1990 Volume 76 Issue 7 Pages 1163-1170
To develop a new low alloy steel for high pressure-low pressure mono-block steam turbine rotor, considerable studies have been performed.
The targets of the new low alloy rotor steel development are to have same high temperature strength as those of conventional 1CrMoV steel for high pressure side of rotor, and to have excellent both room temperature strength (Yield strength is higher than 70 kgf/mm2) and fracture toughness (FATT is lower than + 80°C) for low pressure side of rotor.
The effects of alloy composition on mechanical properties and the heat treatment characteristis of low alloy were investigated. As a result, the 21/4 CrMoV steel containing low silicon manufactured by vacuum carbon deoxidization process was found to show the best performance for mono-block steam turbine rotor.
The 21/4 CrMoV steel rotor for mono-block steam turbine was produced by commercial base. Tensile, impact, stress rupture and metallurgical test were conducted on this rotor, and it is confirmed that this rotor has excellent yield strength and impact propertis at low pressure side and good stress rupture strength at high pressure side.
