Reverse martensitic transformation and resulting microstructure in a cold rolled metastable austenitic stainless steel

• The reverse martensitic transformation in cold-rolled metastable austenitic stainless steel has been investigated via heat treatments performed for various temperatures and times. The microstructural evolution was evaluated by differential scanning calorimetry, X-ray diffraction and microscopy. Upon heat treatment, both diffusionless and diffusion-controlled mechanisms determine the final microstructure. The diffusion reversion from α′-martensite to austenite was found to be activated at about 450°C and the shear reversion is activated at higher temperatures with Af′ ∼600°C. The resulting microstructure for isothermal heat treatment at 650°C was austenitic, which inherits the α′-martensite lath morphology and is highly faulted. For isothermal heat treatments at temperatures above 700°C the faulted austenite was able to recrystallize and new austenite grains with a low defect density were formed. In addition, carbo-nitride precipitation was observed for samples heat treated at these temperatures, which leads to an increasing Ms-temperature and new α′-martensite formation upon cooling.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Annan materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Other Materials Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Metallurgi och metalliska material (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Metallurgy and Metallic Materials (hsv//eng)

Keyword

Metastable austenitic stainless steel

Reverse martensitic phase transformation

Heat treatment

Microstructure

Engineering Materials

Materialteknik

Publication and Content Type

ref (subject category)

art (subject category)