Welding method of nickel-base alloy steel pipeline

Abstract

The invention discloses a welding method of a nickel-base alloy steel pipeline. A groove of a pipeline to be welded is treated, the angle of the groove of the pipeline to be welded is 70-75 degrees, the poor mobility of material liquid metal is avoided, the groove of the pipeline to be welded and the outer surface of the pipeline to be welded are polished and cleared, the situation that an oxidization layer exists on a weld opening is prevented, then after the pipeline is located and fixed, argon is adopted for protecting the groove of the pipeline to be welded, layering welding is adopted, and the situation that due to the improper welding temperature, as a result, metal grain of weld seams is thick and large, and the mechanical performance and corrosion resisting performance of the weldseams are lowered. According to the method, the scheme is reasonable, the data is reliable and explicit, the problem of 800 H welding quality can be effectively solved, the welding quality is improved, a left gas blocking baffle, a right gas blocking baffle and the inner wall of the pipeline to be welded are utilized for forming a sealing structure, then multiple gas output holes in a gas conveying pipe are utilized for inflating argon into the weld opening, the stable argon environment atmosphere is provided for welding, the device is simple in structure, and stability of the welding environment is ensured.

Description

technical field [0001] The invention belongs to the field of welding technology, and in particular relates to a nickel-based alloy steel pipeline welding method. Background technique [0002] UNS N08810 is an American standard ASTM B409 equivalent to Incoloy 800H, which is a nickel alloy Ni-Fe-Cr system (referred to as 800H pipe), which has typical corrosion resistance and high temperature oxidation resistance, especially at a high temperature of 1000 °C. Corrosion, heat fatigue resistance, high temperature impact resistance, in the case of solid solution, it has excellent pressure crack resistance characteristics, in industrial furnaces and petrochemical industries, it is widely used in various high temperature and high pressure environment outlet headers and transmission pipelines etc. structure. [0003] At present, domestic 800H pipes (nickel-based alloy steel pipes) are mainly used in aerospace and petrochemical equipment, and the caliber is mainly DN15. However, larg...

AI Technical Summary

Problems solved by technology

Therefore, the welding and installation technology of nickel-based alloy steel pipes involved in China is rarely used. There is no 800H pipe welding construction technology, and the welding of 800H pipes cannot be realized by using the existing technology. Knowing from the chemical composition (%) of UNS N08810 alloy, Ni The content of NiO accounts for 32.0%, and it has a high-Ni matrix that can dissolve high corrosion-resistant elements, so that the alloy has poor fluidity in the molten pool metal during welding, and a refractory oxide film (NiO) is easily formed on the surface, making penetration Poor performance, the weld is easy to form sundries, resulting in welding thermal cracks

At the same time, due to the relatively poor fluidity of the liquid metal in the nickel alloy weld, the cooling rate of the weld metal is relatively fast, so that the gas in the molten pool has no time to escape, resulting in pores, and the solubility of oxygen, carbon dioxide and hydrogen in liquid nickel It is also relatively large, and the solubility decreases significantly when cooled, thereby forming pores

At present, in the welding process, inert gas protection is used locally, and the existing inert gas delivery device cannot ensure the inert gas at the welding joint is sufficient, and it is easy to cause waste of inert gas

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