances in the machined surface layer based on the spatial scale and the mapping relationship between the macro-mechanical properties and the micro-zone mechanical properties are established respectively. By revealing the microstructure evolution mechanism in the machined surface layer under the coupling action of the thermo-mechanical-metallo fields, the evolution model about the microstructures in the machined surface layer with the combination of macro-simulation and micro-simulation is proposed, which can achieve a dynamic simulation and a quantitative prediction of microstructures and properties in the surface layer. Finally, based on the mapping relationship between the hard cutting process and the microstructures, and properties in the surface layer, the controllable evolution of the microstructures in the machined surface layer of H13 steel can be achieved by means of optimizing the hard cutting process. The implementation of this project is benefit to getting the specific microstructures, micro-zone properties and limited depth of the surface layer which can meet with the requirements of the macro-mechanical performances, and can promote the hard cutting process to jump from ‘shape controllability manufacturing’ to ‘shape-performance controllability manufacturing’.

模具失效大多发生于型腔表面，但破坏往往源自表面之下几十微米的范围内，都涉及到表面以下的“表面层”。因此，表面层作为模具的最表层，是模具表面质量的重要组成部分。通过理论建模、数值仿真和实验分析的结合，本项目选择 AISI H13模具钢硬态切削工艺作为研究对象，以切削表面层材料的微观组织演变为出发点，构建基于空间尺度的表面层微观组织与性能的数字化表征模型，建立宏观力学性能与微区力学性能之间的映射关系；通过揭示热—力—相变多物理场耦合作用下的表面层微观组织演变机理，建立宏、微观相结合的表面层微观组织演变模型，实现表面层微观组织及性能的动态模拟和定量预测；最后，基于硬态切削工艺与表面层微观组织及性能之间的映射关系，通过优化切削工艺，实现硬态切削表面层微观组织的可控性演变，获得满足宏观力学性能要求的特定微观组织、微区力学性能及表面层极限厚度，促使硬态切削由“控形制造”向“控形控性制造”跃升。

压铸模具的失效大多发生于型腔表面，但实际上许多破坏往往是从表面之下几十微米的范围内开始的，许多表面问题都涉及到表面以下的“表面层”。因此，为了保证压铸模具的长寿命和高可靠性使用，需要同时控制被加工零件的表面几何形貌特征以及表面层的冶金、物理、化学等变化两个方面。.本项目选择AISI H13模具钢硬态切削工艺作为研究对象，通过理论建模、数值仿真和实验分析的结合，主要完成了如下研究工作：① 适用于硬态切削的低温微量润滑条件下的油—气混合物流场雾化参数优化及内冷式刀具的切削性能评价。② 基于空间尺度的H13钢硬态切削切屑和切削表面层微观组织及性能数字化表征模型。③ H13钢硬态切削切屑和切削表面层的微观组织、性能演化机制和动态演化仿真。④ 模具钢五轴球头铣削三维表面形貌建模及加工表面缺陷分析。⑤ 面向特定力学性能和表面形貌要求的切削表面层状态的可控性演变。.结合研究成果，已在《International Journal of Mechanical Sciences》、《Materials Science & Engineering A》和《机械工程学报》等期刊上发表25篇论文。其中，应《航空制造技术》期刊邀请，以专稿形式发表综述论文“切削过程有限元仿真研究进展”。2019年12月，发表于《Journal of Manufacturing Processes》期刊上的论文“Simulated and experimental analysis on serrated chip formation for hard milling process”被全球著名科技媒体机构“工程进展”（Advances in Engineering，AIE）遴选为关键科学文章，对模具钢硬态切削机理研究进行重点报道。同时，申报了1项发明专利；培养了8名研究生，王鹏同学的毕业论文《汽车保险杠凹模加工表面形貌建模及数控加工仿真》被评为山东大学优秀硕士学位论文。以本项目所提出的球头铣削三维表面形貌模型为基础，与青岛海信模具有限公司签订了“模具高效加工关键技术”服务项目。通过优化切削参数组合，达到了提高加工效率、降低表面粗糙度值的目的，应用效果得到了企业的认可。.该项目的实施，实现了面向特定力学性能和表面形貌要求的切削表面层状态的可控性演变，促使硬态切削工艺由“控形制造”向“控形控性制造”的跃升。