Modeling of effects of temperature and alloying elements on austenite phase growth rate in duplex stainless steel

Abstract

The growth rate of austenite phase from overcooled ferrite phase in duplex stainless steel was investigated to clarify the quantitative effects of temperature and chemistry in isothermal heating process. The proper fraction of ferrite and austenite phase is very important to obtain the maximum performance such as toughness and corrosion resistance of the steels. However, the fraction in heat affected zone (HAZ) in weldments can be changed during welding process. A physical model of growth rate as function of temperature including the parameter regarding chemistries was suggested. The measurement of austenite phase conducted experimentally after isothermally heated at various temperature, employing 25%Cr or 22%Cr duplex stainless steels containing various level of nitrogen. Referring those data obtained, it was confirmed that the effects of temperature and chromium and nitrogen contents on the growth rate is explained by the physical model suggested in this work.