Continuous Measurement of Residual Stress in Thin Cylindrical Pieces Using Deflection-Etching Techniques

Authors: A. Decneut, J. Peeters

Abstract

With the development of continuous layer removal techniques, the deflection-etching method has demonstrated a degree of refinement and precision, making it suitable for the study of grinding stresses which are extremely shallow and have severe gradients. Several investigators already use this method for residual stress measurements in flat shaped pieces. In order to control residual stresses in cylindrical pieces, the Research Center of the Belgian Metal Working Industry (CRIF) developed an appropriate continuous deflection-etching technique. Throughout the design of the test set-up, special care was taken to obtain a maximum sensitivity and accuracy, e.g. measurements are performed on half a cylinder which is giving much larger deformations than the complete ring. The classical deformation measurement in the middle of the test piece is replaced by a relative deformation measurement of one end to the other. The great benefit is an increased sensitivity with a factor 3.5. The paper gives the corresponding equation which replaces the equation developed by J. Frisch and E.G. Thompson for flat pieces. The test equipment and practical procedure are described. The reproducibility of the method is checked and some typical stress plots are discussed. The results appear to be very consistent.