| 摘要 |
PURPOSE:To obtain a rotor having satisfactory creep rupture strength and superior toughness by forging a Cr-Mo alloy steel having a regulated composition and by heating and tempering it under specified conditions. CONSTITUTION:An alloy steel consisting of, by weight, 0.1-0.3% C, <=0.25% Si, <=1.3% Mn, 1-13% Cr, 0.4-2.0% Mo, 0.1-0.3% V, 0.02-0.3% Nb and/or Ta, <=0.02% T.Al and the balance Fe with accompanying impurities or further contg. one or more among 0.5-4.0% Ni, <=2.0% W, 0.02-0.05% N and 0.001-0.04% B is forged into a rotor. After the whole of the rotor is heated to 600-1,050 deg.C, the surface part corresponding to >=1/2 of the radius in the direction of the axial core is rapidly heated to 900-1,100 deg.C to produce a temp. difference in the radial direction and accelerated cooling is carried out without leveling the difference. The rotor is then tempered at 500-780 deg.C to obtain a rotor having the desired characteristics.
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