切削高强度结构钢形成的绝热剪切带微结构观察

Microstructure observation of adiabatic shear bands in cutting low alloy steel

使用扫描电子显微镜和透射电子显微镜对高强度结构钢30CrNi3MoV正交切削产生的切屑内绝热剪切带的微细组织进行了观察,测量了绝热剪切带的显微硬度.绝热剪切带中心和基体组织之间,组织是渐变的.绝热剪切带内硬度达到了淬火马氏体硬度,并具有细小的等轴晶组织,内部含有少量χ-Fe5C2和Fe3C碳化物与奥氏体.基体和剪切带之间的过渡区为大塑性变形的马氏体组织,分布有高密度的位错.研究结果表明,在实验切削条件下得到的绝热剪切带属于相变带.

The microstructure of adiabatic shear bands in the saw-tooth chips of low alloy steel 30CrNi_3MoV under orthogonal cutting conditions was observed by SEM and TEM. Microhardness measurement was performed on the adiabatic shear bands. The results show that the microstructure between the center of the shear band and matrix changes gradually. The average hardness value in the shear band reaches that of quenched martensite hardness. In the central region, the tiny equiaxed grains can be observed, the microstructure mainly consists of χ-Fe_5C_2, Fe_3C and small amount of austenite. In the transitional zone between the center of shear band and matrix, large deformed microstructure is observed and large amount of dislocations are found on the boundaries of the martensite laths. Investigative results show that the adiabatic shear bands presented in the test cutting conditions may be classified as transformed bands.