Flux-Cored Wire Composition for Stable Vertical and Overhead Welding

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Solution Overview

Problem

Existing flux-cored wires face challenges in achieving suitable welding performance and efficiency, particularly in vertical and overhead positions, due to limitations in welding current and speed, leading to issues like burn-through and bead shape defects.

Innovation Solution

A flux-cored wire composition including specific fluoride powders and strong deoxidizing metal elements, optimized to maintain a stable arc and form a uniform oxide film, allowing for higher deposition rates and improved bead shape in all welding positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If welding current and welding speed are increased to improve productivity, then welding efficiency improves, but bead shape defects such as burn-through, overlap, and undercut occur in vertical and overhead positions

Engineering Contradiction:
Improvewelding efficiencyVSAvoidbead shape quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The invention changes the chemical composition parameters of the flux-cored wire by optimizing the content ranges of Ca (0.01-2.00%), Mg (0.01-2.00%), Al (0.01-2.00%), and Ti (0.01-1.00%). These compositional changes modify the flux properties to control molten pool behavior, allowing higher welding currents and speeds without causing bead shape defects in vertical and overhead positions.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The flux-cored wire uses a composite flux composition combining multiple deoxidizing elements (Ca, Mg, Al, Ti) with specific oxide components. This composite material approach creates synergistic effects that improve arc stability and molten pool control, enabling high-productivity welding in challenging positions while maintaining bead quality.

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If welding current is reduced to prevent burn-through in overhead welding, then bead shape quality improves, but welding speed must be reduced leading to lower productivity

Engineering Contradiction:
Improvebead shape qualityVSAvoidwelding efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

By modifying the flux composition parameters, particularly the deoxidizing element contents, the invention changes the physical and chemical properties of the molten pool. This allows welding processes to operate at higher currents and speeds that would otherwise cause defects, thus improving productivity without sacrificing bead quality in overhead positions.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If flux composition is optimized to improve arc stability and deposition rate, then welding efficiency improves, but control over molten pool in gravitational positions becomes more difficult

Engineering Contradiction:
Improvedeposition rateVSAvoidmolten pool control
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The flux uses a composite composition with specific combinations of Ca, Mg, Al, and Ti along with their oxides. This composite material provides balanced deoxidation, arc stabilization, and molten pool fluidity control, enabling high deposition rates while maintaining adequate control over the molten pool in vertical and overhead gravitational positions.

Inventive Principle:
Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The flux-cored wire enhances welding efficiency by preventing burn-through and forming suitable beads, even in challenging positions, through controlled heat energy application and optimized flux composition.

Implementation Method 1

gas-shielded arc welding

Methodology Applied
Scientific EffectElectric arc: Electric Arc

Implementation Method 2

a suitable oxide film can be formed on the surface of a molten pool

Methodology Applied
Scientific EffectOxidation: Oxidation

Implementation Method 3

includes a specific fluoride powder and a specific strong deoxidizing metal element

Methodology Applied
Scientific EffectReduction: Reduction

Data Source

PatentEP3967444B1Flux-cored wire and welding method
Publication Date: 2025.09.17 KOBE STEEL LTD
  • EP3967444B1 patent drawingFigure 1
  • EP3967444B1 patent drawingFigure 2
  • EP3967444B1 patent drawingFigure 3

AI summary

The present invention relates to a flux-cored wire for positive polarity gas-shielded arc welding use, in which a flux contains a metal powder and also contains BaF2 and SrF2 and AlF3 and/or CaF2 as fluorides wherein the content of BaF2 is 1.0 to 4.5%, the content of SrF2 is 2.0% or less, the content of CaF2 is 0.45% or less and the content of AlF3 is 0.70% or less, at least one of metal elements constituting the flux and the fluorides is a strong deoxidizing metal element having a specified standard formation Gibbs energy, and the content of each of an oxide and a carbonate in the flux is 0.5% or less.