Gas-Shielded Arc Welding Composition for Fatigue and Corrosion Resistance
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Solution Overview
Problem
High-tensile steel welding faces challenges in achieving fatigue resistance and corrosion resistance due to oxidation issues with Mn and Si, and high costs associated with Ni and Mo, which result in reduced fatigue strength and increased rust risks in welded structures.
Innovation Solution
A gas-shielded arc welding method using a consumable electrode with controlled compositions of C, Si, Mn, Cr, S, and Ni, and a shielding gas with specific CO2 and O2 levels, optimizing the welding conditions to balance Cr content and shielding gas composition for improved fatigue and corrosion resistance while minimizing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Mn and Si are added to improve fatigue strength, then fatigue resistance is improved, but slag forms that is hard to peel off and causes rust
Solution Approach 1:
The patent optimizes the chemical composition parameters by limiting Mn to 0.05-2.00% and Si to 0.05-2.00%, and crucially adding Ti to 0.01-0.50%. This parameter change introduces Ti which forms low-melting-point slag that peels off easily, resolving the harmful slag adhesion problem while maintaining the fatigue strength benefits of Mn and Si
Solution Approach 2:
Ti acts as an intermediary element that modifies the slag characteristics. The Ti-containing slag has different properties than conventional Mn-Si slag, specifically lower melting point and better peelability, thus mediating between the need for fatigue strength enhancement and the need for clean weld surfaces
2Strength
If Ni and Mo are added in large amounts to reduce martensite transformation point and tensile residual stress, then fatigue property is improved, but cost increases
Solution Approach 1:
The patent replaces expensive Ni (0.50-5.00% limited) and Mo (0.10-1.00% limited) with more cost-effective alternatives. The use of Ti (0.01-0.50%) and optimized Cr (0.10-3.00%) provides similar benefits at lower cost, effectively substituting expensive elements with cheaper ones that achieve the same functional goals
Solution Approach 2:
The patent changes the compositional parameters by setting specific ranges for Ni and Mo that are lower than conventional amounts, while introducing Ti and optimizing Cr content. This parameter optimization achieves the desired reduction in martensite transformation point and residual stress at reduced material cost
3Reliability
If Cr content is increased to improve fatigue resistance and coating property, then corrosion resistance is improved, but welding conditions become more difficult to control
Solution Approach 1:
The patent optimizes Cr content to a specific range of 0.10-3.00% and introduces Ti at 0.01-0.50%. This controlled parameter change ensures sufficient corrosion resistance while avoiding excessive Cr that would complicate welding. The Ti addition further facilitates slag removal, simplifying the overall welding process control
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 method achieves excellent fatigue resistance and corrosion resistance in welded high-tensile steel plates with a tensile strength of 780 MPa or more, reducing the risk of rust and cracking, while maintaining low production costs.
Implementation Method 1
flowing a shielding gas... the shielding gas includes, in vol. %, at least one selected from CO2 and O2: 1% to 15% in total
Implementation Method 2
welding a steel plate having a tensile strength of 780 MPa or more while feeding a consumable electrode via a welding torch and flowing a shielding gas
Implementation Method 3
gas-shielded arc welding method... welding is performed under the condition satisfying the following relationship
Data Source
AI summary
A gas-shielded arc welding method includes welding a steel plate having a tensile strength of 780 MPa or more while feeding a consumable electrode via a welding torch and flowing a shielding gas. The consumable electrode includes, in mass %, C: 0 to 0.20%, Si: 0 to 0.50%, Mn: 0 to 0.50%, Cr: 1.00% to 9.00%, S: 0.0020% to 0.0600%, and Ni: 0 to 0.50%. The shielding gas includes, in vol. %, at least one of CO2 and O2: 1% to 15% in total, with the remainder being Ar and unavoidable impurities. Welding is performed under the condition satisfying the relationship of 1≤{−0.05×[CO2+O2]}+[Cr]≤8.3, and [Cr] represents the content of Cr in the consumable electrode, and [CO2+O2] represents a total content of at least one of CO2 and O2 in the shielding gas.