Welding repair process method for cast steel kettle rings of autoclaved kettle and cover edge cracks

Abstract

The invention discloses a welding repair process method for cast steel kettle rings of an autoclaved kettle and cover edge cracks. The method comprises the following steps of: 1) cleaning up the kettle rings and the surfaces of the cover edge tooth roots, performing nondestructive inspection, finding out all the crack parts, and polishing and eliminating the positions where the cracks are; 2) before welding, locally heating a welding repair region to about 200 DEG C by using a heating device; 3) during welding, performing carbon dioxide gas protective welding by adopting small welding line energy, high welding speed, thin layers and multi-channel welding and controlling the interpass temperature to be between 250 and 300 DEG C; and 4) preserving heat after welding, namely performing tightheat preservation on a repair welding part by using heat-preserving cotton at once after welding, naturally cooling to room temperature, and then removing the heat-preserving cotton. The welding repair process technique is stable; cost is low; economic and social benefits are remarkable; the domestic leading level is reached; and a wide popularization and application prospect is achieved.

Description

technical field [0001] The invention relates to a welding repair process method, which belongs to the technical field of metal material welding, in particular to a welding repair process method for cracks in autoclave cast steel kettle rings and lid edges. Background technique [0002] At present, the autoclave is widely used in the industrial production in our country. Because it is a quick-opening door design, the autoclave is sealed by the meshing and sealing of the kettle ring and the lid edge teeth at both ends. The kettle ring and cover edge are usually made of cast steel. The material grade is ZG230-450H. During casting, defects such as pores, blisters, and looseness are prone to occur. The working pressure of the autoclave is relatively high. Under the action of alternating loads, the autoclaved The kettle cast steel kettle ring and cover edge are extremely prone to fatigue cracks at the above-mentioned defects. [0003] For the treatment of cracks on the kettle rin...

AI Technical Summary

Problems solved by technology

The kettle ring and cover edge are usually made of cast steel. The material grade is ZG230-450H. During casting, defects such as pores, blisters, and looseness are prone to occur. The working pressure of the autoclave is relatively high. Under the action of alternating loads, the autoclaved The cast steel kettle ring and cover edge are very prone to fatigue cracks at the above defects

[0003] For the treatment of cracks on the kettle ring and cover edge, there are only two solutions at present: one is to buy a new autoclave, and the other is to replace the autoclave kettle ring and cover edge; Smaller, but the cost of the autoclave is high, at least hundreds of thousands or even over a million, the cost is high

The latter is due to the long maintenance time, and the same defect may appear soon, and the enterprise will cause huge losses due to the suspension of production.

[0004] Therefore, qualified professional maintenance manufacturers and manufacturers have tried to use welding methods for repairs, but due to improper welding processes, new cracks often appear in the welds and heat-affected zones and cannot be completely repaired. In severe cases, the equipment will be scrapped directly. never been successful

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