Flux-Cored Nickel Alloy Wire for 9% Ni Steel Welding
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Solution Overview
Problem
Existing flux-cored nickel-based alloy wires used in gas-shielded arc welding suffer from welding defects such as pits, degraded arc stability, and poor resistance to hot cracking, especially in horizontal fillet and vertical upward welding positions, due to imbalances in slag-forming materials and oxide content.
Innovation Solution
A flux-cored nickel-based alloy wire with a sheath containing 50% nickel and a flux with specific ranges of TiO2, SiO2, ZrO2, manganese oxides, and alkali metal compounds, optimized to achieve excellent weldability, pitting resistance, and hot cracking resistance across various welding positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flux contains high TiO2 and ZrO2 content to improve resistance to hot cracking, then resistance to hot cracking is improved, but welding defects such as pits occur on bead surfaces
Solution Approach 1:
The patent precisely controls the parameters of slag-forming materials by limiting TiO2 to 3-11%, ZrO2 to 1-3%, and SiO2 to 0.2-1.3%, with a specific ratio (TiO2+ZrO2)/SiO2 of 7.0-14.5. This parameter optimization prevents excessive slag formation that causes pits while maintaining sufficient resistance to hot cracking through balanced oxide composition.
2Reliability
If iron oxides and manganese oxides are added to improve resistance to hot cracking, then resistance to hot cracking is improved, but Si content in weld metal cannot be controlled and pitting occurs
Solution Approach 1:
The patent adds MnO2 within 0.3-1.0% to promote Si oxidation and removal, while simultaneously controlling SiO2 in flux at 0.2-1.3% to regulate Si content in weld metal. This dual control mechanism achieves both Si content precision (0.03-0.15%) and resistance to hot cracking through balanced oxide interactions.
Solution Approach 2:
The patent converts the potential harm of Si accumulation (which causes pits) into a benefit by using MnO2 to oxidize Si and form SiO2 slag, which is then removed. This transforms Si from a harmful impurity into a controlled component that improves weld quality when properly managed through flux composition.
3Reliability
If slag-forming materials are increased to improve weldability and resistance to hot cracking, then resistance to hot cracking is improved, but arc stability degrades
Solution Approach 1:
The patent optimizes the total oxide content and specific ratios to balance slag formation with arc stability. By controlling (TiO2+ZrO2)/SiO2 within 7.0-14.5 and limiting total slag-forming materials, the flux produces adequate slag for hot cracking resistance while maintaining arc stability through balanced chemical composition and controlled reactivity.
4Object-affected harmful factors
If the flux composition is optimized for horizontal fillet welding to prevent pits, then pitting resistance is improved, but weldability in vertical upward welding deteriorates
Solution Approach 1:
The patent creates a universal flux composition that performs multiple functions simultaneously: TiO2 and ZrO2 provide hot cracking resistance and form protective slag, MnO2 controls Si content and promotes slag formation, while Na2O and K2O regulate slag fluidity. This multi-functional composition achieves consistent weldability across all positions by balancing slag characteristics that work for both horizontal and vertical welding.
Solution Approach 2:
The patent adjusts slag-forming material parameters to create optimal slag fluidity and solidification characteristics. By controlling the ratio (TiO2+ZrO2)/SiO2 at 7.0-14.5 and adding Na2O (0.1-0.5%) and K2O (0.1-0.5%), the slag maintains appropriate viscosity for horizontal welding while solidifying at a rate that prevents defects in vertical upward welding, achieving position-independent 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 provides superior weldability, pitting resistance, and hot cracking resistance, with improved arc stability and bead appearance, by controlling the composition of the sheath and flux to meet specific AWS standards, enhancing the performance in all welding positions.
Implementation Method 1
gas-shielded arc welding
Implementation Method 2
a flux having specific contents of TiO2, SiO2 and ZrO2 as slag-forming materials
Data Source
Figure 1A~3
AI summary
A flux-cored nickel-based alloy wire contains, based on the total mass of the wire, 3 to 11 percent by mass of TiO2, 0.2 to 1.3 percent by mass of SiO2, 1 to 3 percent by mass of ZrO2, and 0.3 to 1. 0 percent by mass of manganese oxides in terms of MnO2, contains of a total of 0.2 to 1.0 percent by mass in terms of Na, K and Li of sodium compounds, potassium compounds, and lithium compounds. The flux has a ratio ( ( [TiO2] + [ZrO2] ) / [SiO2] ) of the total of the TiO2 and ZrO2 contents to the SiO2 content of 5. 0 to 14.5, in which [TiO2] , [SiO2] and [ZrO2] represent TiO2, SiO2 and ZrO2 contents. The wire shows excellent weldability in welding of all positions typically on 9% nickel steels and nickel-based alloy steels and gives a weld metal having good pitting resistance, bead appearance, and resistance to hot cracking.