预处理方式对工件表面残余应力的影响研究

Pretreatment Influence on Surface Residual Stress of Work Piece

预处理方法对表面残余应力测试结果有着重要影响。采用不同目数的手工砂纸、机械布砂轮、机械砂轮、电解抛光等表面处理方式对同一材料表面不同区域进行了处理,利用X射线法测试了各区域残余应力。结果表明,打磨过的试样随着腐蚀深度的增加,表面残余应力由压应力不断向零逼近,并在达到250微米深度时变化幅度明显减小,转化为正应力,在达到300微米时,其残余应力接近原始残余应力值。各种预处理方式引入的表面附加应力差异较大。因此,针对表面残余应力测试,相对最为合理的预处理方式是45度交叉布砂轮打磨之后,再采用电解腐蚀去除加工应力层。

The pretreatment methods have great influence on the surface residual stress data. Difference pretreatment methods include hand sanding, fabric machine sanding, grinding and electro-polishing are used on different parts of one specimen. The surface residual stress of different regions is tested by X-ray. The result shows that when polishing deepness increases, the residual stress of the fabric machine sanding parts infinitely approximates zero. The residual stress becomes positive and is close to the original value when polishing deepness researches 250μm and 300μm respectively. The additional surface stresses introduced by different pretreatment are discrepant. The comparatively appropriate pretreatment of surface residual stress test is to use crosswise fabric machine sanding with 45 degree, then remove the machining stress layer with electrolytic polishing.