Study on the Heat Treatment Process of SXQ500/550DZ35 Steel QLT for the Seat Ring and Guide Vane of a Hydropower Station

Because steel plates of 150~300 mm cannot reach the ideal cooling rate under the industrial cooling condition, the development of a super thick plate for the seat ring and guide vane of hydropower stations cannot be successful. In this paper, the influence of the original microstructure and the quenching temperature on the austenite grain size and the analysis of the quenching temperature on the austenite transformation amount were carried out through experiments. The effect of quenching temperature on the content of austenite carbon was calculated by a phase diagram, and then the effect of quenching temperature on the cooling characteristics of the steel was simulated by JMatPro, and the microstructure changes and performance advantages of the QLT heat treatment process were studied and analyzed. Finally, the QLT heat treatment process of SXQ500/550DZ35 steel for the seat ring and guide blade of hydropower stations was researched and formulated (925 °C + 830 °C + 640 °C), and the heat treatment process optimization of a thick steel plate under insufficient cooling conditions during industrial production was solved.