CADI磨球表层残余应力的测定

Measurement of Residual Stress on Surface of CADI Grinding Balls

基于弹塑性平面应力和残余应力的相关理论,利用电测技术和“切割法”对CADI磨球碰撞前、后表层的残余应力进行了测定,对磨球表层的残余应力有了定量认识。测试结果表明,经过多次落球试验碰撞的CADI磨球表层,存在着约500~900MPa、各方向基本相等的环向压应力,残余应力数值随着碰撞次数的增加而增加,但超过20000次后增加并不明显;碰撞磨球表层的残余应力数值与Mn含量存在着正相关关系,在某一范围内,Mn含量越高,残余应力越大;未经碰撞的CADI磨球表层也存在着拉伸(或压缩)环向残余应力,但其数值都比碰撞后磨球的残余应力小得多。

Based on the theories of elasto-plastic plane stress analysis and residual stress analysis,electrical measurement technique and the cutting method were used to measure the residual stress on the surfaces of CADI grinding balls impacted and un-impacted.Quantitative understanding was obtained for the residual stress on the surface of CADI grinding balls.The measurement results show that there exists circumferential residual compressive stress about 500-900 MPa,approximately equal in all directions on the surfaces of randomly impacted CADI grinding balls.The value of residual stress increases with the time of impacting.But the increase tendency slows down after 20000 times impacting.A positive correlation is found between the residual stress and the content of manganese.Within a certain extent,the higher the content of manganese is,the bigger the residual stress on the surface of CADI grinding ball will be.Tensile(or compressive)residual stresses were also found on the surfaces of un-impacted grinding balls,but their values are much smaller than those of impacted grinding balls.These findings might have reference significance for designs of the material of CADI grinding balls and heating treatment technology.