Nuclear main pump centering block laser cladding cobalt-based alloy powder welding method

Abstract

The invention relates to a nuclear main pump centering block laser cladding cobalt-based alloy powder welding method. The method is characterized in that a centering block base material is martensitic stainless steel with the Euro sign number of EN10088-31.4313+QT780, martensite is quenched, tempered and tempered, and the surface of a surfacing layer needs to be wiped, deoiled and derusted by acetone or alcohol before laser cladding; adopted laser cladding cobalt-based alloy powder meets the AWS 5.21ERCoCr-A standard requirements, and in addition, the Fe content needs to be 0-2.5%. According to the method, centering block cobalt-based alloy powder surfacing is effectively achieved, and the welding defects that during traditional manual tungsten electrode inert gas shielding electric arc surfacing, the efficiency is low, the melting depth is small, the dilution rate is large, the heat input amount is large, the workpiece deformation amount is large, the welding quality stability is poor, air holes appear easily and the like are effectively overcome. The whole surfacing process does not need to be operated by a welding operator, only a molten pool needs to be observed, the working environment of the welding operator is greatly improved, and meanwhile, automatic welding is easily achieved. Under the condition that the same performance requirement is met by laser cladding, the cladding thickness is reduced, the cost is saved, and the surfacing efficiency is improved.

Description

Technical field: [0001] The invention relates to a laser cladding cobalt-based alloy powder welding method for a centering block of a nuclear main pump. Background technique: [0002] The nuclear reactor coolant pump (referred to as the main pump) is the "heart" equipment of the nuclear power plant reactor and the only rotating mechanical equipment in the reactor cooling system. One of the basic requirements for it is: it can work safely and reliably without maintenance for a long time. As the key part of the main pump, the centering block is also the connecting part of the lower guide bearing and the bearing guide ring. It is necessary for the centering block to have good performance requirements such as wear resistance and fatigue resistance, so the quality of the surfacing welding of the centering block is critical. Very demanding. Therefore, laser cladding cobalt-based alloy powder surfacing welding centering block is a very necessary and practical technology. [0003]...

AI Technical Summary

Problems solved by technology

[0003] The base material of the centering block is martensitic stainless steel European standard EN10088-31.4313+QT780. The martensite has been quenched, tempered and tempered. It has high strength and good wear resistance, but it is easy to produce cold cracks during welding.

[0004] At present, manual tungsten inert gas shielded arc welding is usually used for surfacing centering blocks in the world. This method has low welding efficiency, shallow penetration, large dilution rate, large heat input, large workpiece deformation, poor welding quality stability, and prone to pores. Welding defects such as welding defects, and the welder's operating environment is relatively harsh, so the improvement of the centering block surfacing welding method is of great significance

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