Microstructural evolution and deformation behavior in the Fe-(6, 8.5)Mn-3Al-0.2C TRIP steels

Abstract

We have studied here the microstructural evolution and deformation behavior in two hot-rolled Fe-6Mn-3Al-0.2C (6Mn steel) and Fe-8.5Mn-3Al-0.2C (8.5Mn steel) transformation induced plasticity (TRIP) steels. Excellent combination of mechanical properties including total elongation (TEL) of 39.3%, ultimate tensile strength (UTS) of 1112 MPa and UTS×TEL of 43.7 GPa% were obtained in 8.5Mn steel subjected to intercritical hardening at 750℃ and tempering at 200℃. The increase in the Mn-content in the experimental steel led to increase in the volume fraction of austenite and change in austenite morphology. Non-uniform Mn distribution in austenite with varied morphology resulted in different degree of austenite stability and led to discontinuous TRIP effect, contributing to the best combination of mechanical properties in 8.5Mn-750 steel.

The Novel Combination of Strength and Ductility in 0.4C‐7Mn‐3.2Al Medium Manganese Steel by Intercritical Annealing

“…The relationship between the UTS and TE can be expressed by the so‐called banana curves for various AHSS grades. Figure summarizes the UTS and TE data of medium Mn steels in this study and in available literatures with similar Mn content levels . As shown, significantly superior tensile properties could be obtained in this study.…”

“…Li et al suppose that martensite transformation is the main reason for quick increase and abrupt drop in the d σ /d ε curve. Li et al proposed that excellent strength and plasticity in medium Mn steel might be attributed to the discontinuous TRIP effect involving stress relaxation and transfer during deformation. As indicated in the enlarged zone of the d σ /d ε curve, when some RA grains start to transform as fresh martensite intensively, d σ /d ε increases quickly from P 1 (1496 MPa) to the larger value (P 2 , 3462 MPa), then abruptly drops to P 3 (1302 MPa).…”

Microstructure-mechanical property relationship and austenite stability in medium-Mn TRIP steels: The effect of austenite-reverted transformation and quenching-tempering treatments

“…The aforementioned results suggest that in the case of ART process, the ultimate tensile strength (UTS) and total elongation (TEL) decreased continuously with increase in austenitization temperature. Based on our earlier studies [23,24], the ultimate tensile strength is determined by austenite fraction and TRIP effect. It is clear that the volume fraction of retained austenite (measured by XRD) in steels subjected to ART process decreased with increase in austenitization temperature (Fig.…”

A Novel Cyclic-Quenching-ART for Stabilizing Austenite in Nb–Mo Micro-Alloyed Medium-Mn Steel

“…S2, which exhibited a small negative slope value, is determined by the coordinated deformation of ferrite-dominated and partially relatively low-stability austenite [28,29], because there is a reduction by~29-34% in the amount of austenite at this stage (Figure 4a). S3 is characterized by strong WHR due to the coordinated deformation of austenite-dominated, ferrite and the martensite produced by the TRIP effect [30][31][32], because there is a reduction by~34-100% in the austenite content at this stage (see Figures 3d and 4a). Estimating the tensile flow stress of experimental steels using Equation (7) [33]:…”