Flux-Cored Wire for Low-Temperature Steel Welding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current welding technologies for Ni-based steel at very low temperatures face challenges in achieving low temperature toughness, reducing welding material costs, and improving welding efficiency while minimizing cold cracking and oxygen content in weld metals.
Innovation Solution
A flux-cored wire with a reduced Ni 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 a mixed gas with less than 2% O2, to stabilize arcs and reduce oxygen levels in the weld metal.
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 significantly
Solution Approach 1:
The patent changes the Ni content parameter from 60-80% in conventional welding materials to 5.5-9.5% in the flux-cored wire, achieving cost reduction while maintaining low temperature toughness through optimized composition ratios of Ni, C, Si, Mn, and other alloying elements
Solution Approach 2:
The patent creates a composite welding material structure with an outer steel sheath containing 6-16% Ni and a flux core containing specific amounts of Ni powder (3-15%), C, Si, Mn, and other elements, where the combination of sheath and core materials achieves the desired mechanical properties at reduced cost
2Quantity of substance
If Ni content in welding material is reduced to 5.5% to 9.5%, then welding material cost is reduced, but cold cracking resistance deteriorates
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: Ni content (5.5-9.5% in wire, 3-15% in flux), C content (0.05-0.25% in wire, 0.03-0.15% in flux), Si content (0.1-0.5% in wire, 0.05-0.3% in flux), and Mn content (0.5-2.0% in wire, 0.3-1.0% in flux) to achieve the appropriate Ceq range (0.25-0.50%) that prevents cold cracking
Solution Approach 2:
The patent performs preheating before welding to prevent cold cracking, applying preliminary thermal action to the workpiece to ensure the weld metal does not crack during cooling, complementing the optimized composition design
3Quantity of substance
If gas-shielded arc welding with pure Ar or low O2 mixed gas is used, then oxygen content in weld metal is reduced, but arc stability deteriorates
Solution Approach 1:
The patent introduces an arc stabilizer substance (such as potassium fluoride or sodium fluoride) as an intermediary component in the flux composition that mediates between the low-oxygen shielding gas environment and the arc, providing sufficient ionization and stability without introducing excessive oxygen into the weld metal
Solution Approach 2:
The patent adjusts the oxygen content parameter in the shielding gas to 1.0% or less (conventional gases have 2-5% O2) and compensates by optimizing the flux composition with specific deoxidizing elements and arc stabilizers to maintain arc stability at lower oxygen levels
4Reliability
If preheating is performed to prevent cold cracking, then cold cracking resistance is improved, but welding efficiency decreases
Solution Approach 1:
The patent applies partial preheating action by optimizing the composition to achieve appropriate Ceq (0.25-0.50%) that reduces cold cracking susceptibility, allowing reduced or eliminated preheating compared to conventional low-Ni welding materials, thereby improving welding efficiency while maintaining sufficient cold cracking resistance
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 enables the production of weld metals with excellent low temperature toughness and reduced oxygen content, enhancing welding efficiency and eliminating the need for preheating to prevent cold cracking, thereby reducing costs and improving the quality of welds.
Implementation Method 1
A flux-cored wire with a reduced Ni 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 a mixed gas with less than 2% O2, to stabilize arcs
Implementation Method 2
used in gas-shielded arc welding with pure Ar or a mixed gas with less than 2% O2, to stabilize arcs and reduce oxygen levels in the weld metal
Implementation Method 3
flux-cored wire for gas-shielded arc welding of Ni steel for very low temperature use containing 5.5% to 9.5% of Ni
Data Source
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 Al 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.