X-Ray diffraction study of the change in the structure of a VNS9-III TRIP sheet steel after static tension

The change in the phase composition of a cold-worked austenitic–martensitic VNS9-III TRIP steel after static tension at a strain rate of 0.1, 5, 7, and 10 mm/min is studied by X-ray diffraction. The steel in the initial state has the following three phases: fcc γ phase and two bcc phases (α 1 , α 2 ). A high degree of preferred (211) crystallite orientation is observed for the α 1 phase, and a preferred (100) orientation is observed for the α 2 phase. Deformation under static tension leads to a decrease in the content of austenite (γ phase) in the steel structure at the expense of formation of deformation martensite. The lower the strain rate, the lower the volume fraction of the γ-phase: it is 46% in the initial state, 36% at a tension rate of 10 mm/min, and 18% at a tension rate of 0.1 mm/min. The γ-phase content decreases mainly due to an increase in the α 1 phase content.