Stabilization of retained austenite due to partial martensitic transformations

Journal Article · Thu Dec 01 04:00:00 EST 1994 · Acta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-7151(94)90189-9· OSTI ID:6767700

Xie, Z L; Liu, Y; Haenninen, H ^[1]

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1. Helsinki Univ. of Technology, Espoo (Finland). Lab. of Engineering Materials

The stabilization effect of retained austenite has been studied using Fe-Ni-C alloys with M[sub s] temperature below 0 C via a two-step cooling procedure, i.e. the samples were first cooled to a temperature (T[sub a]) below M[sub s] temperature and then heated to room temperature (RT), after being held at RT for a while, the samples were recooled to low temperatures (23 or 82 K) and then heated to RT. It was found that, during the second step of cooling, the martensitic transformation occurred at a temperature of M[prime][sub s] which was lower than T[sub a]. With increasing the amount of martensite formed during the first cooling, the difference in the martensitic transformation starting temperatures, [Delta]M[sub s] = M[sub s] [minus] M[prime][sub s], increased. The mechanism of the stabilization of retained austenite during the second step of cooling is proposed to be mainly due to the inhibition effect produced by the previously formed martensite. The aging processes, which retard the growth of the previously formed martensite plates and reduce the number of the available nucleation sites, are the necessary conditions for the above mechanism to operate. By simplifying the internal resisting stress acting on the retained austenite due to the existence of martensite phase as a hydrostatic compressive stress, which increases with increasing the amount of martensite, the change in [Delta]M[sub s] is discussed from a thermodynamic point of view.

• OSTI ID: 6767700
• Journal Information: Acta Metallurgica et Materialia; (United States), Journal Name: Acta Metallurgica et Materialia; (United States) Vol. 42:12; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
AUSTENITE
CARBON ADDITIONS
CRYSTAL-PHASE TRANSFORMATIONS
DATA
EXPERIMENTAL DATA
INFORMATION
IRON ALLOYS
IRON BASE ALLOYS
MAGNETIC PROPERTIES
MARTENSITE
MICROSTRUCTURE
NICKEL ALLOYS
NICKEL STEELS
NUMERICAL DATA
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
STABILIZATION
STEELS
TEMPERATURE DEPENDENCE