Effect of strain rate on the strain-induced γ, → α′-martensite transformation and mechanical properties of austenitic stainless steels

Juho Talonen*, Pertti Nenonen, Gersom Pape, Hannu Hänninen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

312 Citations (Scopus)

Abstract

The effect of strain rate on strain-induced γ → α′-martensite transformation and mechanical behavior of austenitic stainless steel grades EN 1.4318 (AISI 301LN) and EN 1.4301 (AISI 304) was studied at strain rates ranging between 3 × 10-4 and 200 s-1. The most important effect of the strain rate was found to be the adiabatic heating that suppresses the strain-induced γ → α′ transformation. A correlation between the work-hardening rate and the rate of γ → α′ transformation was found. Therefore, the changes in the extent of the α′-martensite formation strongly affected the work-hardening rate and the ultimate tensile strength of the materials. Changes in the martensite formation and work-hardening rate affected also the ductility of the studied steels. Furthermore, it was shown that the square root of the α′-martensite fraction is a linear function of flow stress. This indicates that the formation of α′-martensite affects the stress by influencing the dislocation density of the austenite phase. Olson-Cohen analysis of the martensite measurement results did not indicate any effect of strain rate on shear band formation, which was contrary to the transmission electron microscopy (TEM) examinations. The β parameter decreased with increasing strain rate, which indicates a decrease in the chemical driving force of the γ → α′ transformation.

Original languageEnglish
Pages (from-to)421-432
Number of pages12
JournalMETALLURGICAL AND MATERIALS TRANSACTIONS A: PHYSICAL METALLURGY AND MATERIALS SCIENCE
Volume36 A
Issue number2
DOIs
Publication statusPublished - Feb 2005
MoE publication typeA1 Journal article-refereed

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