Non-Destructive Testing of the Residual Stress Profile After Shot Peening by Multifrequency-Eddy-Durrent Analysis

Author:  Renaud Frappier, Yvan Bordiec
Source:  ICSP-13
Doc ID:  2017076
Year of Publication:  2017
Abstract:  
Introduction: Residual stress (RS) testing after shot peening (SP) is an issue of high industrial interest. A reliable test has to quantify the imparted residual stress: superficial RS, subsurface maximal RS and total affected depth by SP. The most common testing methods are: incremental X-ray diffraction (XRD) with material layer removal, and incremental strain gage hole drilling. Both are destructive and usually implemented as off-line test because of long time measurement (one hour to one day). For non-destructive testing (NDT) of RS, the opportunity to apply conventional ultrasonic or magnetic methods was identified. For instance, multi-frequency eddy current (EC) testing appears as a promising tool since the penetration depth is dependent to the applied test frequency, and the residual stress can be correlated to EC test results (measured coil electrical impedance or calculated apparent conductivity of the material under investigation) [1][2].