Arc Weld Composition and Bead Geometry for Fatigue-Resistant Joints
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Solution Overview
Problem
Existing welding technologies for high-strength steel components in vehicles face issues such as stress concentration, corrosion, and reduced durability due to notch effects, corrosion resistance, and welding defects, which compromise the fatigue characteristics and economic efficiency.
Innovation Solution
A gas shielded arc welding member with controlled alloy compositions and bead shapes, including specific ranges of C, Si, Mn, Cr, and other elements, along with defined relationships for weld bead geometry, to enhance fatigue lifespan and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If high-strength steel materials are used to reduce component weight, then weight reduction is achieved, but durability under repeated fatigue loads deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the weld zone (C: 0.05-0.20%, Si: 0.01-1.00%, Mn: 1.50-3.00%, P: 0.030% or less, S: 0.030% or less, Cr: 1.50% or less, Mo: 0.60% or less, Al: less than 0.10%, Ni: 0.40% or less, Ti: less than 0.10%, Nb: 0.10% or less, V: 0.10% or less, B: 0.01% or less) to achieve optimal mechanical properties. This compositional control enables the weld zone to maintain high strength while improving fatigue resistance, thus resolving the contradiction between weight reduction and durability.
Solution Approach 2:
The patent creates a composite material system by forming a weld zone with specific alloy composition on high-strength steel base materials (340-1500 MPa). The weld zone acts as a composite structure with optimized properties different from the base material, allowing the overall component to achieve both light weight and high durability under fatigue loads.
2Strength
If arc welding is used to secure strength in chassis components, then strength is improved, but fatigue characteristics deteriorate due to stress concentration at bead ends
Solution Approach 1:
The patent changes the chemical composition parameters of the weld zone to optimize both strength and fatigue characteristics. By controlling C content at 0.05-0.20% and Si content at 0.01-1.00%, the weld metal achieves adequate strength while reducing brittleness and improving ductility, which reduces stress concentration effects and improves fatigue performance.
Solution Approach 2:
The patent applies local quality by creating a weld zone with specifically tailored composition that differs from the base material. The weld zone contains controlled amounts of alloying elements (Mn: 1.50-3.00%, Cr: 1.50% or less, Mo: 0.60% or less) to achieve local optimization of mechanical properties, particularly improving the transition zone properties to reduce stress concentration and enhance fatigue resistance.
3Reliability
If plated steel materials are used for rust prevention, then corrosion resistance is improved, but welding quality deteriorates due to pore defects from zinc vapor generation
Solution Approach 1:
The patent changes the chemical composition parameters of the weld zone to compensate for the presence of plating materials. By controlling Si content at 0.01-1.00% and Al content at less than 0.10%, the weld zone achieves adequate deoxidation to prevent excessive pore formation from zinc vapor, while maintaining corrosion resistance. The controlled Mn content (1.50-3.00%) also helps stabilize the weld metal composition despite plating interference.
4Productivity
If gas shield arc welding is used on plated steel, then welding efficiency is maintained, but corrosion resistance deteriorates due to slag generation causing painting defects
Solution Approach 1:
The patent changes the chemical composition to reduce slag generation. By controlling Si content at 0.01-1.00% (lower range) and using controlled deoxidation with Al (less than 0.10%), the weld zone produces minimal slag that would cause painting defects. This allows gas shield arc welding to proceed efficiently while maintaining good surface quality and corrosion resistance after painting.
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 provides a welding member with improved low-cycle and high-cycle fatigue lifespan, reduced susceptibility to corrosion, and enhanced welding productivity, ensuring economic feasibility for lightweight chassis components.
Implementation Method 1
gas shielded arc welding member
Data Source
AI summary
A welding member having excellent weld fatigue characteristics is provided. The present disclosure can provide a gas shielded arc welding member that can secure excellent fatigue characteristics in an automotive industry.