AN INTERNAL FRICTION PEAK DUE TO STRESS INDUCED α' MARTENSITE IN A SUS 304 STEEL

Abstract

An internal friction peak which is considered to be due to α' martensite phase in a cold worked 304L stainless steel has been found at 360K at the measurement frequency of about 500Hz by the present authors. This peak is different from the peaks which have been reported by Baraz et al. and Mezzetti et al. in cold worked 18-8 stainless steels. The present work has revealed that the 360K peak height increases with the concentration of solute carbon and nitrogen atoms. The β value, which is discussed in Nowick et al's papers is larger than 2.5 for the 360K peak. Accordingly, this peak is not a single relaxation peak such as a Snoek peak of solute carbon atom. The 360K peak is considered to be a cold work peak which is caused by the interaction between high density dislocations and solute carbon and nitrogen atoms in martensite phase.