Change in Texture-Dependent Acoustic Birefringence in α-Fe and γ-Fe Polycrystalline Aggregates due to Plastic Deformation

This paper deals with the investigation of crystallographic texture evolution and the associated change in acoustic birefringence during plastic deformation under uniaxial tension of metal alloy. Results of computer simulation for orthotropic α-Fe and γ-Fe polycrystalline aggregates are compared with experimental data for different steels. The increment in acoustic birefringence of shear elastic waves caused by changes in the elastic properties due to plastic deformation is found to be positive for the α-Fe polycrystalline aggregate with a bcc lattice and negative for the γ-Fe one with a fcc lattice. This effect is concluded to be associated with the difference between bcc and fcc lattices, having different slip planes and slip directions. Scattering of initial orthotropic texture and critical shear stress are also found to affect the changes in the effective elastic properties and, accordingly, the quantitative increment in acoustic birefringence. The mentioned factors should be taken into account when assessing damage of metal alloy by the acoustic birefringence technique.