Maraging-300: a structural and hyperfine study of steel aging

In this study, plates of solubilized Maraging-300 steel were aged at 480 °C, 580 °C, and 650 °C for 3 h and 6 h and then characterized by X-ray diffraction and 57Fe Mossbauer spectroscopy. The results show that solubilized steel is effectively martensitic, with a crystallographic distortion from the cubic symmetry usually attributed to the martensite. The aging treatments induce an atomic rearrangement in the martensite phase, involving a change in the local composition and lattice parameters, and the reversion of austenite in amounts that vary with the time and the temperature of the heat treatment. The tetragonal distortion from cubic symmetry presented by the martensite in the solution-annealed steel persists after aging. No intermetallic compounds were identified in any of the aged samples. The lattice parameters of the martensite and austenite phases, as well as their hyperfine parameters, were obtained at all aging conditions. The phase transformations found for Maraging-300 steel are compared with those for Maraging-350 and -400 steels aged in similar conditions.