2019 年 60 巻 703 号 p. 215-220
A new physical simulation method for evaluating the effect of shear deformation on the evolution of a microstructure is proposed using niobium-bearing steel. The effects of the processing conditions, such as pre-heat treatment, strain rate, and cooling rate, on the formation of ultrafine grains were experimentally examined by the shearing method named the “interrupt shearing test”. This method utilizes a high-speed compression testing machine and is capable of simulating the formation of fine grained steel in the phase transformation procedure. Large shear deformation has been reproduced by the proposed method, and a grain size of approximately 1μm has been obtained by controlled mist cooling.