Shear-Assisted Co-Extrusion of Multi-Metal Tubes With Bonded Interfaces
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Solution Overview
Problem
Existing methods for co-extrusion of multi-metallic materials are expensive, result in non-uniform material flow, require elaborate billet fabrication, and face challenges with bonding at the interface, especially for materials like 1100 and 7075AI, and thermal spray coatings are limited by cracking and spallation.
Innovation Solution
Shear-assisted extrusion assemblies and methods that utilize a billet assembly with distinct materials and a tool to create a high shear region, allowing for the production of multi-metallic tubes with controlled thickness ratios and bonded interfaces, avoiding the need for elaborate billet fabrication and heat treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hydrostatic extrusion or indirect extrusion is used for co-extrusion, then multi-metallic materials can be produced, but the process becomes expensive and results in non-uniform material flow
Solution Approach 1:
A shear-assisted tool is introduced as an intermediary element between the billet and die. This tool creates a high shear region that acts as a mediator to control and uniformize material flow during co-extrusion, resolving the non-uniform flow problem while maintaining ease of manufacture
Solution Approach 2:
The invention changes the stress state parameters by introducing high shear conditions through the shear-assisted tool. By modifying the mechanical parameters (shear stress, pressure distribution) in the extrusion zone, uniform material flow is achieved without requiring expensive conventional extrusion methods
2Reliability
If elaborate billet fabrication steps and billet preheating are employed, then desirable bonding at the interface can be obtained, but the process complexity and energy consumption increase
Solution Approach 1:
The shear-assisted tool is designed to create the high shear region and promote interface bonding during the extrusion process itself, eliminating the need for preliminary billet fabrication steps and preheating treatments. The bonding action is performed in-situ during extrusion
Solution Approach 2:
The invention replaces thermal processing (preheating) and complex mechanical fabrication steps with a mechanically-driven shear-assisted extrusion process. The high shear stress mechanically promotes interface bonding without requiring thermal softening or elaborate billet preparation
3Reliability
If thermal spray coatings are applied, then surface protection can be achieved, but the coatings are limited to thin layers that crack and spall due to thermal stresses
Solution Approach 1:
Instead of applying separate thermal spray coatings, the invention creates a composite multi-metallic structure through co-extrusion where different metal layers are bonded together. This metallurgically-bonded composite structure inherently handles thermal stresses better than thin surface coatings, preventing cracking and spallation
4Adaptability or versatility
If conventional extrusion methods are used for challenging material combinations like 1100 and 7075AI, then co-extrusion can be attempted, but bonding at the interface becomes difficult
Solution Approach 1:
The shear-assisted tool changes the stress state parameters during extrusion by creating high shear conditions. This parameter change enables interface bonding between dissimilar materials (like 1100 and 7075AI) that have different flow stresses, making the process adaptable to challenging material combinations while ensuring reliable bonding
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
Facilitates the production of multi-metallic tubes with sound bonding and variable thicknesses, enabling easy joining to other structures and minimizing thermal stresses, while overcoming difficulties in extruding challenging material combinations like 1100 and 7075/2024AI.
Implementation Method 1
shear-assisted force to a tool operably engaged with the billet to form an extrudate
Data Source
AI summary
Shear-assisted extrusion assemblies are provided. The assemblies can include a billet containing assembly containing a billet comprising a billet outer material and a billet inner material in at least one cross-section; a tool operably engaged with the billet; an extrudate receiving channel configured to receive extrudate from the tool, wherein the extrudate comprises extruded outer material and extruded inner material in at least one cross-section, the extruded outer material being the same material as the billet outer material, and the extruded inner material being the same as the billet inner material. Methods for producing multi-material shear-assisted extrudate are also provided.