Welding process for corrosion-resistant alloy material Monel 400

Abstract

The invention discloses a welding process for a corrosion-resistant alloy material Monel 400. The welding process is characterized by comprising the following steps of: machining a welding part of a welding parent metal into a V-shaped groove, and performing assembly welding in a butt joint form; firstly forming manual argon tungsten-arc welding backing weld, and then protecting a welding line by using inert gas such as argon; sequentially forming the first manual arc welding filler welding and the second manual arc welding filler welding on the manual argon tungsten-arc welding backing weld; and finally, respectively forming the positive cosmetic welding and back cosmetic welding by employing manual arc welding. According to the process, the defects of hot crack, intergranular corrosion and the like during Monel 400 alloy welding are effectively overcome, the mechanical performance and service performance of the welding line are guaranteed, and the efficiency of a welding workpiece is improved.

Description

technical field [0001] The invention relates to the technical field of special corrosion-resistant alloy welding, in particular to a Monel 400 alloy welding process suitable for hydrofluoric acid corrosion resistance. Background technique [0002] Monel 400 is a nickel-based copper alloy. Its structure is a high-strength single-phase solid solution with excellent corrosion resistance. This alloy is one of the few fluorine-resistant and hydrofluoric acid-resistant materials; It has excellent mechanical properties and is widely used from low temperature to high temperature. It has been widely used in the fields of chemistry, petrochemical industry and marine development. It can be used in various heat exchange equipment, boiler feed water heaters, petroleum and chemical pipelines, sulfuric acid, hydrogen fluoride, etc. acid alkylation unit. In terms of welding, Monel 400 alloy has high thermal crack sensitivity, and it is difficult to control its welding process. During the ...

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Problems solved by technology

In terms of welding, Monel 400 alloy has high thermal crack sensitivity, and it is difficult to control its welding process

During the welding process, the welding zone is very easy to form a highly directional columnar crystal structure, so that impurities such as phosphorus and sulfur segregate in the center of the weld, and form a low melting point eutectic with nickel, increasing the tendency of hot cracking in the weld zone. Weaken the mechanical properties of the weld; if there are pollutants on the surface of the weldment, slag inclusions or small discontinuous oxides are easy to form at the weld, and it is difficult to detect by general flaw detection methods; due to the poor fluidity of Monel 400 alloy, solidification shrinkage If the welding quantity is large, it is easy to generate large welding stress during welding, resulting in crystalline cracks in the weld; once the welding current input is too large, it will not only cause overheating of the molten pool, increase the tendency of hot cracking, but also evaporate the weld metal deoxidizer, porosity

At present, welding is the key technology for manufacturing the impeller of corrosion-resistant alloy pump of Monel 400 with narrow channel. The existing manual welding process has low work efficiency and low pass rate of non-destructive testing.

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