Influence of the Metal Structure and Plastic Deformation on the Nonlinear Acoustic Parameter

A practical task of testing samples of various metals using the principles of nonlinear acoustics is being solved. A surface acoustic wave (surfactant), whose propagation process, due to nonlinear effects, is accompanied by generation of a wave of doubled frequency, was used for testing. An experimental device is used to monitor the structural state of a metal sample by recording a change in the nonlinear acoustic parameter (NAP). To excite surfactants, a wedge transducer with a resonance frequency of 1 MHz was used. The transmitted wave was recorded with a wedge transducer with a resonance frequency of 2 MHz. It has been shown that the NAP for the tested materials in the initial state has different values not only for materials belonging to different classes, but also for materials belonging to the same structural class and having different chemical compositions (12Kh17G9AN4 and 12Kh18N10Т). A plastic deformation by 2% does not lead to a NAP change for the AMg6 alloy and 12Kh17G9AN4, 20Kh13N4G9, and 10KhSND steels. The NAP change by 2% as a result of a plastic deformation for the 12Kh18N10T and 08Kh17N4M3 stainless steels is caused by a change in their phase compositions associated with the martensitic transformation. The presented data on the change in the NAP from early stages of the elastoplastic deformation to a predestruction for AMg6 and 10KhSND steels demonstrate the possibility of using it as a prognostic criterion for the limiting state of the material.