Effect of metastable residual austenite on the mechanical properties of steels Kh12M

1. An increase in austenitizing temperature for steel Kh12M increases austenite stability in relation to martensitic transformation during cooling, but it confusingly affects its intensity during subsequent loading. Depending on its temperature, tempering may both stabilize and destabilize austenite. 2. The level of mechanical properties for steel Kh12M is governed not only by the original phase composition, but also the degree of γres → α-transformation development during mechanical testing. Achievement of 15–20% metastable residual austenite and its conversion into martensite makes it possible to provide the best combination of strength and ductility properties with static torsion tests. A predominatly austenitic structure with a certain degree of stability causes an increase in the level of ductility and impact resistance for steel Kh12M. 3. For specific loading conditions it is necessary to control the amount and degree of residual austenite stability, which provides achievement of the required mechanical and service properties.