Arc Welded Overlap Joint With Low-Slag Corrosion Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing arc welded joints in automobiles, particularly those made from steel sheets with tensile strength less than 640 MPa, face challenges in maintaining strength in corrosive environments due to rusting and corrosion, which are not adequately addressed by existing techniques.
Innovation Solution
The solution involves specifying the throat thickness of the weld in relation to the base material steel sheet thickness, controlling the slag-covered area ratio, and using a shielding gas with a specific oxidizing gas composition to reduce slag formation and enhance corrosion resistance, while also employing intermittent short-circuiting and pulse current welding to stabilize the weld bead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the throat of the weld is increased to improve joint strength, then the joint strength is improved, but the amount of slag attached to the weld increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the throat dimension within the range 0.5t≤a≤1.8t and managing the oxidizing gas content in shielding gas (2×[O2]+[CO2]≤5). By adjusting these parameters, the weld achieves sufficient joint strength while minimizing slag attachment, resolving the contradiction between strength improvement and harmful slag formation.
2Strength
If steel sheets with higher tensile strength are used to improve joint strength, then the joint strength is improved, but the cost and manufacturability decrease
Solution Approach 1:
The patent changes the parameter of throat dimension to a specific range (0.5t≤a≤1.8t) that enables adequate joint strength with conventional steel sheets having tensile strength of 440 MPa or more. This approach eliminates the need for expensive high-strength steel (640 MPa or more), thereby improving manufacturability and cost-effectiveness while maintaining sufficient joint strength.
3Stress or pressure
If the throat is increased to improve allowable stress, then the allowable stress is improved, but the weld geometry becomes more complex
Solution Approach 1:
The patent applies parameter changes by defining the throat within the optimal range 0.5t≤a≤1.8t, which balances allowable stress improvement with geometric simplicity. This parameter control ensures sufficient load-bearing capacity while avoiding excessive geometric complexity that would complicate welding operations and quality 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
This approach ensures stable joint strength and prevents rusting, maintaining the weld's integrity even in corrosive environments by optimizing the throat thickness, reducing slag formation, and enhancing chemical convertibility and electrodeposition coatability.
Implementation Method 1
a weld bead 6 in an overlap 4 of the steel sheets 3 by arc welding
Implementation Method 2
forming a weld by arc welding of an overlap of at least two steel sheets
Implementation Method 3
using a shielding gas including Ar gas and an oxidizing gas
Data Source
AI summary
An arc welded joint and an arc welding method. The arc welded joint has a weld formed by arc welding of an overlap of at least two steel sheets. The throat in the weld and the sheet that is uppermost among the steel sheets satisfy a specified relationship. In a region extending 2.0 mm from a bead toe of the weld in a weld metal direction and also extending 2.0 mm from the bead toe in a base material direction, a slag-covered area ratio is 50% or less.