High elongation of medium-manganese steel containing 1.0 wt.% Al after a short intercritical annealing time

This paper presents research on the phase transformation, microstructure, and tensile properties of medium-manganese steel containing 1.0 wt.% Al (1.0Al) after a short intercritical annealing (IA) time at different IA temperatures using thermodynamic simulation, scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, and uniaxial tensile tests. The results show that the addition of 1.0A1 can expand the size of the IA temperature range from 208 to 272 degrees C and shifts the range to higher temperatures, and this increases the fractions of the retained austenite in the steel when the IA time is short. Most of the retained austenite transforms to alpha'-martensite during the tensile test. Part of the retained austenite transforms to alpha'-martensite in the early stage and contributes little plasticity. The other part of the retained austenite transforms in the middle or late tensile deformation stage and improves the mechanical properties. The mechanical properties of the steel are remarkable, with a tensile strength above 1000 MPa, elongation above 35%, and strength x ductility above 35,000 MPa% when the IA temperature is 700 degrees C and the IA time is 3 min. (C) 2020 The Author(s). Published by Elsevier B.V.