Warm Forming of FCC Poly Crystals: The Effect of Grain Size under Different Forming Conditions on the Softening Behavior

Abstract

Ingot breakdown is the most significant process for achieving high-quality billets in the cogging process. Especially microstructure evolution and grain refinement during the plastic deformation are of technical interest for the metal forming industry. To obtain refined and uniform microstructures after processing, it is necessary to understand deformation mechanisms as well as recovery-and recrystallization phenomena. Polycrystalline pure nickel and cast structured austenitic stainless steels were deformed by a compression test at different warm forming temperatures (800-1200°C) to investigate the influence of initial grain size, strain and strain rate on the structural refinement process. To get rid off static-and postdynamic softening processes the samples were immediately water quenched after deformation. By using the electron back scatter diffraction technique, the microstructural evolution and the crystallographic orientations were captured after deformation.