硬脆颗粒增强金属基复合材料的切屑形成机理

THE CHIP FORMATION MECHANISM OF HARD PARTICLE REINFORCED METAL MATRIX COMPOSITES

颗粒增强金属基复合材料具有非均匀的显微组织结构，在切削力作用下其剪切变形不是在一个平面内而是在一个有相当厚度的区域内完成，传统的单一剪切平面模型不适合用于这类非连续增强型复合材料的切削分析．颗粒增强复合材料基体的塑性变形始终受到不可塑性变形颗粒的干扰，故在复合材料成屑过程中裂纹的形成和扩展起重要作用，并由此决定了切屑的基本形态．分析了材料进入剪切变形区后发生的非定向连续滑移、剪断和基本稳定滑移三种情况．

Particle_reinforced metal matrix composites have a non-uniform micro constructure. Under the cutting force their shear deformation takes place not within a plane but in a region which has a certain thickness, so classical cutting model based on single shear plane is not suitable for analyzing the cutting of this kind of composites. The reinforcing particle which is not enabled to plastically deform always interferes with the plastic deformation of matrix of the composite. Consequently,the formation and propagation of crack play a important role during the chipping process, which controls the essential form of chip. Then three circumstances after the composites enter the shear deformation region are analyzed:consecutive but non_directional slip, shear break and basically stable slip.