旋回破碎机4Cr13钢主轴套激光淬火后的磨削裂纹分析

旋回破碎机4Cr13钢主轴套在激光淬火后磨削阶段发现多处裂纹,且与外圆轴向呈约15°夹角。通过宏观分析、化学成分分析、硬度、有效淬硬层深度检测及显微组织观察等,确认了4Cr13钢主轴套裂纹为磨削裂纹。裂纹的产生主要是由于砂轮磨削过程中存在切向与轴向两个方向的运动,切向转速远大于轴向移动速度,两个方向产生的磨削拉应力合力造成裂纹与轴向呈约15°的夹角。同时,激光熔凝产生的放射状柱状晶降低了晶体间的结合力,加之采用激光淬火余温自回火的方式,使淬硬层应力分布较复杂,使其在磨削过程中易出现裂纹。

Analysis of grinding cracks on 4Cr13 steel spindle sleeve for gyratory crusher after laser quenching

Several cracks were found in the grinding stage of the 4Cr13 steel spindle sleeve for gyratory crusher after laser quenching, and having angles about 15° with the outer circle axis. Through macroscopic analysis, chemical composition analysis, hardness, effective hardened layer depth detection and microstructure observation, it is confirmed that the cracks of the 4Cr13 steel spindle sleeve are grinding crack. The cracks are mainly caused by the movement of tangential and axial directions in the grinding process of the grinding wheel. The tangential rotation speed is far greater than the axial moving speed. The resultant force of grinding tensile stress in the two directions results in an angle of about 15° between the crack and the axial direction. At the same time, the radial columnar crystal produced by laser melting reduces the bonding force between crystals. In addition, the residual temperature self-tempering method after laser quenching makes the stress distribution of hardened layer more complex, which makes it easy to crack in the grinding process.