Prediction of precipitation kinetics and strengthening in FeMnAlC lightweight steels

Abstract

Fe–Al–Mn–C steels have superior mechanical properties, such as high yield and tensile strengths and low density, which make them suitable for applications in the automotive and defense industries. In particular, the aging of these steels at certain temperatures and times results in the formation of nanoscale precipitates such as κ-carbide, which can significantly affect their mechanical properties. Therefore, the precise estimation of the size and amount of κ-carbide precipitates is necessary to predict and control the mechanical properties of lightweight steels. However, because κ-carbides precipitate rapidly, it is difficult to detect subtle changes early in the precipitation process. Furthermore, it is difficult to experimentally observe and quantify nanoscale precipitates. We conducted thermokinetic simulations of the aging of lightweight steel specimens to predict the phase fraction and size of the precipitated κ-carbides after various aging times and validated these results by comparison with experimental data. Next, we assessed models of precipitation strengthening based on different mechanisms. Additionally, the total yield strength was predicted by calculating the precipitation strengthening effect and estimating all the strengthening mechanisms affecting the yield strength, for example, grain boundary strengthening, solid solution strengthening, and dislocation strengthening.

Keywords

• Lightweight steel
• κ-carbide
• Precipitation
• Strengthening mechanism
• Thermokinetic simulation