Advanced steelmaking equipment and processes that are state of the art for the production of rotor forgings are described. The Electric Power Research Institute (EPRI) has sponsored a study on high-pressure (HP) rotor forgings of 1Cr-Mo-V steel with 0.001 to 0.002% sulfur content produced by conventional vacuum carbon deoxidation (VCD) and electroslag remelting processes. Low phosphorus, low hydrogen, and residual element control were also objectives of this study.

Laboratory studies show that combined low levels of manganese (Mn), phosphorus (P), silicon (Si), and residual elements improve the toughness and resistance to temper embrittlement of rotor steels. In a recent EPRI program with Vereinigte Edelstahlwerke, the process combination basic electric arc furnace melting and ladle furnace refining with vacuum treatment successfully produced a 25-metric-ton model rotor in which levels of 0.02Mn, 0.002P, 0.001S, 0.04Si, and 0.005Al at 27 ppm oxygen were achieved.

Specification implications of these trends to high-purity rotor steels suggest that requirements for Mn, Si, and sulfur (S) will trend to lower content levels.