The Influence of Plastic Deformation on Lattice Defect Structure and Mechanical Properties of 316L Austenitic Stainless Steel

Abstract:

The effect of different plastic deformation methods on the phase composition, lattice defect structure and hardness in 316L stainless steel was studied. The initial coarse-grained γ-austenite was deformed by cold rolling (CR) or high-pressure torsion (HPT). It was found that the two methods yielded very different phase compositions and microstructures. Martensitic phase transformation was not observed during CR with a thickness reduction of 20%. In γ-austenite phase in addition to the high dislocation density (~10 × 10¹⁴ m^-2) a significant amount of twin-faults was detected due to the low stacking fault energy. On the other hand, γ-austenite was gradually transformed into ε and α’-martensites with transformation sequences γ→ε→α’ during HPT deformation. A large dislocation density (~133 × 10¹⁴ m^-2) was detected in the main phase (α’-martensite) at the periphery of the disk after 10 turns of HPT. The high defect density is accompanied by a very small grain size of ~45 nm in the HPT-processed sample, resulting in an very large hardness of 6130 MPa.

• Periodical: Materials Science Forum (Volume 885)
• Pages: 13-18
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.885.13
• Online since: February 2017
• Authors: Moustafa El-Tahawy, Jenő Gubicza, Yi Huang, Hye Lim Choi, Hee Man Choe, János L. Lábár, Terence G. Langdon
• Keywords: Defect Structure, Martensitic Transformation, Steel, α’-Martensite, γ-Austenite

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