Does plastic anisotropy affect the thermo-mechanical coupling in steel?

The Taylor-Quinney coefficient (TQC) quantifies the ratio of thermal to plastic work in a (dynamically) deforming specimen. Its importance lies in the determination of the material self -heating under shock which might influence the properties of the materials. Most work to date is based on isotropically deforming specimens, so that the determined global quantities exhibit no spatial variation or anisotropy. Even the few existing works on anisotropic material were carried out using an average stress-strain relation, eliminating spatial dependency.This study presents experimental and numerical results for Wire and Arc Additive Manufacturing (WAAM) 316 L stainless specimens that deform from a standard initial cylindrical shape into well-defined ellipsoids upon impact as in the case of an anisotropic material. The measured thermal evolutions across the major and the minor axes of the ellipsoid are quite different, which might suggest that each direction possesses its own TQC when average plastic work is used. Numerical modeling allows for determining the local stress and strains on the el-lipsoid's surface. Using this data, our measurements show that the TQC is not affected by the orientation of the measurements. In other words, and in contrast to previous works, despite plastic anisotropy, the TQC remains isotropic.