Effect of molybdenum, aluminium and boron on the phase transformation in 4 wt.–% manganese steels
Alexander Gramlich, C. van der Linde, Marc Ackermann, Wolfgang Bleck
Abstract
The transformation behavior of medium manganese steels after forging has been characterized using dilatometry in order to investigate the influence of the alloying elements. The alloys contain 4 wt.–% manganese, 0.5 wt.–% silicon, 0.035 wt.–% niobium and varying amounts of carbon (0.15–0.19 wt.–%), aluminum (0.025–0.5 wt.–%), molybdenum (0.02–0.2 wt.–%), titanium (0–0.02 wt.–%), and boron (0–0.06 wt.–%). The continuous cooling transformation (CCT) diagrams and a multiple linear regression (MLR) formula for calculating the martensite start (Ms) temperature is presented. The results are critically compared to a variety of formulae available in the literature. It is demonstrated within this study that molybdenum increases the Ms-temperature, silicon has no mandatory influence on the Ms-temperature and boron not only decreases the Ms-temperature but also increases the critical cooling rate. The new formula enables the precise setting of annealing parameters.