Grain size dependence of intergranular lattice strain generated by plastic deformation in ferritic steel

友田 陽*; Li, H.*; 土田 紀之*; Gong, W.   ; Harjo, S.   ; 大村 孝仁*

Tomota, Yo*; Li, H.*; Tsuchida, Noriyuki*; Gong, W.; Harjo, S.; Omura, Takahito*

The uniaxial deformation behavior of low-carbon ferritic steels with grain sizes of 0.47 um and 1.5 um was studied using in situ neutron diffraction under tensile and compressive loading. The evolution of lattice strains was analyzed in terms of elastic anisotropy and grain-to-grain plastic incompatibility, which generates intergranular strains. Significant residual intergranular lattice strains were observed after both tensile and compressive plastic deformation. Transmission electron microscopy revealed grain-size-dependent dislocation structures, indicating increasingly constrained plastic relaxation near grain boundaries with grain refinement. Overall, the magnitude of residual intergranular lattice strains increases as grain size decreases to the submicrometer range.