Ultrahigh Strength-High Ductility Combination Low Density Austenitic Steel: Effect of Aging Temperature and Strain Rate
The objective of the study was to optimize the post-thermal treatment of hot rolled Fe-0.92C-26.3Mn-8.79Al-0.05Nb steel. In this regard, the hardness of the experimental steel was studied as a function of aging time and/or strain rate. The study provided an understanding of aging heat treatment for the experimental steel, which was processed by vacuum induction melting, followed by thermo-mechanical rolling involving multiple passes. The rolled steel was subsequently annealed at 900 °C for 4 h followed by water quenching. X-ray diffraction in scanning mode of 2θ=20-100o indicated the presence of austenite structure. In order to study the influence of aging at 550 °C for 20 h, mechanical properties (yield strength, ultimate tensile strength, and elongation) were determined via tensile tests and compared with as-rolled and solution treated at 950 °C for 1, followed by quenching. Additionally, to study the effect of aging for different times (1, 10, 25, 50, 75 h) at 500 °C, Vickers hardness measurements indicated increase of hardness with aging time, and there was a different of ~138 HV1 between 1 h and 75 h aged samples. Scanning electron microscopy was used to study microstructural variation on 1 h and 75 h aged samples. The size of annealing twins for each aging time was measured using Image J software. Lastly, the effect of strain rate on hardness values was studied. The study enabled the optimization of post-thermal treatment on Fe-Mn-Al-C-Nb low-density steel.
Kim, Jaehyun, "Ultrahigh Strength-High Ductility Combination Low Density Austenitic Steel: Effect of Aging Temperature and Strain Rate" (2022). ETD Collection for University of Texas, El Paso. AAI29210087.