脆性材料延韧精磨表层多维物理性能强化机理

延韧精磨既能提高脆性零件表面精度，又能增强其表层强度/塑性/韧性，是脆性零件获得优越抗疲劳性能的有效技术途径，也是实现精密零件控形-控性的科学机制。课题针对大型典型脆性零件的服役性能需求，探索脆性材料延韧精磨表层多维物理性能形成和耦合强化机理。理论上，精磨表层形成的静水压应力能使脆性材料在延韧域去除，可避免磨削表层脆性破裂，有利于形成细化晶粒、残余压应力和位错增殖。研究拟耦合脆性材料本构方程，脆韧转换机理、单磨粒的摩擦-滚压-犁削-切削模型、多磨粒层次关联方程、高效磨削理论、多尺度性能仿真与测试技术，探索微磨粒和磨削控制参数与磨削表层塑性-强度-韧性等多维物理性能的映射关系，建立以精磨表层性能强化为目标的脆性零件多维物理性能预测和控制模型，克服磨削诱发的零件表层热损伤、相变和裂纹萌生扩展。基于实验实证、参数敏感度分析和抗疲劳性能评估，获得脆性材料高效延韧精磨表层物理性能强化的科学控制方法。

Ductile finishing grinding can not only improve the surface finish and geometric accuracy of brittle parts, but also enhance their surface strength, plasticity and toughness. It is an effective technical approach to achieve superior fatigue resistance performance of brittle parts, and it is also a scientific mechanism to acquire "multi-controlling of geometrical and physical properties" of brittle parts generated from finishing grinding. Based on the service performance requirements of typical large-scale brittle parts, the project intends to explore the formation of multi-physical properties and the coupling strengthening mechanism on the machined surface of brittle materials subjected to ductile finishing grinding. In theory, the machined surface layer of brittle parts can produce hydrostatic triaxial-compressive stress field to remove brittle material in ductile region, therefore it helps avoid the brittle fracture of the surface layer, favorable for grain refinement, dislocation multiplication and compressive residual stress formation. In this study, the constitutive equations of typical brittle materials, brittle ductile transition mechanism, single abrasive grinding-abrasives distribution hierarchical association multi-model, high-speed grinding theory and multi-scale performance testing technology are coupled to explore the formation mechanism of multi- physical properties of brittle materials, such as hydrostatic triaxial-compression, grain refinement, dislocation multiplication, and establish the surface performance enhancement by finishing grinding process as the main objective. The predictive controlling model of the surface integrity of the brittle parts enable to overcome the surface thermal damage, material transformation and crack initiation and propagation induced by high efficiency grinding of brittle components. Based on the experimental validation, parameter sensitivity analysis and fatigue resistance evaluation, this research will explore the scientific control method for the surface performance enhancement of brittle materials generated from high-efficiency ductile finishing grinding.