Propagation of acoustic waves during the control of hydrogen-induced destruction of metals by the acoustoelastic effect

The evolution of velocities of ultrasonic waves, acoustic anisotropy and damage in the case of inelastic deformations of structures up to large plastic deformations was investigated using the method of acoustodamage. A correlation between distributions of acoustic anisotropy and distributions of hydrogen concentrations was experimentally established. Relationships between the principal values of the damage tensor and velocities of acoustic waves were obtained. The comparison of three schemes of symmetrization of the effective stress tensor in the case of inelastic uniaxial step loading of specimens from commercial alloys established that the use of implicit additive scheme gives the most conservative estimates of damage. Analysis of extreme values of the experimental angular diagrams of the acoustic anisotropy and velocities of transverse waves allowed one to define the orientation of directions of principal axes of stress tensor without unloading the structure. The results of investigation has a great importance for nondestructive acoustic control of structural elements with undefined orientation of directions of the principal axes of stress tensor.