Effect of austenitization temperature on phase transition features of high Cr ferritic heat-resistant steel

摘要

The phase transformation of high Cr ferritic heat-resistant steel has been investigated by using differential scanning calorimeter and predicted by Thermo-calc calculation. The steel specimens were hot rolled and followed by air cooling, and then heated from room temperature up to different austenitization temperature as 800°C, 900°C, 1000°C and 1100°C. The DSC curves during heating process showed that the magnetic transition temperature and the Ac1 temperature are 744.9°C and 850.9°C, respectively. The austenitization range was about 58°C. The onset and offset temperature of martensite transformation both increase with the increase of austenitization temperature. The experimental results and the Thermo-calc calculated results both displayed that M_(23)C_6 carbides precipitated at around 950°C, and δ-ferrite started to form at about 1020°C.