Heat engine plant A335P92 steel welding technique

Abstract

The invention discloses a technology for welding A335P92 steel in a heat-engine plant, wherein, welding material adopted is Thyssen welding material or Oerlikon welding material, and welding method is manual arc welding or submerged arc automatic welding. The welding technology adopted is that: when the manual arc welding is adopted, Phi 3.2 welding rods are used for welding with the total of 15 layers and 76 passes and the average thickness of each welding deposit is 2.0mm; when the submerged arc automatic welding is adopted, Phi 3.0 welding rods are adopted for welding with the total of 10 layers and 16 passes and the average thickness of each welding deposit is 3.0mm; the tempering parameter value of heat treatment on welding positions ranges from 21.3 to 21.6.

Description

technical field [0001] The present invention relates to the design and manufacture technology of pipe fittings for generating sets in thermal power plants, especially to the welding and heat treatment technology for pipe fittings using A335P92 steel in supercritical generating sets, so as to ensure that the welding quality of piping meets the requirements for use in the piping of ultra-supercritical generating sets . Background technique [0002] The characteristics of my country's energy structure determine that the development of my country's electric power industry mainly depends on thermal power units, and the development of large ultra-supercritical units is an inevitable choice for the development of thermal power units. The development and application of heat-resistant alloy steel with better thermal strength and oxidation resistance is one of the key technologies for the development of high-efficiency ultra-supercritical thermal power generation units. The developme...

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Problems solved by technology

[0022] (2) P92 steel welding has obvious aging tendency

[0024] (3) The reason why the weld toughness is lower than that of the base metal

[0025] The reason why the toughness of the weld metal is not as good as that of the base metal is that the weld metal is a cast structure cooled from a very high temperature molten state. It has no chance to go through the TMCP process (Thermal-Mechanical Control Process), that is, the heat-controlled rolling process, and the grains are obtained. Before refining, the microalloying elements such as Nb are still solid-fused in the matrix, and there is no chance to fully analyze the reason

[0026] (4) Welded joints are the weakest link that affects the safety of unit operation. Due to the high content of alloy elements in P92 steel, there are greater technical difficulties in welding, which are prone to low impact energy of joints and early failure of Type IV cracking during long-term operation. If If the welding quality is not guaranteed, the advantages of P92 will no longer exist, and it will pose a threat to the safety of unit operation

However, the research on the welding process of P92 steel is still in its infancy. In order to ensure the factory processing and manufacturing quality of P92 steel components in ultra-supercritical unit power plants, it is necessary to carry out experimental research on the welding process of P92 steel factory piping.

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