Near surface residual stress detection of metallic materials using the high order ultrasonic nonlinear coefficient

Abstract

Because residual stress seriously affects the mechanical properties of metallic components, in the study the nonlinear property of LCR wave is studied and the near surface residual stress within a certain depth beneath the component surface is nondestructively detected for the safe service of metal components. The stress detection system based on LCR wave is constructed using the oblique incident method with one-in-one-out mode. The high order relative nonlinear coefficients, β′ and δ′, during 45 steel tensile process are measured to investigate the correlation between nonlinear property of ultrasonic and stress. Two pairs of relative nonlinear coefficients monotonically increase and the stress sensitivity of δ′ is better than β′. In order to eliminate the sensitivity difference, the comprehensive nonlinear parameter is proposed. Three stress detection models based on experimental data are established and the error of residual stress evaluation are all below 4%, this indicates the nonlinear characteristics of LCR wave can be used to detect the stress level within a certain depth beneath the component surface. So the high-order ultrasonic nonlinear coefficients of LCR wave provides an effective method of rapid non-destructive detection the near surface residual stress of metallic material.