Formation of Laves phase in creep strength enhanced ferritic steel is investigated using re-austenitization and tempering treatment. The as-received material is exposed to 620°C for 4560 h aging, and then re-austenitizated at 1050°C for 1 h, and followed by tempering at 760°C for different times (2 and 4 h). After re-austenitization and tempering, the dissolution of Laves phase is observed while grain size and microhardness have not changed significantly. A model is suggested to quantify the dissolution of W-containing Laves phase. Thermo-Calc is used to predict driving forces for precipitation of Laves and M23C6 phases.
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