Internal friction on AISI 304 stainless steels with low tensile deformations at temperatures between - 50 and 20 °c

Abstract

Austenitic stainless steels specimens were deformed by tension in temperatures in the range of - 50 °C to 20 °C and 0.03 to 0.12 true strain, in order to obtain different volumetric fractions of ε (hexagonal close packed) and α′ (body centered cubic) strain induced martensites. The morphology, distribution and volumetric fractions of the martensites were characterized by metallography and dilatometry analysis and quantified by ferrite detector measurements. The damping behavior of specimens with different volumetric fractions of martensites was studied in an inverted torsion pendulum in the 40 °C to 400 °C range. The ε- and α′-martensites reversion was observed in the temperature range of 50 °C 200 °C and 500 °C 800 °C, respectively, by dilatometry. Internal friction curves in function of temperature of the deformed samples presented internal friction peaks. The first internal friction peak is related to sum of the amount of ε- and α′-martensites. For low deformations it aligns around 130 °C and it is related only to the ε → γ reverse transformation. The peak situated around 350 °C increases with the specimen degree of deformation and is, probably, related to the presence of α′/γ interfaces, and deformed austenite. Copyright © 2010 T. F. A. Santos and M. S. Andrade.