High-Cr GMAW Wire Composition for Stable Arc Welding
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Solution Overview
Problem
High-temperature and high-pressure environments in power boilers require welding materials with excellent mechanical performance and automation capabilities, but existing techniques face challenges with Cr oxide formation leading to welding defects like lack of fusion and bad bead shapes during gas metal arc welding (GMAW) of high-Cr steel, making automation difficult.
Innovation Solution
A gas shielded arc welding wire with specific composition (C: 0.01-0.50%, Si: 0.01-1.50%, Mn: 0.10-2.50%, Cr: 5-15%, Ni: 0.05-1.50%, Mo: 0.1-2.0%, V: 0.1-1.0%, Nb: 0.01-0.20%, REM: 0.001-0.050%, S: 0.001-0.020%, O: ≤0.025%) and a welding method using inert gases like Ar or He for shielding, which reduces Cr oxide formation and stabilizes the arc, enabling continuous and automatic welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-Cr steel is used for welding material to achieve excellent high-temperature strength, then mechanical performance is improved, but Cr oxide forms on molten pool surface causing welding defects
Solution Approach 1:
The patent uses inert shielding gases (Ar, He, or their mixtures with CO2 and O2 controlled within specific ranges) to create an inert atmosphere during welding, preventing Cr oxide formation on the molten pool surface while maintaining the high-Cr steel composition for excellent high-temperature strength
Solution Approach 2:
The patent optimizes the chemical composition parameters of both the welding wire (Cr: 8-15%, C: 0.05-0.15%, Si: 0.10-0.50%, Mn: 1.50-3.00%, Mo: 0.10-1.00%, Ni: 0.10-1.00%, REM: 0.005-0.050%) and shielding gas (O2: 0.10-5.00%, CO2: 0.50-30.00%, Ar: 65-99.00%, He: 1-35.00%) to control Cr oxide formation while maintaining mechanical performance
2Productivity
If GMAW is performed on high-Cr steel to improve welding efficiency, then welding speed is increased, but arc deflection occurs due to cathode point dispersion from Cr oxide
Solution Approach 1:
The patent employs inert shielding gas atmospheres with controlled composition (Ar-based or He-based with limited CO2 and O2) to prevent Cr oxide formation during GMAW, eliminating cathode point dispersion and arc deflection while maintaining high welding efficiency and automation capability
3Strength
If Cr content is increased to 8.0-14.0% to improve mechanical strength, then high-temperature strength is enhanced, but Cr oxide generation increases causing welding defects
Solution Approach 1:
The patent optimizes Cr content within 8-15% and carefully controls the composition of shielding gas (O2: 0.10-5.00%, CO2: 0.50-30.00%, Ar: 65-99.00%, He: 1-35.00%) to minimize Cr oxide generation while maintaining enhanced mechanical strength, using the inert atmosphere to counteract the increased oxide formation tendency from higher Cr content
Solution Approach 2:
The patent uses inert shielding gases (Ar, He) with controlled concentrations of reactive gases to create an atmosphere that prevents Cr oxidation even at high Cr contents (8-15%), allowing the material to achieve excellent mechanical strength without the harmful effects of excessive Cr oxide generation
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 effectively reduces welding defects such as lack of fusion and bad bead shapes, allowing for reliable automation of high-Cr steel welding in power boilers by controlling Cr oxide formation and maintaining arc stability.
Implementation Method 1
a gas shielded arc welding method using inert gases like Ar or He for shielding
Implementation Method 2
Gas-shielded arc welding wire and gas-shielded arc welding method
Data Source
AI summary
A gas shielded arc welding wire contains, based on total mass of the wire in terms of mass %: C: 0.01% to 0.50%; Si: 0.01% to 1.50%; Mn: 0.10% to 2.50%; Cr: 5% to 15%; Ni: 0.05% to 1.50%; Mo: 0.1% to 2.0%; V: 0.1% to 1.0%; Nb: 0.01% to 0.20%; REM: 0.001% to 0.050%; S: 0.0010% to 0.0200%; and O: 0.025% or less (including 0%), which satisfies the following relationship: 3.0≤(Nb+10×REM)/(S+O)≤200.0.