THE EFFECT OF COOLING MEDIUM ON THE （的冷却介质的影响）.pdf

Journal of Materials Science and Engineering with Advanced Technology Volume 2, Number 2, 2010, Pages 165-175 THE EFFECT OF COOLING MEDIUM ON THE AUSTENITE-FERRITE EQUILIBRIA OF HEAT-TREATED DUPLEX STAINLESS STEELS 1 2 3 S. MAROPOULOS , A. TSOUKNIDAS , I. MELAS , D. KOUNTOURAS1, SOFIA PAPANIKOLAOU1 and XARITINI BOULGARAKI1 1Department of Mechanical Engineering University of Applied Science of West Macedonia Koila, 50100 Kozani Greece 2Laboratory for Machine Tools and Manufacturing Engineering Department of Mechanical Engineering Aristoteles University of Thessaloniki Greece e-mail: alextso@auth.gr 3Hellenic Petroleum S. A. N. Ionia, Thessaloniki 54110 Greece Abstract The decomposition of δ-ferrite to austenite has been studied in SAF2205 by using optical and electron microscopy. Heat treatment was conducted at varying temperatures and the effect of temperature on the microstructure was systematically investigated, while the cooling method was also considered as variables. It was found that the maximum amount of austenite occurs at 850°C Keywords and phrases: dual phase steels, heat treatment, austenite-ferrite equilibrium. Received October 4, 2010  2010 Scientific Advances Publishers 166 S. MAROPOULOS et al. and the precipitation of sigma phase in ferrite occurs at 980°C. Chemical analysis showed that Cr and Mo partition to the ferrite and Ni and Mn to the austenite. The results were compared with those obtained from calculations based on thermodynamic data, and it was found that the cooling medium has a significant impact the expe