High-Strength Precipitation-Hardening Austenitic Steels with Shape Memory Effect

Abstract

It has been shown that the conversion of austenitic manganese steels – via their purposeful alloying – into the class of precipitation-hardening materials (when aging leads to the formation of VC carbides) provides for high values (2.5-2.7 %) of the shape memory effect (SME) and considerable improvement in strength characteristics of the steels after aging and implementation of γ→ε→γ transformations. Strength characteristics and SME can be governed in wide limits by means of controlled changing of the amount, dispersity, and distribution of VC carbides during aging. The shape memory effect with a reversible deformation of 1.6—1.7% in the metastable steels such as 0.20C-20Mn-2Si-1V with an ε–martensite initial structure is obtained as a result of the retwinning of ε martensite during cold deformation and the subsequent ε→γ transformation during heating.