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Ultra-pure alloy and method for manufacturing turbine rotor forging by using same

A steam turbine rotor and rotor body technology, applied in the manufacture of tools, quenching agents, heat treatment equipment, etc.

Active Publication Date: 2011-11-09
宝武特种冶金有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although no harmful elements such as S, P, As, Sb, Sn and the control range of N, H, and O content have been found in the low-pressure rotor materials found recently, the elements of Cr, Ni, Mo, V, Mn, and Si are especially The contents of Mn and Si are equivalent to domestic 30Cr1Mo1V and 30Cr2Ni4MoV alloys, which are commonly used NiCrMoV alloys, and can only be used to produce low-pressure rotors with operating temperatures below 350 °C

Method used

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  • Ultra-pure alloy and method for manufacturing turbine rotor forging by using same
  • Ultra-pure alloy and method for manufacturing turbine rotor forging by using same
  • Ultra-pure alloy and method for manufacturing turbine rotor forging by using same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0051] The chemical composition mass percent of the alloy material in this example is: C: 0.28; Mn: 0.024; Si: 0.016; P: 0.002; S: 0.004; Cr: 1.65; Ni: 3.75; : 0.04; Al: 0.003; Sn: 0.004; Sb: 0.0010; As: 0.006; O≤35ppm, H≤1.0ppm, N≤80ppm; the rest are Fe and unavoidable impurities.

[0052] Select Fe, Cr, Mo, Ni, V-Fe and other raw materials with low S, P, As, Sb, Sn and other impurities, smelt alloys in EAF (electric arc furnace) + LF (refining furnace), add Al, lime, fluorescent Stone and other materials, and ensure a certain amount of decarburization during the oxidation period, fully dephosphorize, degas, and remove inclusions, fully deoxidize and desulfurize during the reduction period, and control Mn, Si≤0.05% and S, P≤0.03% by furnace analysis before the furnace. As, Sb, Sn≤0.005%, Al≤0.02%; slag flow + slag removal at least twice before tapping, add Cr, Mo, Ni, V-Fe, adjust each alloy element to reach the above composition content; refining outside the furnace ( LF), ...

Embodiment 2

[0057] The mass percent of the chemical composition of the alloy material in this example is: C: 0.28; Mn: 0.023; Si: 0.017; P: 0.002; S: 0.004; Cr: 1.64; Ni: 3.75; : 0.039; Al: 0.003; Sn: 0.004; Sb: 0.0010; As: 0.006; O≤35ppm, H≤1.0ppm, N≤80ppm; the rest are Fe and unavoidable impurities.

[0058] The vacuum degassing time is 28 minutes; the forging heating temperature is 1200°C; the forged rotor body is hydrogen-expanded and annealed, the first stage is heated at 925°C for 15 hours and air-cooled, and the second stage is heated at 660°C for 105 hours and slowly cooled; The finished rotor required for machining after the overall heat treatment of the forging, the finished rotor required for machining after the overall heat treatment of the forging, the heat treatment process of the forging is 860°C / 5h / water quenching+580°C / 20h / furnace cooling. Others are the same as embodiment 1.

Embodiment 3

[0060] The mass percent of the chemical composition of the alloy material in this example is: C: 0.31; Mn: 0.025; Si: 0.016; P: 0.002; S: 0.003; Cr: 1.69; Ni: 3.80; : 0.04; Al: 0.004; Sn: 0.004; Sb: 0.0011; As: 0.005; O≤35ppm, H≤1.0ppm, N≤80ppm; the rest are Fe and unavoidable impurities.

[0061] The vacuum degassing time is 30 minutes, and the forging heating temperature is 1170°C; the forged rotor body is hydrogen-expanded and annealed, the first stage is heated at 900°C for 15 hours and air-cooled, and the second stage is heated at 660°C for 105 hours and slowly cooled; The finished rotor required for machining after the overall heat treatment of the forging, the finished rotor required for machining after the overall heat treatment of the forging, the heat treatment process of the forging is 850°C / 6h / water quenching+600°C / 16h / furnace cooling. Others are the same as embodiment 1.

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Abstract

The invention provides an ultra-pure alloy which comprises the following chemical components in percentage by weight: 0.26-0.37 of C, less than or equal to 0.06 of Mn, less than or equal to 0.06 of Si, less than or equal to 0.006 of P, less than or equal to 0.003 of S, 1.4-2.4 of Cr, 3.0-4.5 of Ni, 0.15-0.8 of Mo, 0.05-0.25 of V, less than or equal to 0.12 of Cu, less than or equal to 0.006 of Al, less than or equal to 0.008 of Sn, less than or equal to 0.0017 of Sb, less than or equal to 0.008 of As, less than or equal to 35ppm of O, less than or equal to 1.0ppm of H, less than or equal to 80ppm of N and the balance of Fe and inevitable impurities. The invention also provides a method for manufacturing a turbine rotor forging by using the alloy. In the method, the obtained low-pressure rotor forging can bear the work environments with the temperature of above 400 DEG C and high stress for a long term through improvement of the existing electric furnace smelting and forging technology.

Description

technical field [0001] The invention relates to the technical field of manufacturing alloy structural steel and its forgings, in particular to an ultra-pure medium-carbon low-alloy high-strength steel for a low-pressure rotor body forging of a marine steam turbine, and a method for manufacturing the forging of the rotor body. Background technique [0002] The steam turbine rotor is one of the most important key components in the steam turbine. It is responsible for the transmission of power. It is under high temperature, high pressure and high stress working conditions, and the working environment is very harsh. Therefore, it requires: 1. Uniform material composition; 2. Residual and impurity elements 3. It has good mechanical properties, plasticity, fatigue properties, durability, creep properties, corrosion resistance, processing properties, etc. [0003] According to the usage conditions, steam turbine rotors are divided into high and medium pressure rotors and low pressu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/60C22C38/46C21C7/06C21C7/064C21C7/10C21D1/26C21D1/60
Inventor 吴江枫陈新建张甫飞陆青林
Owner 宝武特种冶金有限公司
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