磨削剥离裂纹的产生机理与特征

Mechanism and Characteristic of Grinding Peeling Crack

磨削剥离裂纹产生的原因为:当磨削变质层的深度达数个毫米时,在深度方向上磨削变质层和零件基体正常组织之间的应力显著增大,受此应力叠加作用的影响,当磨削裂纹在表面最大拉应力处产生并扩展到一定深度后,最大拉应力的最大方向从原来水平方向逐渐向垂直方向偏转,使裂纹沿着水平方向扩展,当达到变质区的边界时受表面变质区收缩拉应力的影响,再扩展到表面,形成磨削剥离裂纹,并在裂纹末端伴随有明显的锯齿特征。

The causes of grinding peeling crack are as follows:when the depth of grinding affected layer reaches several millimeters,the stress between grinding affected layer and normal structure of part matrix increases remarkably in depth direction;influenced by superposition function of stress,when the grinding crack generated on surface by maximum tensile stress and propagated to a certain depth,the direction of maximum tensile stress deflects from original horizontal direction to vertical direction gradually,and the crack propagates along horizontal direction;when reaching to boundary of grinding affected zone,the crack is affected by shrinkage tensile stress of surface affected zone,and then propagates to surface,forming grinding peeling crack,and the crack end is accompanied by obvious serration characteristic.