A Surfacing Welding Method for Stainless Steel Castings with Controlled Depth of Penetration

Abstract

The invention discloses a stainless steel casting surface overlaying method for controlling the fusion depth. The method includes the following steps that firstly, the outer side wall and the inner side wall of a connecting pipe are each provided with an extension ring in a spot welding mode; secondly, 100% of penetrant testing is performed on the welding points of the extension rings; thirdly, a plurality of layers of overlaying is performed on the connecting pipe through a hot wire tungsten inert gas arc automatic welding method so that an overlaying layer can be formed; fourthly, after overlaying is completed, the overlaying layer is polished, and the extension rings on the outer diameter side and the inner diameter side of the connecting pipe are removed. According to the method, after austenitic stainless steel materials low in sulphur content are adopted for performing overlaying on a pump case surface to be subjected to butt joint, a nickel-base alloy isolation layer welding mode is adopted, and the situation that when pump case casting stainless steel is directly welded to a nickel-base alloy isolation layer, the defect of heat cracks or micro cracks is easily caused can be avoided.

Description

technical field [0001] The invention relates to a surfacing welding method, in particular to a surface surfacing welding method for controlling penetration depth of stainless steel castings. Background technique [0002] After the surfacing welding of the nickel-based alloy isolation layer of the outlet of the lower head of the nuclear steam generator is completed, it needs to be connected with the main pump casing of the reactor coolant. The pump casing material of the main pump is cast stainless steel SA351CF8A, the sulfur content in the base metal is higher than 0.010%, and it is easy to produce thermal cracks or micro cracks when welding with the nickel-based alloy isolation layer. The present invention provides a method to prevent such defects from occurring. The welding method, that is, after the austenitic stainless steel material with a sulfur content of less than 0.002% is used for surfacing welding on the surface of the pump casing to be connected, it is then welde...

AI Technical Summary

Problems solved by technology

Due to the relatively loose structure of the casting material and the existence of defects such as local pores, it is difficult to overlay welding on the surface of the pipe. These local pores and porosity in the base metal are melted and aggregated or expanded during the welding process, resulting in the surfacing layer and the base metal. Defects such as unfused and pores appear in the fusion area

Images