Low-temperature properties of strain-hardened austenitic stainless steels containing nitrogen

Abstract

1. Low-carbon austenitic steels containing nitrogen are strengthened considerably by deformation at normal and low temperatures. The yield strength of stable austenitic steel 03Kh20N16AG6 at 77°K depends only on the preliminary deformation and is prctically independent of the temperature. 2. To ensure high strength of stable austenitic steels containing nitrogen the deformation can be conducted at room temperature. The absolute values of the strength characteristics of stable austenitic steel 03Kh20N16AG6 deformed 30% at room temperature and metastable steels 03Kh18N11 and 03Kh19AN12 deformed at low temperature are almost identical. 3. The ductility of stable austenitic steel 03Kh20N16AG6 strengthened by deformation at room temperature is quite adequate and the steel can be used for cryogenic equipment. Its yeild strength increases to 190 kgf/mm2 at 77°K and to 110 kgf/mm2 at room temperature. 4. The change in the fracture toughness of steel 03Kh19AN12 at 77°K after small preliminary deformations (up to 5%) depends mainly on the reduction of the work of crack initiation. The reduction of the work of crack propagation with increasing preliminary deformation is due mainly to inhibition of the formation of strain martensite. With over 30% martensite the initiation of fracture is facilitated.