Difference in transformation behavior between ferrite and austenite formations in medium manganese steel

Strong and ductile medium Mn steel without transformation-induced plasticity effect

“…The lamella structure contains dual-phase microstructure of ferrite and austenite grains (Figure 1(c)). Some lamella austenite grains are fully surrounded by lamella ferrite grains (arrows in Figure 1(c,d)), suggesting that some austenite grains are nucleated at the prior martensite lath boundaries [16]. The orientation relationship between lamella austenite grains and adjacent lamella ferrite grains is close to Kurdjumov-Sachs (K-S) relation (42.85°/ < 114 > ) according to the angle-axis values [17].…”

“…The austenite reverse transformation takes place during annealing at 700°C as confirmed from the contraction of dilatometry sample (Figure 4(d)). The fast austenite reverse transformation kinetics (Figure 4(d)) could be due to intensive lath boundaries and high dislocation density in lath martensite [16]. The austenite grains tend to nucleate at and grow along the martensite lath boundaries [16], leading to the formation of lamella austenite grains (Figure 1(c)).…”

“…The fast austenite reverse transformation kinetics (Figure 4(d)) could be due to intensive lath boundaries and high dislocation density in lath martensite [16]. The austenite grains tend to nucleate at and grow along the martensite lath boundaries [16], leading to the formation of lamella austenite grains (Figure 1(c)). The residual lath martensite remains in a lamella morphology with a high dislocation density (Figure 3(b)).…”

Microstructure and Tensile-Shear Properties of Resistance Spot-Welded Medium Mn Steel

“…Studies relevant to medium Mn steel are mainly focused on (0.1-0.2)C(3-10)Mn (wt %) steels with a certain amount of austenite [6][7][8]. The final microstructure is usually controlled to be ferrite + austenite dual phases by inter-critical annealing between the start (A s ) and finish (A f ) temperatures of the reverse transformation after hot-rolling or cold-rolling, during which the ferrite or martensite transforms into austenite [2,9]. It should be noted that the retained austenite in medium Mn steel is essential to obtain high strength with high ductility, which derives from the deformation-induced transformation of retained austenite to hard martensite.…”

Effects of impact energy on the wear resistance and work hardening mechanism of medium manganese austenitic steel

“…Jing and Jiang [8] discovered that the high-rate work hardening of medium manganese steel under impact abrasion wear is due to the transformation of strain-induced martensite, but they did not research the effect of different impact energies on the work hardening mechanism and degree. Another work by Nakada et al [9] investigated the differences between ferrite and austenite formations of medium manganese steel in transformation behaviors, which revealed the transformation behavior between γ to α and α to γ at the transition temperature, but did not reveal any work hardening mechanism apart from martensite transformation. To increase the surface hardness of medium manganese austenitic steel (MMAS), Xu [10] investigated the process of eutectic growth in as-cast medium manganese steel and explained the mechanism of modularization of the eutectic.…”