Flux-Cored Wire Composition for Bi-Free Slag Removability
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Solution Overview
Problem
Existing flux-cored wires for welding stainless steel suffer from poor welding usability, particularly in terms of slag removability, especially for fixed pipe joints, due to the absence of Bi and inadequate component composition.
Innovation Solution
A flux-cored wire composition is developed with specific metallic components, including Cr, Ni, Mn, Si, Zr, TiO2, SiO2, and ZrO2, with controlled Bi content below 0.0020 mass%, and a parameter A=[Si]+2×[Zr] ranging from 1.4 to 2.5, to enhance welding usability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Bi is added to improve slag removability, then welding usability is improved, but hot-cracking resistance and corrosion resistance deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters by strictly limiting Bi content to less than 0.0020 mass% (effectively eliminating Bi) while optimizing other elements like increasing Zr to 0.2-0.8 mass% and adjusting Si to 0.1-1.1 mass%, maintaining the parameter relationship A=[Si]+2×[Zr] between 1.4-2.5. This parameter substitution resolves the contradiction by achieving slag removability without Bi while preserving hot-cracking resistance.
Solution Approach 2:
The patent introduces Zr as an intermediary element to replace Bi's function in slag removability. By adding Zr (0.2-0.8 mass%) and controlling its interaction with Si and flux components, the patent achieves effective slag removal through Zr-containing inclusions rather than Bi, thereby maintaining welding usability without the harmful effects of Bi on hot-cracking resistance.
2Ease of operation
If Bi is added to improve slag removability, then welding usability is improved, but corrosion resistance deteriorates
Solution Approach 1:
The patent changes the compositional parameters by eliminating Bi (content < 0.0020 mass%) and adjusting protective element contents, particularly Cr (16.0-22.0 mass%) and Ni (6.0-11.0 mass%), to maintain high corrosion resistance. This parameter optimization achieves welding usability improvement without compromising corrosion resistance.
Solution Approach 2:
The patent uses Zr as an intermediary to achieve slag removability functions previously attributed to Bi, while Cr and Ni serve as intermediaries to maintain corrosion resistance. The coordinated adjustment of these elements resolves the contradiction between improving welding usability and maintaining corrosion resistance.
3Ease of operation
If Bi is added to improve slag removability, then welding usability is improved, but low-temperature toughness deteriorates
Solution Approach 1:
The patent optimizes compositional parameters by eliminating Bi and adjusting Ni (6.0-11.0 mass%) and Cr (16.0-22.0 mass%) contents to maintain low-temperature toughness. The controlled composition with Zr (0.2-0.8 mass%) and Si (0.1-1.1 mass%) achieving A=[Si]+2×[Zr]=1.4-2.5 provides both slag removability and preserved low-temperature toughness.
4Ease of operation
If flux composition is optimized for slag removability, then welding usability is improved, but mechanical properties deteriorate
Solution Approach 1:
The patent optimizes flux composition parameters including TiO2 (5.0-9.0 mass%), SiO2 (0.1-2.0 mass%), and ZrO2 (0.5-3.0 mass%) to improve slag removability while maintaining mechanical properties. The coordinated adjustment of flux components with wire composition (Cr, Ni, Mn, Si, Zr) achieves both improved welding usability and preserved mechanical strength through balanced parameter optimization.
Data Source
AI summary
A flux-cored wire for arc welding, including a steel sheath filled with flux, where the wire contains, relative to a total mass of the wire, Cr: 16.0 to 22.0 mass %, Ni: 6.0 to 11.0 mass %, Mn: 0.7 to 2.6 mass %, Si: 0.1 to 1.1 mass %, Zr: 0.2 to 0.8 mass %, Fe: 45.0 to 65.0 mass %, TiO2: 5.0 to 9.0 mass %, SiO2: 0.1 to 2.0 mass %, ZrO2: 0.5 to 3.0 mass %, and Bi: less than 0.0020 mass %. Where by mass %, a Si content is denoted by [Si] and a Zr content is denoted by [Zr], a value of parameter A expressed by A=[Si]+2×[Zr] satisfies 1.4 to 2.5.