Austenite reversion and nano-precipitation during a compact two-step heat treatment of medium-Mn steel containing Cu and Ni

Yield Strength Enhancement Without Ductility Loss Through Controlling the Intercritical Annealing Time in Medium‐Mn Steels

“…More details on the detailed analysis of tip IA-2 and IAT-2 are presented earlier in ref. [26]. As illustrated in Figure 5, the clustering behavior of Cu, Ni in addition to Al, and Mn appearing in the T-500, IAT-1, and IAT-2 reflects the common tendency of the coprecipitation of the CRP alongside Mn-enriched NiAl or NiAl.…”

“…In the previously published work of this study, [24][25][26] the processing route and heat treatment parameters in a two-step IAT were designed and optimized to obtain the best ductility. To study the effect of IA time on the microstructure, nanoprecipitates, and mechanical properties, two categories including four processing variants were designed.…”

“…Nonetheless, exceeding the optimal amount of Ni þ Al þ Mn þ Cu at% content, led to the loss of not only ductility but also YS [6] and hardness. [8] In our previous research work, [24][25][26] a two-steps process of intercritical annealing (IA) for 2 min followed by a 3 h tempering step was developed. The processing route and heat treatment parameters with respect to the annealing time and tempering temperature were optimized to achieve an MMnS alloy that contains CRP and Ni(Al/Mn) precipitates with better mechanical properties, namely, ductility.…”

“…With this two-fold strategy, a higher yield strength without loss of ductility should be achieved via a two-steps "intercritical annealing and tempering (IAT) process". [24][25][26] In this work, the precipitation formation is evaluated by investigating three processing variants consisting of only IA, only tempering (T-500), and IAT. Moreover, the IA time in the two-step process (IAT) is shortened and its effects on the precipitates number density, austenite fraction, and stability and consequently the mechanical properties, especially the ductility and yield strength, are evaluated using tensile tests and microstructure investigations using multiscale analyzing techniques including electron backscattering diffraction (EBSD), synchrotron (SYXRD), and atom probe tomography (APT).…”

Microstructure Evolution of Medium-Manganese Al-Alloyed Steel Manufactured by Double-Step Intercritical Annealing: Effects of Heating and Cooling Rates

“…Medium manganese steels containing 3-12 wt% of Mn are potential candidates suited for automotive applications, where the high strength together with good ductility are needed. Medium-Mn steels offer the product of tensile strength and total elongation at a level of 30-50 GPa% [1][2][3]. The beneficial mechanical properties exhibited by medium-Mn steels are attributed to the presence of metastable retained austenite (RA), which transforms into martensite upon deformation leading to transformation induced plasticity (TRIP) effect.…”