Filling flux welding wire

Abstract

To provide a flux-filled welding wire that is excellent in high temperature crack resistance that poses a problem in the first-layer welded portion of a one-sided butt joint welding of steel plates made of mild steel or high-tensile steel, and has excellent welding operability and weld metal in all posture welding Mechanical properties are excellent. It is a flux-filled welding wire that is used for welding steel plates made of mild steel or high-tensile steel, and has a steel sheath filled with flux. It is characterized in that the flux filling rate relative to the total mass of the welding wire is The specified amount contains C, Si, Mn, Ti, TiO2, Al, Al2O3, B, N, Ni (including 0 mass%), Cu (containing 0 mass%) in a specified amount relative to the total mass of the welding wire, and satisfies 10≥( Ni+14×C+0.29×Mn+0.30×Cu) / (1.5×Si)≧2.5 (the element symbol in the formula indicates the content (mass %) of the element).

Description

technical field [0001] The present invention relates to a filled flux welding wire (Japanese: フラックス入ヮィャ) used for gas-shielded arc welding of steel plates made of mild steel and high-tensile steel, and more particularly to a titanium dioxide-based filled flux welding wire. Background technique [0002] Filled flux wire used for welding steel plates made of mild steel and high-tensile steel has a better weld bead appearance, better welding workability, and better deposition efficiency than solid wire, so its usage is increasing year by year. However, since the welding speed of the filled flux welding wire is higher than that of the solid core welding, high-temperature cracks tend to easily occur especially in the first-layer welded part of the single-sided butt joint welding. As a method of suppressing the occurrence of such high-temperature cracks, the following techniques have been proposed. [0003] For example, in Patent Document 1, as a method for improving resistance t...

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Problems solved by technology

[0004] However, the problem in the improvement method of Patent Document 1 is that the application of welding construction conditions to improve welding efficiency is expanding recently, and there is also a limit to the reduction of the S content of the impurity element that is a welding wire component, so that it cannot be suppressed. High Temperature Cracks Occurring on Weld Metals

There is also a problem that the reduction of the B content of the wire component proposed in Patent Document 1 is effective in improving the high-temperature crack resistance, but causes a decrease in low-temperature toughness.

However, as a method of improving the high-temperature crack resistance of mild steel, which is the object of the present invention, no specific method is shown regarding the method of controlling the solidification mode, and no guidelines such as composition design guidelines are shown.

[0013] In addition, even if the solidification mode prediction formula proposed for stainless steel alloys is applied to mild steel, there is still a problem that the solidification mode prediction formula is originally constructed for stainless steel alloys, and the prediction accuracy of the solidification mode when applied to mild steel, etc. is low.

[0014] In addition, as shown in Patent Document 2, in "controlling the crystallization timing of austenite or delta ferrite crystallized after the initial phase crystallization, making it early, cutting off the liquid phase remaining in the form of a film, thereby generating fracture cracks The direction of propagation of the weld solidification cracks can be suppressed from increasing.” In the research method of this method, the improvement of the high temperature crack resistance of mild steel, etc., which is the object of the present invention, is not enough.

This is due to the following point: the solidification mode in the composition range of mild steel etc. is already "FA mode", and even if the above research is applied, the high temperature crack resistance cannot be further improved

Therefore, in the improvement method of Patent Document 2, the current situation is that there is a demand for further improvement of the efficiency of welding work recently, and sufficient high temperature crack resistance cannot be obtained.

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