Effect of ART-Annealing Conditions on Microstructural Regulation and Deformation Behavior of 0.17C-9Mn-3.5Al TRIP-Aided Steel

Abstract

The effects of annealing conditions on the microstructure and deformation mechanism of 0.17C-9Mn-3.5Al steel have been investigated. Through austenite reverted transformation (ART) annealing, a multiphase microstructure composed of d-ferrite, a-intercritical ferrite, g-austenite, and a'-martensite is obtained in as-forged specimens. For the specimen annealed at 750 8C for 60 min, a high volume fraction (42.19%) of retained austenite is attained, yielding a large total elongation (TE) of %38% and tensile strength (Rm) of %810 MPa and a two-stages work hardening behavior. The work hardening behavior analysis using the differential C-J model clarifies that the multistage can be mainly attributed to the discontinuous transformation induced plasticity (TRIP) effect, which is related to the volume fraction of retained austenite and its different stability levels as well as cooperative deformation of the multiphase microstructure. Thus, the active TRIP effect predominately affects the high strain stage, resulting in a higher work hardening ability and a increased plasticity.[ Ã ] X.

Effect of austenite stability on toughness, ductility, and work-hardening of medium-Mn steel

“…However, an obvious difference of 943 K sample was that the work-hardening curve dramatically fluctuated in stage 2. This phenomenon was mainly attributed to the discontinuous TRIP effect [16,17,42]. The discontinuous TRIP effect means that the TRIP effect occurred intermittently with increased true strain [16,43].…”

“…It was proposed by Cai et al [16] and Zhang et al [42] that the discontinuous TRIP effect primarily results from RA with different degree of stability. For cold rolled medium-Mn steels, the RA with different degree of stability was mainly because of uneven distribution of Mn [17].…”