Deformation behavior in cold-rolled medium-manganese TRIP steel and effect of pre-strain on the Lüders bands

Abstract

Deformation behavior was studied in cold-rolled 0.2C-1.6Al-6.1Mn-Fe transformation-induced plasticity (TRIP) steel subjected to intercritical annealing. The steel intercritically hardened at 650℃ exhibited excellent mechanical properties, and the excellent ductility was primarily associated with the discontinuous TRIP effect. Moreover at 650℃, the formation of Lüders bands was associated with TRIP effect and cooperative dislocation glide. The length of Lüders strain was gradually reduced with increasing pre-strain, and was eventually eliminated when the pre-strain was increased to 10%. The increased average stability of retained austenite and increased dislocation density in ferrite induced by pre-strain was responsible for decrease and ultimate elimination of Lüders bands. While in steel intercritically annealed at 600℃, ferrite and austenite was predominantly deformed, which was responsible for poor work hardening rate and inferior tensile properties.

Influence of Intercritical Annealing Temperature on Microstructure and Mechanical Properties of a Cold-Rolled Medium-Mn Steel

“…At the same time, the intercritical annealing resulted in a softening of the material with improved ductility. In previous studies, it was pointed out the intercritical annealing temperature has a great effect on the fraction and stability of retained austenite [10,[48][49][50][51][52]. Consequently, the mechanical properties showed a strong dependence on intercritical annealing temperature ( Figure 10).…”

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

“…Second, the quenched samples were tempered at 200℃ for 20 min and air cooled to ambient temperature. Tempering effect has been previously studied by us [15]. Tempering was helpful in relieving the internal stresses, but more importantly it is expected to improve the stability of austenite through the diffusion of C from ferrite to austenite.…”

The critical factors governing mechanical properties in hot-rolled Fe-0.2C-11Mn-(0-6)Al TRIP steels and fracture behavior

“…In 6Al samples, the austenite fraction was similar ( Fig. 7), but the TE decreased with increase in quenching temperature, which was attributed to the decreasing austenite stability [21]. The reasons underlying the variation in TE with increase in Al-content can be further elucidated by studying their fracture surfaces and TEM micrographs of the fractured samples.…”