Filling flux welding wire

Abstract

To provide a flux-filled welding wire that is excellent in high temperature crack resistance at the root weld of single-sided butt joint welding of steel plates made of mild steel or high-tensile steel, and has excellent welding workability and weld metal in all-posture welding superior mechanical properties. A flux-filled welding wire which is used in welding of steel plates composed of mild steel or high-strength steel and is formed by filling a steel sheath with flux, characterized in that the flux filling ratio relative to the total mass of the welding wire It is a specified amount, relative to the total mass of the welding wire, containing a specified amount of C, Si, Mn, Ti, TiO2, Al, Al2O3, B, N, Ni (including 0 mass%), Cu (including 0 mass%), and satisfying 10≧(Ni+14×C+0.29×Mn+0.30×Cu) / (1.5×Si)≧2.8, where the symbol of an element in the formula indicates the content (mass %) of the element.

Description

technical field [0001] The present invention relates to a filled flux welding wire used for gas-shielded arc welding of steel plates made of mild steel or high-tensile steel, and more particularly to a titanium dioxide-based filled flux welding wire. Background technique [0002] Filled flux wires used for welding steel plates made of mild steel and high-tensile steel are increasing year by year due to their better weld bead appearance, better welding workability and superior deposition efficiency than solid wires. However, since the welding speed of the filled-flux welding wire is higher than that of the solid welding wire, high-temperature cracks tend to be easily generated especially at the root welding portion of the single-face butt joint welding. As a method of suppressing the occurrence of such high-temperature cracks, the following techniques are proposed. [0003] For example, Patent Document 1 proposes a method for improving high-temperature crack resistance by pe...

AI Technical Summary

Problems solved by technology

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 for the method of controlling the solidification mode, and the direction of composition design is not given.

[0017] In addition, even if the solidification mode prediction formula proposed for stainless alloys is applied to mild steel, the solidification mode prediction formula is originally constructed for stainless alloys, so there is a solidification mode when it is applied to mild steel, etc. The problem of low prediction accuracy

[0018] Furthermore, as shown in Patent Document 3, in "controlling to advance the crystallization time of austenite or delta ferrite crystallized after the primary phase crystallization, fracture cracks are generated by dividing the liquid phase remaining in the form of a film." In this idea, how to improve the high temperature crack resistance of mild steel, which is the object of the present invention, is not enough.

This is because the solidification mode of mild steel and the like in the composition range is already "FA mode", and even if the above considerations are applied, the high temperature crack resistance cannot be further improved

Therefore, in the improvement method of Patent Document 3, it is currently impossible to obtain sufficient high-temperature cracking resistance for the recent further improvement of welding work efficiency.

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