关键词: 粉末冶金, 生坯加工, 边位印压, 裂纹扩展

Abstract: The green machining is an important approach for parts manufacturing of powder metallurgy，during which cracks and breakouts occur easily at the same time． The crack initiation and propagation behaviors of the green PM compacts subjected to edgeindentation are investigated to obtain the machined surface with high integrity． The results show that a crack initiates and spreads slowly along the indentation direction in a rectilinear form when the indentation load reaches a critical value． After that， the crack extends toward the outer surface of the specimen and eventually leading to the shedding of block materials encompassed by the crack． The crack is serrated in microlevel and forms a small angle with the indentation direction． Besides， the serrated crack does not penetrate into the machined surface． The crack propagation angle decreases with the increase of the interior angle of the indenter while remaining unchanged with the increase of the thickness of an indenter． The crack length increases significantly with the growth of the indentation thickness and increases as the growing of the interior angle of indenter when the interior angle is less than 70°，and then it barely changes with the angles that are larger than 70°． 

Key words: powder metallurgy, green machining, edgeindentation, crack propagation