Material repair welding method of CB2 casting of ultra-supercritical turbine unit

Abstract

The invention discloses a material repair welding method of a CB2 casting of an ultra-supercritical turbine unit. The method comprises the following steps that firstly, high-temperature softening tempering preheating is carried out; secondly, nondestructive inspection is carried out; thirdly, flaws are eliminated; fourthly, the portions where the flaws are eliminated are preheated; fifthly, a welding material which is the same as and cooperates with a base material is used for performing repair welding; sixthly, post-heating is carried out on the repair welding area; seventhly, nondestructive inspection is carried out on the repair welding area; eighthly, the austenitizing temperature is achieved through heating and then preserved, the cooling speed of the CB2 casting is controlled after heat preservation is finished, after the room temperature is achieved through cooling, high-temperature tempering is performed when the temperature of the casting is raised to about 100 DEG C below a point AC1 of a CB2 material, and the cooling speed is controlled for achieving the room temperature after heat preservation is finished; and ninthly, the nondestructive inspection is carried out. The procedures that the repair welding is carried out firstly, and then the performance thermal treatment is carried out are adopted, it can be ensured that the same performance thermal treatment process is adopted in the repair welding area and a body area, and it is guaranteed that the performance of a welding line joint and the performance of a body are basically consistent.

Description

technical field [0001] The invention relates to a large CB2 casting of an ultra-supercritical steam turbine unit, in particular to a material repair welding method for a CB2 casting of an ultra-supercritical steam turbine unit. Background technique [0002] With the development of steam turbine technology in the direction of high parameters and large capacity, the temperature and pressure of steam are further increased. A newly developed material CB2 (ZG12Cr9Mo1Co1NiVNbNB) used in valves and cylinders of ultra-supercritical units has significantly increased the types and contents of alloy elements, especially It is to add Co, N, B elements to improve its high temperature creep resistance performance, which increases the difficulty of one-time qualified casting of CB2 large castings, and there are many rework welding situations. [0003] Cylinders and valve castings of steam turbine units usually use high-temperature quenching + tempering for performance heat treatment first,...

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Problems solved by technology

[0004] The purpose of the present invention is to solve the above-mentioned technical problems, to provide a method for repair welding of CB2 casting materials of ultra-supercritical steam turbine units, to solve the problem of repeated repair welding of the material casting products, and the difference in mechanical properties between the casting body and the repair welding area after repair welding. big problem

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