Grain refinement and strengthening of austenitic stainless steels during large strain cold rolling

ABSTRACT

The microstructure/texture evolution and strengthening of 316 L-type and 304 L-type austenitic stainless steels during cold rolling were studied. The cold rolling was accompanied by the deformation twinning and micro-shear banding followed by the strain-induced martensitic transformation, leading to nanocrystalline microstructures consisting of flattened austenite and martensite grains. The fraction of ultrafine grains can be expressed by a modified Johnson-Mehl-Avrami-Kolmogorov equation, while inverse exponential function holds as a first approximation between the mean grain size (austenite or martensite) and the total strain. The deformation austenite was characterised by the texture components of Brass, {011}<211>, Goss, {011}<100>, and S, {123}<634>, whereas the deformation martensite exhibited a strong {223}<110> texture component along with remarkable γ-fibre, <111>∥ND, with a maximum at {111}<211>. The grain refinement during cold rolling led to substantial strengthening, which could be expressed by a summation of the austenite and martensite strengthening contributions.

KEYWORDS:

• Austenitic stainless steel
• deformation twinning
• shear bands
• strain-induced martensite
• ultrafine grains
• texture
• strength

Acknowledgments

The authors are grateful to the personnel of the Joint Research Centre, Belgorod State University, for their assistance with instrumental analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Andrey Belyakov http://orcid.org/0000-0001-9003-9416