Flux Cored Wire Hygroscopicity Control via Mg Distribution
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Solution Overview
Problem
Conventional flux cored wires for gas shielded arc welding suffer from high hygroscopicity, leading to increased hydrogen content in weld metals and subsequent cold cracks, while existing solutions fail to adequately address the hygroscopic properties of the flux.
Innovation Solution
A flux cored wire with a specific acid-soluble Mg content distribution within the flux, where the Mg content is categorized by particle size and mass percentage, improving resistance to hygroscopicity and welding workability, and including additional components like Ti, Si, Mn, and Fe to enhance mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flux is used in flux cored wire, then welding workability is achieved, but the flux absorbs moisture from air during storage, leading to increased hydrogen content in weld metal and cold cracks
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution of flux components and the content of acid-soluble Mg in different particle size ranges. By setting specific Mg content ranges (0.1-5% for ≤75μm, 0.1-7% for 75-106μm, and 1-15% for >106μm), the flux achieves reduced hygroscopicity while maintaining welding performance, thereby reducing hydrogen content in weld metal without sacrificing reliability
Solution Approach 2:
The patent uses composite materials by creating a flux composition with multiple components having different particle sizes and Mg contents. The flux is composed of three particle size fractions, each with controlled Mg content, forming a composite structure that reduces moisture absorption while maintaining welding workability and producing low-hydrogen weld metal
2Ease of operation
If acid-soluble Mg content is increased to improve welding workability, then arc stability improves, but hygroscopicity of the flux increases
Solution Approach 1:
The patent applies local quality by distributing acid-soluble Mg non-uniformly across different particle size fractions of the flux. Smaller particles (≤75μm) have lower Mg content (0.1-5%), medium particles (75-106μm) have moderate Mg content (0.1-7%), and larger particles (>106μm) have higher Mg content (1-15%). This localized variation in Mg content optimizes arc stability while controlling overall hygroscopicity
Solution Approach 2:
The patent segments the flux into three distinct particle size categories, each with independently controlled Mg content. This segmentation allows different regions of the flux to serve different functions: smaller particles contribute to arc stability with lower Mg, while larger particles provide additional welding performance with higher Mg, but contribute less to hygroscopicity due to their smaller surface area-to-volume ratio
Data Source
Figure 1(a)~1(e)
AI summary
Provided is a flux cored wire for gas shielded arc welding that has excellent resistance to hygroscopicity and adequate welding workability and can produce weld metal with excellent mechanical properties. The flux cored wire for gas shielded arc welding is formed by filling a flux into a steel outer sheath, in which the flux contains acid-soluble Mg, a content of the acid-soluble Mg in a first flux component having a particle diameter of 75 µm or less in the flux is set at 0.1 to 5% by mass relative to the total mass of the first flux component, a content of the acid-soluble Mg in a second flux component having a particle diameter of more than 75 µm and 106 µm or less in the flux is set at 0.1 to 7% by mass relative to the total mass of the second flux component, and a content of the acid-soluble Mg in a third flux component having a particle diameter of more than 106 µm in the flux is set at 1 to 15% by mass relative to the total mass of the third flux component.