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Austenite reversion in 18 Ni Co‐free maraging steel
Author(s) -
Sinha P. P.,
Sivakumar D.,
Babu N. S.,
Tharian K. T.,
Natarajan A.
Publication year - 1995
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199501160
Subject(s) - maraging steel , austenite , martensite , materials science , metallurgy , reversion , transmission electron microscopy , diffusionless transformation , dissolution , microstructure , chemistry , biochemistry , gene , phenotype , nanotechnology
The mechanism of austenite reversion in 18 Ni Co‐free maraging steel (250 grade) has been established by conducting extensive X‐ray diffraction (XRD) and transmission electron microscopy (TEM) under differently aged conditions. It has been proposed that contrary to the precipitate dissolution mechanism suggested for the initiation of austenite reversion in 18Ni‐8Co‐5Mo type maraging steels, the initiation of transformation of martensite to austenite in this type of maraging steel is due to the diffusion of Ni from matrix to the dislocations and other defect structures on prolonged/high temperature ageing. This results in local enrichment of Ni which lowers both A S and M S temperatures of the region. Lowering of these transformation temperatures is responsible for the early reversion of martensite to Ni‐enriched stable austenite which, on subsequent cooling to room temperature, does not transform back to martensite.