Angled Flange End-Face Laser Welding for Coated Steel Joints
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Solution Overview
Problem
Laser welding of sheet steel components with metallic coatings, such as zinc, faces challenges due to the lower evaporation temperature of the coating compared to the steel, leading to explosive degassing, increased porosity, and residual stresses, which compromise the weld's strength, especially under dynamic loads.
Innovation Solution
The method involves holding the connecting flanges at an angle to create a degassing gap that directs evaporation products away from the weld pool, allowing for controlled degassing and minimizing porosity, enabling higher feed rates and improved weld quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser welding is performed on sheet steel components with metallic coating, then welding can be achieved, but the coating material evaporates explosively causing increased porosity and spattering
Solution Approach 1:
The method applies preliminary action by pre-heating the coating material to a temperature between its evaporation temperature and the melting temperature of the steel base material before the actual welding process. This controlled pre-heating allows the coating to evaporate in a controlled manner rather than explosively during welding, significantly reducing porosity and spattering while maintaining weldability
Solution Approach 2:
The invention changes the temperature parameter dynamically during the welding process. By controlling the heating process in two stages - first heating to a temperature above the coating evaporation point but below steel melting point, then proceeding with welding - the method transforms the harmful explosive evaporation into a controlled process that improves weld quality
2Manufacturing precision
If higher energy input is applied to weld through coated steel, then weld depth increases, but coating evaporation and porosity increase
Solution Approach 1:
The method removes the coating material through controlled evaporation before the high-energy welding process begins. By pre-heating to evaporate the coating selectively, the subsequent welding operates on cleaner steel surfaces, achieving deeper penetration without the harmful effects of coating interference and explosive vaporization during the high-energy input phase
3Manufacturing precision
If laser welding is performed on galvanized sheets with gap maintenance, then zinc degassing is controlled, but laser energy is lost through the gap
Solution Approach 1:
The method performs preliminary evaporation of the zinc coating before welding, which eliminates the need to maintain gaps for degassing purposes. Once the coating is removed through controlled evaporation, the welding process can proceed with flanges in direct contact, eliminating laser energy loss through gaps while maintaining weld quality
4Ease of operation
If connecting flanges are held parallel during welding, then clamping is simplified, but laser energy is lost and degassing is problematic
Solution Approach 1:
By applying preliminary controlled evaporation to remove the coating before welding, the method eliminates the need for gap maintenance during welding. This allows flanges to be held in parallel contact position without energy loss, simplifying both clamping and the welding process while maintaining weld quality
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 pore-free weld with enhanced strength under static and dynamic loads, allowing for faster processing and reduced weight and space requirements in components, while maintaining high weld quality.
Implementation Method 1
for the process of laser welding, a laser beam is directed onto the connecting zone of the joints
Implementation Method 2
the steel material begins to melt
Implementation Method 3
the coating material spontaneously evaporates in an explosive manner, as a result of the introduction of heat required for welding
Data Source
AI summary
A method for laser welding the end faces of joints of two connecting flanges, which are held against each other, of two connecting partners 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 of the two connecting partners 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, which increases in the direction of heat introduction, is provided between the connecting flanges, through which degassing gap evaporation products of the coating material resulting from the introduction of heat are carried off.