Flux-Cored Wire Composition for Welding Toughness and Cracking
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Solution Overview
Problem
Conventional flux-cored wires for all-position welding face challenges in achieving high strength, toughness, and resistance to hot and cold cracking, while also ensuring low-temperature toughness and welding workability, especially in offshore structures and line pipes.
Innovation Solution
A flux-cored wire with a steel outer sheath filled with a flux containing specific elements like C, Mn, TiO2, Ni, Si, and F, with controlled particle size ratios to enhance weld metal strength, toughness, and cracking resistance, and optimized composition to improve welding workability and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional flux-cored wire composition is used for all-position welding, then welding efficiency is improved, but low-temperature toughness deteriorates due to high oxygen content in weld metal
Solution Approach 1:
The patent changes the chemical composition parameters of the flux, specifically controlling Al content to 0.05% or less and adjusting the balance between CaO (20-40%), MgO (10-30%), and other oxides to achieve low oxygen content in weld metal while maintaining good welding performance and low-temperature toughness
Solution Approach 2:
The patent creates a composite flux system combining multiple oxide components (CaO, MgO, SiO2, Al2O3, TiO2, B2O3) in specific proportions to achieve synergistic effects that reduce oxygen content while improving both welding efficiency and low-temperature toughness properties
2Strength
If flux composition is optimized for low oxygen content, then low-temperature toughness is improved, but hot cracking resistance deteriorates
Solution Approach 1:
The patent carefully adjusts the flux composition parameters, particularly controlling CaO content (20-40%) and MgO content (10-30%) while adding B2O3 (1-5%) and TiO2 (5-15%) to achieve a balance that provides both low-temperature toughness and hot cracking resistance through optimized slag formation and cooling characteristics
Solution Approach 2:
The patent develops a composite flux system where multiple oxide components work synergistically: CaO and MgO provide basicity for toughness, while B2O3 and TiO2 contribute to crack resistance through controlled slag viscosity and cooling rate, achieving both low-temperature toughness and hot cracking resistance simultaneously
3Reliability
If flux composition is adjusted for hot cracking resistance, then reliability is improved, but welding workability deteriorates
Solution Approach 1:
The patent optimizes flux composition parameters including CaO (20-40%), SiO2 (10-30%), and Al2O3 (5-20%) to achieve appropriate slag fluidity and cooling characteristics that provide hot cracking resistance while maintaining good welding workability through balanced slag formation and bead shape control
4Strength
If multiple alloying elements are added to improve mechanical properties, then strength is improved, but complexity of composition increases
Solution Approach 1:
The patent optimizes the content ranges of multiple alloying elements (Mn: 2.0-5.0%, Si: 0.5-2.0%, Cr: 0.5-2.0%, Mo: 0.1-1.0%, Ni: 0.1-1.0%, Ti: 0.1-0.5%, B: 0.005-0.050%) to achieve the desired mechanical properties while controlling composition complexity through defined concentration ranges that ensure consistent performance
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 wire achieves excellent welding workability, cold cracking resistance, low-temperature toughness, mechanical properties, and defect resistance, while also providing enhanced hot cracking resistance and improved bead shape and fluidity.
Implementation Method 1
gas-shielded arc welding
Implementation Method 2
forms a low-oxygen and low-hydrogen weld metal
Data Source
Figure 1(a)~1(e)
AI summary
Provided is a flux-cored wire for gas-shielded arc welding that contains, per wire total mass, specific amounts of C, Mn, TiO2 and specific amounts or less of P and S, and contains, in the flux, a specific amount of Ni per wire total mass. The Ni has a ratio (α1/α2) of 0.50-1.00 when α1 (mass%) is the content per wire total mass of particles having a size of 106 µm or less and α2 (mass%) is the content per wire total mass of particles having a size exceeding 106 µm.