Change in dislocation density via ausforming in Fe-5%Mn-C alloy with lath martensitic structure

Takanashi, Misa*; Hidaka, Ryota*; Okubo, Kota*; Masumura, Takuro*; Tsuchiyama, Toshihiro*; Morooka, Satoshi  ; Maeda, Takuya*; Nakamura, Shuichi*; Uemori, Ryuji*

This study investigates the strengthening mechanism of ausforming in martensitic steels, focusing on the role of dislocation inheritance from austenite. By analyzing Fe-5%Mn-C alloys, the researchers quantified dislocation densities before and after ausforming and examined how carbon content affects hardening. Results show that both hardness and dislocation density of ausformed martensite increase with greater deformation in austenite and higher carbon content. The findings support that ausforming strengthens martensite through dislocation accumulation, consistent with the Bailey-Hirsch relationship. neutron diffraction revealed that dislocation inheritance occurs only in steels with sufficient carbon, while additional dislocations are introduced during martensitic transformation.