Acoustic parameters as the material formability criteria

Two methods of non-destructive evaluation of material condition are presented in this paper. These methods are based on careful measurement of Rayleigh wave propagation velocity with a frequency of 5 MHz. Preliminarily investigations were carried out in order to relate the ultrasound propagation velocity to the mechanical characteristics of the deforming material. The first method allows estimating the strength limit by Rayleigh wave velocity measurement during elastic loading of the specimen. Since machine parts operate under elastic stress, this method can be used directly on working machine parts and frameworks. The second method is connected with the forming process and can be used for the definition of a criterion of elastic-plastic transition of metal products.