A heat treatment method for rotors of steam turbines at 620°C and above

Abstract

The invention discloses a heat treatment method for a rotor of a steam turbine with a grade of 620°C and above, and belongs to the technical field of steam turbines with a grade of 620°C and above. A heat treatment method for a rotor of a steam turbine with a grade of 620°C or higher according to the present invention, the rotor includes a high-temperature section and a low-temperature section, and the heat treatment method includes the following steps: Quenching: the entire rotor is heated to 1070°C-1080°C, the holding time is 16h-24h, and then Transfer to quenching medium for cooling; first tempering: heat the entire rotor to 570°C-580°C, hold for 20h-26h, and then take it out of the furnace to cool; second tempering: set a heat insulation baffle between the high temperature section and the low temperature section , so that it is separated and heated by heat insulation. The low-temperature section is heated to 730-830°C, and the high-temperature section is heated to 650-730°C. The holding time is 20h-26h, and then it is cooled out of the furnace. The rotor treated by the heat treatment method of the present invention can be used in a steam turbine with a temperature parameter of 620°C and above, which can not only meet the high-temperature strength requirement in the temperature range of 620°C and above, but also meet the ductile-brittle transition temperature requirement of the shaft seal section.

Description

technical field [0001] The invention relates to a rotor of a steam turbine with a grade of 620°C and above, in particular to a heat treatment method for a rotor of a steam turbine of a grade of 620°C and above, belonging to the technical field of steam turbines of a grade of 620°C and above. Background technique [0002] In order to further save energy and reduce consumption, modern thermal power steam turbine units have been working hard to improve the steam parameters of the unit, so as to improve the efficiency of the unit. my country's ultra-supercritical steam turbines are relatively mature. At present, 620°C class steam turbines have been put into commercial operation, and more than 620°C class has been launched. Research on steam turbine technology. However, with the continuous improvement of the main steam parameters of steam turbines, the requirements for the high-temperature and long-term durability of the rotor continue to increase, and the research and development...

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Problems solved by technology

[0005] At present, there is no reasonable method to solve the safety problem caused by the high FATT50 of the shaft seal position in the low-temperature section under the premise of meeting the high-temperature strength requirements of the design for the high-temperature section of the rotor.

That is, for large rotor forgings under high-temperature working conditions, there is no reasonable method to meet the two requirements of the design on the performance of the rotor at the same time: a. The high-temperature section of the rotor has a durable fracture strength of ≥ 100 MPa for 100,000 hours at high temperature; b. Shaft seal position (low temperature section of rotor) FATT50≤120℃

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