Texture Evolution in Low Carbon Steel Fabricated by Multi-directional Forging of the Martensite Starting Structuree

It has been clarified that deformation and annealing of martensite starting structure can produce ultrafine-grained structure in low carbon steel.  This study aims to investigate the texture evolution and mechanical properties of samples with martensite structure deformed by two different forging processes. The martensitic steel samples were forged by plane strain compression and multi-directional forging up to the same true strain of 2.  All samples were then annealed at 450 and 550°C for 30 min.  It was found that the active slip systems in the BCT crystalline structure of martensite acted like ferrite steel. After the multi-directional forging of martensitic steel, the yield and ultimate strength greatly increased to 1278 and 1658 MPa, respectively. During annealing, in the plane strain compressed sample, the "oriented nucleation" and in the multi-directional forged specimen, the "selective growth" theory was dominant.