Memory effects of transformation textures in steel and its prediction by the double Kurdjumov-Sachs relation

The phenomenon that the transformation texture near the initial texture reproduces after the phase transformation cycle such as ferrite (α, body-centered cubic) → austenite (γ, face-centered cubic) → α is called a texture memory. In this study, the texture change in a 0.1% C-1% Mn hot-rolled steel sheet during the α → γ → α transformation cycle was studied via neutron diffraction and the transformation texture prediction based on a variant selection rule that we call the double Kurdjumov-Sachs (K-S) relation. The texture change observed by neutron diffraction, which clearly showed the texture memory, could be quantitatively reproduced by the proposed variant selection rule adopted into the calculation method based on the spherical harmonics expansion of orientation distribution functions. Therefore, it is most likely that the texture memory in steel is caused by the preferential selection of those K-S variants that reduce the interfacial energy between a precipitate and two adjoining parent phase grains at the same time, which we call the double K-S relation.