金属材料在振动切削时脆化机理的研究

振动切削实质是一种高能量冲击切削。位错、挛晶、微晶和亚晶粒组织是高能冲击切削时金属材料的主要组织形态，高密度变形条带相互交叉、阻滞或截割，使晶体组织严重细化为微晶，同时发生严重的点阵畸变，使晶体的自由能升高，金属材料的强度硬度升高，同时塑性韧性下降。特别是在高速、高能量冲击载荷的作用下，变形区内主要组织形态是孪晶和亚晶粒，材料的塑性和韧性降低，脆性大幅增加。切削时，呈现脆性分离形成的崩碎切屑。

Study on Mechanisms of Metal Material Brittleness under Vibration Cutting

Vibration cutting is a high energy impact cutting in substance. Dislocation, twin, nano-sized grain and subgrain are main morphologies of cutting surface of metal material because of deformation under high energy impact. Intersecting,, blocking, cutting each other of deformation bands with high density cause serious fragment of grain which become twin and nano-sized grain , besides, distortion of lattice which raises the free energy of crystal and strength and harden of the metal are risen. Especially, under high velocity and high energy impact, main morphologies are twin and subgrain in deformation region, so that plasticity and toughness descend, brittleness is risen greatly in deformation region. Cracking cutlet is formed because of brittle separation.