Preparation and surfacing methods of nuclear-grade valve surfacing material

Abstract

Preparation and surfacing methods of nuclear-grade valve surfacing material belong to the field of metal materials. Alloy powder composed of, by weight, (3-5)% of Fe, (23-27)% of Ni, (1-2)% of Cr andC is prepared by means of atomization; the alloy powder having particle size of 30-80 mu m is mixed with BC powder having particle size of 1-5 mu m, V power having particle size of 5-10 mu m, Ti powerof 5-10 mu m and Mo powder of 5-10 mu m to obtain surfacing powder; the surfacing powder is melted on a valve base by means of laser-cladding surfacing; in the following cooling process, (Fe, Cr)B2,TiC, (Fe, Cr)23C6 and (Mo, V)23C6 composite strengthening phases may be successively formed in the Fe-Ni-Cr base; these strengthening phases help greatly improve hardness and wear resistance of alloy;particularly, at 360 DEG C, the wear resistance is higher than that of existing cobalt-based stellite; the base has excellent corrosion resistance, and it is ensured that surfaced alloy has high hardness and wear resistance both at room temperature and high temperature.

Description

technical field [0001] The invention belongs to the field of metal materials, and relates to a preparation of a nuclear-grade valve surfacing material and a surfacing method. Background technique [0002] Nuclear power valves are important key components of nuclear power equipment. The common method of strengthening nuclear valves is surface treatment of sealing surfaces, that is, selecting surfacing materials with better performance than nuclear valves, and forming a surfacing sealing surface on the surface of nuclear valves, which can significantly prolong the service life of the valves. service life. This not only significantly improves the working performance of the nuclear valve, but also saves a lot of precious alloy materials. The quality of the sealing surface material and surfacing welding is directly related to the service life of the valve and the safety and reliability of production. At present, the sealing surface of nuclear power valve seat is made of cobalt-...

AI Technical Summary

Problems solved by technology

However, there are two outstanding problems in the selection of cobalt-based alloys: one is that the wear or corrosion debris generated by the cobalt-based alloy sealing surface during the working process contains Co59 elements, which will form isotope Co60 when excited by the nucleus, and Co60 will prolong nuclear radiation. The half-life period of the reactor increases the time for shutdown and maintenance, and increases the difficulty and cost of nuclear shielding; second, my country is a country with scarce cobalt resources, and the extraction process of cobalt metal is complicated and the recovery rate is low

Therefore, in view of the design concept of the fourth-generation nuclear power plant, it has become an inevitable trend to use cobalt-free alloys as sealing surface surfacing materials. At present, there is no mature cobalt-free alloy for surfacing welding of nuclear power valves.