DETERMINING THE EVOLUTION OF THE ELASTICITY MODULUS BY SURFACE-WAVES ACCORDING TO THE DEPTH IN A NITRIDED LAYER

Measuring the variation of the elasticity modulus as a function of dep th in nitrided layers requires that the analysed material and surface wave propagation be perfectly known. The present work consists in deve loping a non-destructive method that uses wide bandwidth ultrasonic tr ansducers, aimed at determining the evolution of the elasticity modulu s as a function of z. The results currently obtained show that the wav e propagation velocity as well as the elasticity modulus are subjected to minor evolutions in the nitrided layers and that the variations of the density and the residual stresses have a significant effect on me asures and calculations.