Some aspects of the behavior of metastable austenitic steels at high strain rates

Abstract

Metastable austenite containing steels, i.e., steels capable of undergoing solid-state phase transformation from austenite to α´-martensite during plastic deformation, offer a very good combination of ductility, strength, and above all, exceptional strain hardening capability. In effect, in suitable plastic deformation conditions the relatively soft austenitic phase can transform to the harder α´-martensite, which increases the strain hardening rate of the material through various mechanisms. This special feature gives these kinds of alloys several beneficial properties, such as resistance against flow instabilities and increased capability to absorb deformation energy. For this reason, metastable austenite containing alloys have been extensively studied in the past. However, several open questions still remain, especially in the field of high rate deformation. This can be related to the great number and complexity of the related microstructural phenomena and their combined effects on the material response. The open questions affect both the metallurgy of the material and the numerical modeling of material behavior. The current contribution addresses some of these questions and their possible solutions, as well as gives an outlook on the possible future development directions.