Papers by Keyword: Heavy Deformation

Abstract: The silicon steel was rolled to 95% reduction at 20°C, 400°C and 600°C, and subsequently annealed at different temperatures to obtain complete recrystallization microstructure without appreciable grain growth. The effects of rolling temperature on through-thickness deformation and recrystallization textures were investigated by ODF analysis. The deformation textures are all composed of α- and γ-fiber, whereas α-fiber and {111}﹤110﹥ decrease and {111}﹤112﹥ increases with the increasing rolling temperature. Through-thickness recrystallization texture varied significantly, a strong partial γ-fiber spreading from {111}﹤112﹥ or {554}﹤225﹥ to {111}﹤134﹥ and {114}﹤481﹥ are developed in steel sheet rolled at 20°C and 400°C, while a dominated η-fiber peaked at {310}﹤001﹥ is formed between surface and quarter thickness in steel sheet rolled at 600°C. The different recrystallization textures can be ascribed to the profuse shear band at 600°C compared with the microstructures at 20°C and 400°C.

Abstract: The formation of ultrafine-grained structure in steels by various thermomechanical processings is reviewed from a metallurgical point of view. In the recent new type TMCP, ultrafine ferrite grains with a grain size of about 1μm are obtained when the austenite is heavily deformed at lower temperatures. In this case, dynamic phenomena such as dynamic recrystallization become prominent in the process. In the aging after heavy cold rolling of supersaturated matrix phase in two-phase alloys, the competition between the recovery or recrystallization of matrix phase and the precipitation of second phase occurs, resulting in various types of two-phase structures including microduplex structure. Microduplex structure is also obtained by annealing after heavy cold rolling of coarse two-phase structure in duplex stainless steel and high carbon steel. Recently, various severe plastic deformation processings, in which very large plastic strain over 4 is applied to the materials, have been developed to produce ultrafine grained materials with nanocrystalline and/or submicrocrystalline structures.