Flux-cored wire for electrogas welding and electrogas welding metal

Abstract

A flux-cored wire for electro gas arc welding is provided to improve strength, elongation and toughness of the weld metal and obtain excellent welding workability with respect to steel plates with a wide width and a thickness of 25 to 70 mm, and an electro gas arc weld metal manufactured using the flux-cored wire for electro gas arc welding is provided. As a flux-cored wire for electro gas arc welding formed by filling a flux in a steel sheath, the flux-cored wire for electro gas arc welding contains, per the total mass of the wire, 0.03 to 0.07 mass% of C, 0.3 to 0.8 mass% of Si, 1.5 to 2.2 mass% of Mn, 0.4 to 1.5 mass% of Ni, 0.05 to 0.60 mass% of a total of Cr and Mo, 0.02 to 0.20 mass% of Ti, 0.005 to 0.020 mass% of B, 0.20 to 0.50 mass% of Mg, controls Al to not more than 0.10 mass%, and contains 1.0 to 2.0 mass% of a slag forming agent, the slag forming agent containing, per the total wire mass, 0.30 to 0.70 mass% of F and 0.02 to 0.20 mass% of K, wherein [A] is 0.10 to 1.0 and [B] is 0.12 to 0.58 when [A] and [B] are values determined by equations [A]=(Cr+Mo) / Ni and [B]=C / (Ti+20xB) from contents of Cr, Mo, Ni, C, Ti, and B respectively.

Description

technical field [0001] The present invention relates to a single-electrode gas-electric welding flux-cored wire and a gas-electric welding metal capable of performing vertical one-layer bead welding with a plate thickness of 25 mm to 70 mm. Background technique [0002] As a high-efficiency vertical welding method, electrogas arc welding is used in a wide range of fields such as ships, oil storage tanks and bridges. In recent years, with the rapid economic and industrial development of China and East Asian countries, the increase in the size of container ships has been rapidly promoted for the purpose of efficient transportation of containerized cargo due to the increase in logistics volume. [0003] Along with the increase in size of container ships, thickening of ship side shells, hatch coamings, and the like is advancing, and steel plates having a plate thickness of 50 mm or more are used. As a construction method capable of efficiently welding such thick steel plates, t...

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Problems solved by technology

[0006] However, if a large amount of alloying elements such as Mn, Ni, and Mo are added from the welding wire in this way, the dilution of the base metal is likely to change due to the voltage deflection during welding construction, etc., so the chemical composition of the weld metal fluctuates drastically, and it has been confirmed that it is not possible to meet the requirements. The condition of the specified performance

[0007] In particular, from the standpoint of construction efficiency, the demand from users is to develop welding wires that can be applied to a wide range of plate thicknesses from thin plates to thick plates. Welding wires for thick steel materials, because alloy components are added to ensure strength, Therefore, in the relative thin plate, the tensile strength becomes too high, and it is difficult to obtain the elongation in the tensile test, and it is confirmed that the elongation of 22% relative to the ship class standard applied in the shipbuilding field is insufficient.

In addition, toughness also tends to deteriorate

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