Crystallographic Analysis and Mechanism of Martensitic Transformation in Fe Alloys

A new version of the crystallographic theory of martensitic transformation has been developed, where instead of Bain deformation, the deformation of the lattice was performed by a shear along the twinning system of crystals and an additional change in dimensions in three mutually perpendicular directions. In the proposed variant, the angle of relaxation rotation of martensite crystal was about 1.8°; in the standard phenomenological theory, it was 10°. The new version made it possible to establish the mechanism of lattice deformation upon martensitic transformation, to determine the angle of relaxation rotation, and to carry out crystallographic analysis of martensitic transformation in various alloys. The formation of crystals (laths) of dislocation martensite in medium-carbon steel was found to occur with redistribution of carbon.