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Deformation Induced Martensite Formation and its Effect on Transformation Induced Plasticity (TRIP)
Author(s) -
Weiß Andreas,
Gutte Heiner,
Scheller Piotr R.
Publication year - 2006
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.200606454
Subject(s) - martensite , materials science , plasticity , austenite , elongation , deformation (meteorology) , metastability , atmospheric temperature range , stress (linguistics) , metallurgy , diffusionless transformation , composite material , thermodynamics , ultimate tensile strength , microstructure , chemistry , physics , linguistics , philosophy , organic chemistry
The knowledge of the stress‐ and deformation‐induced martensite formation in metastable austenitic steels including the formation temperatures and amounts formed is of considerable importance for the understanding of the transformation induced plasticity. For this purpose a stress‐temperature‐transformation (STT) and a deformation‐temperature‐transformation (DTT) diagram have been developed for the steel X5CrNi 18 10 (1.4301, AISI 304). It is shown that the M d ‐temperature for γ→∊, ∊→α', γ→∊→α’ and γ→α’ martensite formation is defined by two stress‐temperature curves which show a different temperature dependence. They specify the beginning and the end of the deformation‐induced martensite formation in the range of uniform elongation. The intersection point defines the corresponding M d ‐temperature. The stress difference which results from the stresses for the end and the beginning of the martensite formation shows positive values below the M d ‐temperature. It defines the amount of martensite being formed. When the M d γ→∊ temperature is reached and the formation of the first deformation‐induced amount of ∊‐martensite appears, an anomalous temperature dependence of the maximum uniform elongation starts. The highest values of the maximum uniform elongation are registered for the tested steel in the immediate vicinity of the M d γ→α' or the M d γ→∊→α' temperature ‐ similar as in other metastable austenitic CrNi steels. At this temperature the highest amount of deformation‐induced ∊‐phase exists. The transformation plasticity in the test steel is considerably caused by the deformation‐induced ∊ and α’ martensite formation. Using the new evaluation method, the increase of plasticity ΔA (TRIP‐effect) and strength ΔR can be quantified.