An Ultrasonic Study on Variations of Elastic Anisotropy with Plastic Compression

Abstract

Measurements of ultrasonic transverse waves were made in order to investigate the development of elastic anisotropy of a polycrystalline metal with plastic deformation. From the same bar of S18C steel, specimens were prepared so that the velocities v₁ and v₂ of two polarized transverse waves could be measured for several values of the compressive plastic strain e along the bar axis, and of the angle θ of the direction of propagation from the axis. The results show that the anisotropy of the material is composed of the initial transverse isotropy and the transverse isotropy developed in proportion to the compressive plastic strain, and that these are nearly equal in type, but opposite in sign. It is also shown that the elastic anisotropy thus determined is not coincident with that derived from the Voigt model of a polycrystalline material, but that the difference between them is of allowable degree.