Critical role of ?-carbides in the multi-stage work hardening process of a lightweight austenitic steel

The multi-stage work hardening process of an Fe-Mn-Al-C lightweight austenitic steel has been experimentally examined, focusing on the critical role of kappa-carbides. The inhibition of kappa-carbides to the motion of dislocations at the initial elasto-plastic transition stage contributes to a high yield strength. The "slip plane softening" effect caused by the shearing of kappa-carbide particles by moving dislocations is mainly responsible for the formation of planar-slip dislocation substructure, leading to the occurrence of working hardening rate recovery stage and a plateau stage. The high sustained work hardening ability, resulting from the kappa-carbide induced planar-slip characteristics, increases the flow stress to reach the critical stress for nucleating deformation twins, which plays a positive role in the work hardening behavior at the last deformation stage.