Copper Laser Welding with Reactive Braze Material
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Solution Overview
Problem
Conventional welding methods, such as TIG and laser welding, face challenges when joining copper workpieces, particularly exhibiting poor penetration and fatigue performance, and causing thermal damage to nearby insulation due to high thermal input and conductivity.
Innovation Solution
A method involving the use of a reactive braze material at the joining surfaces of copper workpieces, heated by dual or hybrid laser beams to form a liquid-containing reaction product below the solidus temperature, creating a solid-state welded joint while minimizing thermal damage to insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional laser welding or TIG welding is used to join copper workpieces, then welding penetration and joint strength are improved, but thermal damage to nearby insulation occurs due to high thermal input and copper's high thermal conductivity
Solution Approach 1:
The patent changes the thermal process parameters by using reactive braze materials that lower the processing temperature. Instead of melting copper directly (requiring temperatures above 1085°C), the reactive braze creates intermetallic compounds at lower temperatures (below the solidus temperature of copper), reducing thermal input and preventing damage to nearby insulation while still achieving strong joints
Solution Approach 2:
The reactive braze material acts as an intermediary substance between the copper workpieces. This intermediate layer facilitates bonding through chemical reaction and intermetallic compound formation, allowing joint strength to be achieved without directly melting the copper base metal, thereby reducing thermal damage to surrounding insulation
2Strength
If high thermal input is applied to achieve adequate weld penetration in copper, then joint strength is improved, but fatigue performance deteriorates due to thermal damage and poor penetration control
Solution Approach 1:
The patent changes the thermal process parameters by using reactive braze materials that lower the processing temperature. Instead of melting copper directly (requiring temperatures above 1085°C), the reactive braze creates intermetallic compounds at lower temperatures (below the solidus temperature of copper), reducing thermal input and preventing damage to nearby insulation while still achieving strong joints
Solution Approach 2:
The reactive braze material acts as an intermediary substance between the copper workpieces. This intermediate layer facilitates bonding through chemical reaction and intermetallic compound formation, allowing joint strength to be achieved without directly melting the copper base metal, thereby reducing thermal damage to surrounding insulation
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 enhances weld penetration and fatigue strength by forming a sound joint without fully melting the copper, reducing thermal damage to insulation, and improving the reliability of copper welds in automotive and other applications.
Implementation Method 1
The reactive material is selected to react upon being heated to a temperature below the solidus temperature of the first and second workpieces to form a liquid-containing reaction product
Implementation Method 2
The second workpiece is then heated at an upper surface thereof with a first, green laser beam and at a lower surface thereof with a second, infrared laser beam
Data Source
AI summary
A method of forming a weld interface between a first workpiece and a second workpiece includes arranging a reactive braze material at a first joining surface of the first workpiece. The reactive material is selected to react upon being heated to a temperature below the solidus temperature of the first and second workpieces to form a liquid-containing reaction product. Furthermore, an assembly is prepared of the first workpiece and the second workpiece with the first joining surface of the first workpiece and a second joining surface of the second workpiece separated by the reactive material. The second workpiece is then heated with a first laser beam following a first path and with a second laser beam following a second path.