Flux-Cored Wire Composition for Low-Temperature Welding
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Solution Overview
Problem
Current welding technologies for Ni-based steel at very low temperatures face challenges in achieving low temperature toughness, high welding efficiency, and reducing nickel content while minimizing oxygen levels and cold cracking, often requiring expensive materials and preheating.
Innovation Solution
A flux-cored wire with a reduced nickel content (5.5% to 9.5%) and a specific slag composition including metal fluorides and oxides, used in gas-shielded arc welding with pure Ar or low O2/CO2 shielding gas, to stabilize arcs and reduce oxygen in the weld metal, eliminating the need for preheating and enhancing toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ni-based alloy welding material with 60% to 80% Ni is used, then low temperature toughness is improved, but welding material cost increases and welding efficiency deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the welding wire by reducing Ni content from 60-80% to 5.5-9.5%, matching the base metal composition. This parameter change enables the use of gas-shielded arc welding instead of TIG welding, significantly improving welding efficiency while maintaining low temperature toughness through optimized alloying elements (Mn: 1.5-3.0%, Si: 0.5-2.0%, Cr: 0.5-2.0%) and controlled impurity levels
Solution Approach 2:
The patent replaces expensive Ni-based alloy welding material with a cheaper wire composition that uses less Ni (5.5-9.5%) and more economical alloying elements. This substitution achieves comparable low temperature toughness at reduced material cost, making the welding process more economically viable while improving productivity
2Quantity of substance
If Ni content is reduced to 5.5% to 9.5%, then welding material cost is reduced, but cold cracking resistance deteriorates
Solution Approach 1:
The patent changes multiple compositional parameters simultaneously: reduces Ni to 5.5-9.5%, optimizes Mn to 1.5-3.0%, Si to 0.5-2.0%, Cr to 0.5-2.0%, and严格控制 impurities (P≤0.03%, S≤0.03%, O≤0.008%). This coordinated parameter change achieves cost reduction while preventing cold cracking through balanced alloy design that controls martensite formation and hydrogen content
Solution Approach 2:
The patent creates a composite welding wire composition that combines multiple alloying elements (Ni, Mn, Si, Cr) in specific proportions rather than relying on high Ni content alone. This composite approach provides synergistic effects that maintain cold cracking resistance through controlled microstructure formation while reducing overall Ni content and material cost
3Productivity
If high heat input is used, then welding efficiency is improved, but weld defects such as incomplete fusion increase
Solution Approach 1:
The patent changes the compositional parameters of the welding wire to enable stable arc characteristics and proper slag formation. The optimized composition (Ni: 5.5-9.5%, Mn: 1.5-3.0%, Si: 0.5-2.0%) facilitates gas-shielded arc welding process that achieves complete fusion at moderate heat inputs, eliminating the need to choose between high heat input with defects or low heat input with reduced efficiency
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 solution achieves cost-effective welding with improved low temperature toughness, high welding efficiency, and reduced cold cracking resistance without preheating, using a flux-cored wire with a tailored composition and shielding gas, effectively addressing the limitations of existing methods.
Implementation Method 1
gas-shielded arc welding
Implementation Method 2
gas-shielded arc welding with pure Ar or low O2/CO2 shielding gas
Data Source
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AI summary
[Object] There is provided a flux-cored wire capable of obtaining a weld metal having excellent low temperature toughness and improving welding efficiency, in which preheating performed for preventing cold cracking can be omitted or simplified. [Means for Solving Problems] The flux-cored wire includes one or more of CaF2, BaF2, SrF2, MgF2, and LiF and, when a total amount thereof is defined as α, the α is 2.0% to 7.0%, by mass%, with respect to a total mass of the flux-cored wire, one or more of a Ti oxide, a Si oxide, a Mg oxide, an A1 oxide, a Zr oxide, and a Ca oxide are included in the flux-cored wire, and when a total amount thereof is defined as β, the β is 0.2% to 0.9%, by mass%, with respect to the total mass of the flux-cored wire, a ratio of an amount of the CaF2 with respect to the α is 0.90 or more, and a ratio of the α with respect to the β is 3.0 or more and 15.0 or less.