Effect of Cold Rolling on the Phase Composition, Texture, and Residual Stresses in Steels with 15.9 and 17.7% Mn

Abstract—X-ray diffraction analysis is used to investigate the phase composition, texture, and residual macrostresses in Fe–15.9Mn–0.007C and Fe–17.7Mn–0.03C steels in their initial quenched (at 1100°C) state and after subsequent cold rolling to 20–80% reductions. The quenched state of both steels shows the presence of three phases: α', γ, and ε. The ε-phase content decreases from initial values of 65 and 85% to 10–15 and 25–40%, respectively, for Fe–15.9Mn–0.007C and Fe–17.7Mn–0.03C steels after a reduction of 40–60%. The α'-phase content increases to 85–90 and 60–75%, respectively. Lattice strain calculations during the ε → α' and α' → ε phase transformations show preferential transformations during rolling. The texture evolution of the ε phase indicates that the Fe–15.9Mn–0.007C steel undergoes both the ε → α' transformation, causing volume expansion and compressive stresses, and the α' → ε transformation, resulting in volume contraction and tensile stresses. This explains the low level of residual stress in this steel, which varies from –100 to +100 MPa. In contrast, the Fe–17.7Mn–0.03C steel undergoes only the ε → α' transformation during cold rolling at all reductions, generating compressive stresses of 200–400 MPa due to volume expansion.