A special intermediat temperature phase transformation phenomena in the high nitrogen (approximately 2 8%wt N) austernite was discussed in this paper. Many fine nuclei sprouted out in crystal boundary and intercrystalline of the austernite,more fine precipitates can be observed in these nuclei.The growth speed of the nuclei were very slow and the number of the decomposed nuclei increase constantly.Finally the nuclei joint together and a highly disperse
products with many fine precipitates in them formed in the entire area.It is obviously different from the tempered
martensite and normal needle or plate
structure of bainite products.The hardness of the products is higher than that of the tempered martensite and can up to 900HV.The dynamics characteristics of phase transformation are a long incubation time and a complete decomposition of austenite.The
initial observation shows that the structure pattern and the dynamics characteristics of phase transformation are quite different from the bainite and martensite transformation.