On the Mechanical Stability of Austenite Matrix After Martensite Formation in a Medium Mn Steel

The present work employs the nanoindentation technique to investigate the effect of prior martensite formation on the mechanical stability of a retained austenite matrix. It is found that the small austenite grains that were surrounded by martensite laths have higher mechanical stability than the la...

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Bibliographic Details
Published in:	Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2016-07, Vol.47 (7), p.3346-3353
Main Authors:	He, B. B., Huang, M. X.
Format:	Article
Language:	eng
Subjects:	Austenite Characterization and Evaluation of Materials Chemistry and Materials Science Defects Formations Grain size Grains Martensite Martensitic stainless steel Martensitic transformations Materials Science Mathematical analysis Mechanical properties Metallic Materials Metallurgy Microstructure Nanotechnology Stability Structural Materials Surfaces and Interfaces Thin Films
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Summary:	The present work employs the nanoindentation technique to investigate the effect of prior martensite formation on the mechanical stability of a retained austenite matrix. It is found that the small austenite grains that were surrounded by martensite laths have higher mechanical stability than the large austenite grains that were free of martensite laths. The higher mechanical stability of small austenite grains is due to its higher amount of defects resulting from the prior martensite formation. These defects act as barriers for the later martensite formation and therefore contribute to the higher mechanical stability of small austenite grains. As a result, the present work suggests that the formation of martensite tends to stabilize the surrounding austenite matrix. Therefore, it may explain the lower transformed amount of martensite after quenching as compared to the theoretical calculation using the Koistinen and Marburger (K–M) equation.
ISSN:	1073-5623 1543-1940