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|1. (WO2017037804) METHOD FOR PRODUCING TURBINE ROTOR AND METHOD FOR PRODUCING TURBINE|
|Applicants:||MITSUBISHI HEAVY INDUSTRIES COMPRESSOR CORPORATION
JAPAN CASTING & FORGING CORPORATION
|Title:||METHOD FOR PRODUCING TURBINE ROTOR AND METHOD FOR PRODUCING TURBINE|
This method for producing a turbine rotor (30) comprises: a shaping step (ST1) in which a base rotor material (30A) having a maximum outer diameter of at most 1000 mm is shaped from a low-alloy steel containing, in weight%, 0.20-0.35% of carbon, at most 0.35% of silicon, at most 1.00% of manganese, 0.50-1.50% of nickel, 2.00-2.50% of chromium, 0.90-1.50% of molybdenum, and 0.20-0.30% of vanadium; a quenching step (S2) in which the base rotor material (30A) is heated in a temperature range of 940-960°C, and then subjected to oil quenching at least in a temperature range of 250-500°C, at a cooling rate of 2.0°C/min or higher; and a tempering step (S3) in which, following the quenching step (S2), the base rotor material (30A) is subjected to tempering in a temperature range of at least 630°C and under the condition that a tempering parameter P as defined by the equation P=T(C+logt) (where T represents an absolute temperature (K), t represents time (h), and C represents a material constant) falls between 19700 and 19900.