2022 年 62 巻 4 号 p. 733-739
Austenite phase growth behavior in continuous cooling process from high temperature in the 25%Cr and 22%Cr duplex stainless steels was investigated regarding various cooling rate conditions. The ratio of ferrite and austenite phase is very important factor to obtain the maximum performance such as toughness and corrosion resistance of the steels. However, the fraction of austenite phase in the heat affected zone (HAZ) in weldments can be changed in the portion closed to fusion boundary during welding process. In that portion the fraction of austenite phase is influenced by the welding condition as well as by the chemical composition in steels.
The way to predict that fraction in the continuous cooling was investigated applying the additivity rule to the physical model proposed regarding austenite phase growth during isothermal heating by the authors in another work. The measurement of austenite phase fraction was conducted experimentally in the specimens after continuous cooling from 1653 K employing 25%Cr or 22%Cr duplex stainless steels and the effect of cooling rate on that fraction was obtained. It was clarified the above-mentioned calculation results of austenite phase fraction in various cooling rate had good fit to the experimental data.
