A modified 1% CrMoV steel of particular use in steam and gas turbine rotors contains from about 0.20 percent to about 0.35 percent carbon, less than about 0.1 percent manganese, from about 1.5 percent to about 6.5 percent nickel, from about 0.8 percent to about 2.0 percent chromium, from about 0.9 percent to about 2.0 percent molybdenum, from about 0.1 percent to about 0.4 percent vanadium, from zero to about 0.07 percent columbium, less than about 0.12 percent silicon, less than about 0.006 percent phosphorus, less than about 0.002 percent sulfur, less than about 0.005 percent antimony, less than about 0.010 percent arsenic, less than about 0.010 percent tin, less than about 0.10 percent copper, less than about 0.010 percent aluminum, balance iron totalling 100 percent, with all percentages by weight. Selected compositions of this steel can be processed to have a 50% fracture appearance transition temperature of less than ambient temperature, and do not exhibit temper embrittlement after extended periods of elevated temperature exposure. The hardenability and creep rupture properties of the modified steel are better than, or equivalent to, those of the standard 1% CrMoV steels, which are brittle at ambient temperatures and subject to temper embrittlement.

Modified 1% CrMoV rotor steel

The present invention relates to a steam turbine comprising a rotor shaft (3) integrating high and low pressure portions provided with blades (4) at the final stage thereof having a length not less than 30 inches, wherein a steam temperature at first stage blades (4) is 530°C, a ratio (L/D) of a length (L) defined between bearings (12) of the rotor shaft (3) to a diameter (D) measured between the terminal ends of final stage blades (4) is 1.4 to 2.3. This rotor shaft (3) is composed of heat resisting steel containing by weight 0.15 to 0.4% C, not more than 0.1% Si, 0.05 to 0.25% Mn, 1.5 to 2.5% Ni, 0.8 to 2.5% Cr, 0.8 to 2.5% Mo and 0.15 to 0.35% V and, further, the heat resisting steel may contain at least one of Nb, Ta, W, Ti, Al, Zr, B, Ca, and rare earth elements.

Steam turbine rotor shaft and heat-resisting steel therefor

An alloy suitable for use in a rotor, such as one or more regions of a steam turbine rotor, as well as a forged rotor formed with the alloy. The alloy consists of, by weight, 0.20 to 0.30% carbon, 0.80 to 1.5% chromium, 0.80 to 1.5% molybdenum, 0.50 to 0.90% vanadium, 0.30 to 0.80% nickel, 0.05 to 0.15% titanium, 0.20 to 1.0% manganese, and 0.005 to 0.012% boron, the balance iron, optionally low levels of other alloying constituents, and incidental impurities.

Steam turbine rotor and alloy therefor

A low alloy steel ingot contains from 015 to 030 % of C, from 003 to 02 % of Si, from 05 to 20 % of Mn, from 01 to 13 % of Ni, from 15 to 35 % of Cr, from 01 to 10 % of Mo, and more than 015 to 035 % of V, and optionally Ni, with a balance being Fe and unavoidable impurities Performing quality heat treatment including a quenching step and a tempering step to the low alloy steel ingot to obtain a material, which has a grain size number of from 3 to 7 and is free from pro-eutectoid ferrite in a metallographic structure thereof, and which has a tensile strength of from 760 to 860 MPa and a fracture appearance transition temperature of not higher than 40 °C

Low alloy steel for geothermal power generation turbine rotor, and low alloy material for geothermal power generation turbine rotor and method for manufacturing the same

PURPOSE:To produce a heat resistant steel suitable for rotor for high temp. steam turbine, having superior high temp. strength, and maintaining the high temp. strength for a long time. CONSTITUTION:This heat resistant steel has a composition consisting of, by weight, 0.05-0.30% C, 8.0-13.0% Cr, <=1.0% Si, <=1.0% Mn, <=2.0% Ni, 0.10-0.50% V, 0.03-0.50% Ta, 0.50-5.0% W, 0.025-0.10% N, <=1.5% Mo, and the balance Fe with inevitable impurities and also has a ferrite/martensite structure. By this method, the heat resistant steel remarkably improved in high temp. creep rupture strength and creep resistance can be obtained.

Steam turbine rotor

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, 0.1W0.3% C, ≤0.25% Si, ≤1.3% Mn, 1W13% Cr, 0.4W2.0% Mo, 0.1W0.3% V, 0.02W0.3% Nb and/or Ta, ≤0.02% T.Al and the balance Fe with accompanying impurities or further contg. one or more among 0.5W4.0% Ni, ≤2.0% W, 0.02W0.05% N and 0.001W0.04% B is forged into a rotor. After the whole of the rotor is heated to 600W1,050°C, the surface part corresponding to ≥1/2 of the radius in the direction of the axial core is rapidly heated to 900W1,100°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 500W780°C to obtain a rotor having the desired characteristics. COPYRIGHT: (C)1987,JPO&Japio

Manufacture of turbine rotor

PURPOSE:To produce a heat resisting steel having an excellent creep rupture resistance characteristic by subjecting a steel contg. a specific ratio each of C, Si, Mn, P, S, Ni, Cr, Mo, etc. to heating, hot working, accelerated cooling and tempering under specific conditions. CONSTITUTION:The steel contg., by weight 5, 0.02-0.25% C, =1050 deg.C. The steel is then subjected to hot working at 850-1000 deg.C and at least at 20% cumulative draft and is then subjected to accelerated cooling at the fastest possible point of the time. The steel is further tempered at 550-750 deg.C, by which the heat resisting steel is produced. The heat resisting steel having good creep rupture strength and excellent toughness is thus obtd.

Production of heat resisting steel having excellent creep rupture resistance characteristic

PURPOSE:To improve the high temp. strength, impact properties and embrittlement resistance of the steam turbine rotor by manufacturing the turbine rotor of a specified compsn. admixed with a large amt. of Mn. CONSTITUTION:A raw material contg., by weight, 0.07 to 0.20% C, <=0.10% Si, 0.70 to 2.0% Mn, 9 to 12% Cr, <=1.5% Ni, 0.4 to 1.8% Mo, 0.01 to 0.1% Nb, 0.1 to 0.3% V and 0.01 to 0.1% N, furthermore contg., at need, <=2% W and the balance iron with inevitable impurities is melted in an electric furnace to prepare an ingot having low Si content by a VCD method. The ingot is forged into turbine rotor stock, which is subjected to soln. treatment at about 1000 to 1130 deg.C, is thereafter subjected to oil quenching and is furthermore subjected to two stage tempering treatment of primary one at about 500 to 600 deg.C and secondary one at about 620 to 720 deg.C. In this way, the steam turbine rotor having high toughness and stabilized long time embrittlement properties can be obtd.

PURPOSE: To manufacture heat resisting rotor having reduce embrittlement due to a long time heating without lowering high temp. strength and creep rupture strength, by specifying contents of C, Cr, Mo, V, Nb, etc., in steel compsn., and applying heating, accelerated cooling and reheating to the rotor under suitable conditions after forming to rotor. CONSTITUTION: Rotor is formed by using steel composed of, by weight 0.15W0.25% C, ≤0.10% Si, ≤0.30% Mn, 9W13% Cr, ≤1.0% Ni, 1W3% Mo, 0.15W0.30% V, 0.02W0.07% Nb, ≤0.015% P, ≤0.010% S, ≤0.015% Al, ≤0.0035% Sb+Sn and the balance Fe with inevitable impurity. The rotor is heated to 1,000W1,100°C, then acceleratedly cooled, next reheated to ≥600°C. If necessary, 0.001W0.004% Ca or further suitable quantities of one kind or more among B, W, N are added to the steel compsn. By this method, heat resisting rotor of a little deterioration in toughness even by long time heating is obtd. COPYRIGHT: (C)1987,JPO&Japio

Manufacture of heat resisting rotor

PURPOSE:To produce a heat resistant rotor minimal in long time heating embrittlement under high temp. steam conditions and improved in high temp. strength and creep rupture strength by regulating contained components. CONSTITUTION:A steel, having a composition consisting of, by weight, 0.07-0.18% C, <=1.0% Si, <0.1% Mn, 10-13% Cr, 0.1-1.0% Ni, 0.1-1.0% Mo, 0.15-0.40% V, 0.02-0.1% Nb, 2.0-4.0% W, 3.0-8.0% Co, <=0.010% P, <=0.010% S, <=0.015% Al, 0.0005-0.005% B, 0.01-0.1% N, <=0.007% Sb+Sn, and the balance essentially Fe and containing if necessary, <=0.1% Cu, is hot-formed, heated to 1020-1120 deg.C, cooled acceleratedly, and reheated to a temp. between 700 deg.C and the Ac1 point, by which the heat resistant rotor can be produced.

Moriyama Yasushi

Papers

Manufacture of turbine rotor

Production of heat resisting steel having excellent creep rupture resistance characteristic

Steam turbine rotor

Manufacture of heat resisting rotor

Production of heat resistant rotor