Effect of surface roughness on the results of residual stress measurement

Spherical indentation strain-gauge method is one of methods to measure the surfaced residual stress with measurement depth of 0.1 mm.The impact of surface roughness on residual stress results was discussed.The results have shown that,in tests（1）and（2）,R_x is dropped by 14 MPa approximately with the surface roughness being decreased from 0.75μm to 0.55μm.While in tests（3） and（4）,R_x decreases about 44 MPa with the surface roughness being decreased from 0.75μm to 0.55μm.Compared to tests（1） and（2）,the effect of the surface roughness on residual stress results is more significant in tests（3） and（4）,and the reduction effect of surface roughness on residual stress measurement is enhanced.In engineering application,most components are already in different stress states.Therefore,the influence of surface roughness on residual stress measurement can not be ignored.Residual stress of a 2219-T87 Al alloy plate was measured.With the confidence level of 0.95,the confidence interval is-122.515,-113.884 9MPa.