Precipitation and Decomposition Behaviors of Reverted Austenite in 13Cr-4Ni Stainless Steel

Abstract

The study was made of the behavior of α′→γ reverse transformation and γ→α′ martensitic transformation as a function of prior microstructure in type SCS5 soft martensitic stainless cast steel by means of dilatometric measurements and metallographic observations. The initial retained austenite decreased with the increase of heating temperature beyond TAs because of unstabilization of austenite. In the heating range between TAs and TAf, dilatometric curves showed the noticeable shrinking for the specimens with the as-quenched and quenched & tempered structures, but the monotonous expanding for the specimens which was subjected to pre-treatment in the α+γ phase range. During cooling after the α′→γ reverse transformation, martensitic transformation occurred in which Ms increased with increasing total austenite content. The increase of the total austenite content resulted in unstabilizing itself, increasing the fresh martensite and consequently the hardness.