Compression Deformation Behavior of a Fe–26Mn–7Al–1.3C Austenitic Steel after Precipitation‐Hardened Treatment

Abstract

Room temperature compression deformation behavior of a Fe–26Mn–7Al–1.3C austenitic steel in association with deformation microstructures is investigated in the article. After isothermal annealing at 550 °C for 2 h, a substantial nano‐sized κ‐carbides are precipitated within the austenite matrix. The precipitation‐hardened steel obtains an excellent combination of yield strength and toughness (product over 97 000 MPa J cm−2) associated with multiple‐stage strain hardening. In order to clarify the chief deformation mechanism, deformation microstructures are analyzed at different strain levels by means of transmission electron microscopy (TEM). TEM results show that the deformation microstructures exhibit the typical planar glide characteristics due to “glide plane softening” effect in spite of the high SFE (≈72 mJ m−2) for current steel. Some specific planar dislocation configurations including Taylor lattices and micro‐bands are contributed to high constant strain hardening rate. However, at high strain, intersections of highly localized nature micro‐bands decrease the formation activity of slip bands, meanwhile, the interaction between κ‐carbides and dislocation cross‐slip becomes more intensive, which results in a decrease in the growth rate of dislocations due to the frequency of dislocation annihilation.