Microstructural manifestation of dynamic strain aging in AISI 316 stainless steel

• Published in: Journal of nuclear materials Vol. 395; no. 1; pp. 156 - 161
• Main Authors: Karlsen, Wade, Ivanchenko, Mykola, Ehrnstén, Ulla, Yagodzinskyy, Yuriy, Hänninen, Hannu
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-12-2009; Elsevier
• Subjects: Applied sciences; Controled nuclear fusion plants; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Fuels; Installations for energy generation and conversion: thermal and electrical energy; Nuclear fuels; Stainless steel; Ageing; Nitrogen; Diffusion; Microstructure; Tension test; Nuclear reactor
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2009.10.047

Dynamic strain aging (DSA) affects a material’s mechanical behaviour. In the current study, the deformation microstructures of AISI 316 stainless steel specimens were examined after tensile testing at several temperatures both in and out of the DSA-regime (200, 288 and 400
°C), and the effect of straining on free nitrogen evolution at those temperatures was studied by Anelastic Mechanical Loss Spectrometry (Internal Friction). Analysis of the nitrogen-induced Snoek-like peak after straining indicated that DSA behaviour is associated with the formation of sub-micron scale, nitrogen-enriched zones in the austenitic matrix. Long-range planarity was observed in the dislocation structures at 400
°C and short-range planarity at 288
°C, but at 200
°C the microstructure exhibited cellular dislocation structure. Diffusion re-distribution of nitrogen in the DSA-regime affected the deformation behaviour of the material by restricting cross-slip, which in turn promotes strain localization, degrading the mechanical performance of the material.