Weld-Brazed Aluminum-Titanium Joint with Tapered Chamfer
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Solution Overview
Problem
Current methods for joining aluminum alloys to titanium alloys in the aerospace industry face challenges in achieving high mechanical strength and efficient processing, with existing weld-brazing techniques resulting in joints with limited strength and large heat-affected zones.
Innovation Solution
A process involving chamfering the titanium alloy edge into a tapered truncated shape and using a filler metal with inert gas to create a weld-brazed joint, where the chamfer angles and thickness are optimized to enhance contact surface and melt flow, allowing for heating above the aluminum melting point but below the titanium point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If fusion welding is used to join aluminum and titanium alloys at temperature above titanium melting point, then complete fusion of both materials is achieved, but titanium-aluminum compounds are produced in large quantities resulting in poor mechanical strength lower than 100 MPa
Solution Approach 1:
The patent changes the temperature parameter from above titanium melting point to a controlled range above aluminum melting point but below titanium melting point. This parameter change prevents excessive titanium-aluminum compound formation while ensuring complete aluminum fusion, thereby improving joint strength from below 100 MPa to above 260 MPa.
Solution Approach 2:
The patent introduces a filler metal as an intermediary material in the joint. This filler metal mediates the bonding between aluminum and titanium base metals, controlling the composition of the fusion zone and reducing harmful titanium-aluminum intermetallic compound formation, thus achieving superior mechanical strength.
2Strength
If weld-brazing is used to join aluminum and titanium alloys, then joint strength is improved to above 260 MPa, but large heat-affected zones are created reducing welding speed
Solution Approach 1:
The patent applies local quality by creating a tapered truncated chamfer geometry on the titanium alloy edge with specific dimensions (angles α1 and α2 between 0° and 50°, minimum thickness t between 0.05e and 0.3e). This localized geometric modification concentrates the heat input and fusion zone in a controlled manner, achieving high joint strength while minimizing the overall heat-affected zone size to enable faster welding speeds.
3Ease of manufacture
If diffusion welding is used to join titanium and aluminum alloys, then processing is simplified, but the strength of the assembly is lower than 100 MPa
Solution Approach 1:
The patent utilizes phase transitions by heating the materials to temperatures above the aluminum melting point to achieve complete fusion of the aluminum alloy. This liquid-phase welding approach, combined with controlled cooling, produces a metallurgical bond with strength exceeding 260 MPa, significantly improving upon diffusion welding while maintaining process simplicity.
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 process achieves higher ultimate tensile strength (>260 MPa) and reduced heat-affected zones, enabling faster welding speeds and improved joint quality, suitable for aerospace applications such as aircraft seat tracks.
Implementation Method 1
heating the surface areas of said members adjacent the abutment to a temperature above the melting temperature of said aluminium alloy and below the melting temperature of said titanium alloy
Implementation Method 2
When the melt solidifies, titanium-aluminium compounds are produced
Implementation Method 3
heating the surface areas of said members adjacent the abutment to a temperature above the melting temperature of said aluminium alloy and below the melting temperature of said titanium alloy, in the presence of an inert gas
Implementation Method 4
heating the surface areas of said members adjacent the abutment to a temperature above the melting temperature of said aluminium alloy
Data Source
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AI summary
The invention concerns a process for joining a first member (1) comprising an aluminium alloy to a second member (2) comprising a titanium alloy and having at least one edge with a thickness e, comprising the steps of (i) chamfering said edge of said second member into a tapered truncated shape having on a first side a first tapering angle al, on a second side a second tapering angle a2 and a minimum thickness t, wherein a1 and a2 are greater than or equal to zero, the sum of a1 and a2 is between 10° and 50° and t is between 0.05 e and 0.3 e, (ii) placing said first member and said chamfered edge of said second member (21) in an abutting relationship defining a geometry to be weld-brazed (3), (iii) heating the surface areas of said members adjacent the abutment to a temperature above the melting temperature of said aluminium alloy and below the melting temperature of said titanium alloy, in the presence of an inert gas (5) and of a filler metal (4) to obtain a weld-brazed joint. The process of the invention is particularly useful for obtaining high strength weld- brazed joints between aluminium and titanium with a high process output.