On the Grain Growth Kinetics of a Low Density Steel

The grain growth kinetics of an age-hardenable Fe-Mn-Al-C steel were investigated. Kinetics of grain growth were determined between 1173 and 1348 K (900–1075 °C) to obtain a range of grain sizes from 30 to 475 μm. It was found that grain growth was negligible at 1173 K (900 °C) for times up to 15 h. The activation energy for grain growth was found to be 467 kJ/mol. The hardness and mean linear intercept (L3) were correlated to follow a traditional Hall-Petch relationship. Tensile properties of the alloy were determined after various solution treatments performed for 2 h followed by water quenching. Tensile strength increased from 810 to 960 MPa and ductility was reduced from 80 to 60% as the grain size decreased from 200 μm to 30 μm as grain coarsening was mitigated by lowering the solution treatment temperature.