Laser Welding Flange End Faces With a Degassing Gap
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Solution Overview
Problem
Existing laser welding methods for metal-coated components, particularly those with zinc coatings, face issues such as zinc degassing leading to spatter formation, increased porosity, and material embrittlement, which compromise weld quality and strength, especially under dynamic loads, and require complex clamping and energy inefficiencies.
Innovation Solution
The method involves positioning the joining flanges at an angle to each other, creating a degassing gap that directs vaporization products away from the weld pool, allowing for controlled degassing and efficient energy input, with the laser beam angled to enhance preheating and penetration, and optionally using oscillatory motion to improve weld quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If laser welding is performed on metal-coated components (e.g., zinc-coated steel), then welding depth and penetration can be achieved, but zinc degassing occurs causing spatter formation, increased porosity, and material embrittlement
Solution Approach 1:
The method performs preliminary degassing of the zinc coating before the steel base material melts. By controlling the laser parameters and welding speed, the zinc coating is vaporized and removed in advance, preventing it from contaminating the weld pool and causing porosity and embrittlement. This preliminary action resolves the contradiction by eliminating the harmful zinc degassing effects while maintaining the desired welding depth and strength.
Solution Approach 2:
The method changes the laser welding parameters (power, speed, focus position) to create a specific thermal regime where the zinc coating vaporizes at a controlled rate before steel melting occurs. By adjusting these parameters, the process transforms the harmful zinc degassing into a controlled preliminary vaporization stage, eliminating spatter and porosity while achieving the required penetration depth and weld strength.
2Reliability
If laser beam oscillation is used to control degassing, then zinc vaporization can be managed, but welding speed is limited reducing productivity
Solution Approach 1:
The method extracts the degassing function from the oscillation process itself. Instead of using oscillation to control degassing, the method separates degassing (achieved through preliminary laser heating and parameter control) from the main welding process. This allows continuous forward motion at high speed while degassing occurs independently in the preliminary stage, resolving the contradiction between reliable degassing control and high welding productivity.
3Reliability
If a gap is maintained between joining flanges for degassing, then zinc vapor can escape, but laser energy is lost through the gap reducing welding efficiency
Solution Approach 1:
The method applies local quality by creating different conditions in different zones: in the preliminary heating zone, the laser creates controlled vaporization channels for zinc escape, while in the main welding zone, the joining flanges remain in close contact to minimize energy loss. This spatial differentiation of conditions allows effective degassing where needed while maintaining welding efficiency where the laser energy must be concentrated, resolving the contradiction between degassing effectiveness and energy utilization.
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 results in a high-quality, pore-free weld with improved strength, enabling faster welding speeds and reduced component weight and installation space, while protecting the laser optics from contamination.
Implementation Method 1
the metallic coating material has an evaporation temperature below the melting point of the steel material and thus the coating material spontaneously and explosively vaporizes due to the heat input required for welding
Implementation Method 2
the melting point and vaporization temperature of the metallic coating are significantly lower than the melting point of the steel
Implementation Method 3
laser welding is used for this purpose
Data Source
Figure 1a~1c
Figure 2a~2c
Figure 3a~3c
AI summary
The invention relates to a method for laser welding the end faces of joints (2, 2.1) of two connecting flanges, which are held against each other, of two connecting partners (1, 1.1) made from a steel material, of which at least one is provided with a metallic coating with an evaporation temperature that is below the melting temperature of the steel material. The method is carried out such that, for the process of laser welding, the connecting flanges (1, 1.1) of the two connecting partners (1, 1.1) are held against each other enclosing an angle that opens pointing in a direction from the joint side on which the laser is applied, as a result of which a degassing gap (5), which increases in the direction of heat introduction, is provided between the connecting flanges (3, 3.1), through which degassing gap evaporation products of the coating material (8, 8.1) resulting from the introduction of heat are carried off.