Martensite in interstitial-free steel obtained by ultra-high pressure

An interstitial-free steel was austenitized and cooled in a high-pressure high-temperature apparatus. Despite its inherently negligible hardenability, an interstitial-free steel with a full martensitic structure could be obtained even without quenching. Under atmospheric pressure, the microstructure after austenitization and cooling at an even faster rate consisted of massive ferrite. The thermodynamic stabilization of austenite by high pressure (on the gigapascal scale) led to great retardation of ferrite transformation and resulted in a rare microstructure of martensite in interstitial-free steel.