An aspect of the nucleation of burst martensite

Abstract

In steels where the martensite transformation occurs in a well-behaved and progressive manner, it has been experimentally established that the number of pre-existing nuclei that develop into new plates of martensite (per unit volume of austenite) on undercooling below the martensite transformation temperature,M _s, is directly related to the corresponding increase in transformation driving force. Such a relationship cannot, however, be studied in steels which transform by a “burst” mechanism, since the role of the initial distribution of nuclei is swamped by the creation of numerous new (autocatalytic) nuclei. In the present work, an experiment designed to overcome this difficulty by suppressing the growth of autocatalytically generated nuclei is conducted, thus enabling the verification of the above relationship for a classic Fe-Ni-C burst-transformation alloy.