Flux for Submerged Arc Welding

Abstract

Provided is a flux for submerged arc welding that has good welding operability regardless of whether the welding power source is AC or DC, and can reduce the amount of diffusible hydrogen in the weld metal. The flux for submerged arc welding is made into the following composition: MgO: 25 to 35 mass%, F (CaF2 converted value): 15 to 30 mass%, Al2O3: 10 to 25 mass%, SiO2: 10 to 20 mass%, Na ( At least one of Na2O converted value) and K (K2O converted value): total 0.5 to 5.5 mass%, Fe (FeO converted value): 0.5 to 5 mass%, TiO2: 1 to 5 mass%, CaO: 6 mass% The following, Mn (MnO converted value): less than 2.0 mass%, and water-soluble SiO2: 1 mass% or less, satisfy the following mathematical expression (I).

Description

technical field [0001] The present invention relates to fluxes for submerged arc welding. More specifically, it relates to high-temperature firing type flux. Background technique [0002] Fluxes used in submerged arc welding are roughly classified into melting type fluxes and firing type fluxes according to their shape. Melting flux is manufactured by melting and pulverizing various raw materials in an electric furnace or the like. On the other hand, firing-type fluxes are manufactured by binding various raw materials with a binder such as alkali silicate, granulating them, and firing them. [0003] In addition, firing-type fluxes are classified according to the firing temperature. Generally speaking, those fired at 400-600°C are called low-temperature firing-type fluxes, and those fired at 600-1200°C are called high-temperature firing-type fluxes. Furthermore, various studies have been made conventionally in order to reduce the diffusion of hydrogen into the weld metal i...

AI Technical Summary

Problems solved by technology

In addition, in the technology described in Patent Document 4, although the specific surface area can be reduced, the specific surface area of ​​the flux has a great influence on the barrier property of the slag during welding.

Specifically, if the specific surface area of ​​the flux is reduced, the slag barrier property is impaired, the nitrogen content in the weld metal increases, and the toughness of the weld metal deteriorates.

[0014] On the other hand, the technology described in Patent Document 5 regarding high-temperature sintered flux is designed for the main purpose of corresponding to AC welding power sources. Degradation of operability is not considered

That is, with the flux described in Patent Document 5, if the welding power source is a direct-current type, the same effect as when an alternating-current type is used cannot be obtained.

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