Aluminum Alloy Clad Material for Aircraft Fatigue Resistance
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Solution Overview
Problem
Aluminum-alloy materials used in aircraft structures face limitations in enhancing both static strength and fatigue characteristics, with existing compositions struggling to balance strength and corrosion resistance effectively.
Innovation Solution
An aluminum-alloy clad material with a core composition of Cu: 3.8-4.9 mass %, Mg: 1.2-1.8 mass %, Mn: 0.3-0.9 mass %, and a skin material with 99.5 mass % Al purity, where the number density of microvoids is 100/mm2 or less, is developed to improve static strength and fatigue resistance while maintaining corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Al-Cu-Mg alloy composition is adjusted to increase static strength, then tensile strength is improved, but fatigue characteristics deteriorate due to increased microvoid formation
Solution Approach 1:
The invention applies local quality by creating a dual-layer structure where the core material provides high strength through optimized Al-Cu-Mg composition while the skin material provides high purity aluminum to prevent microvoid formation. This local differentiation allows each layer to perform its specific function optimally without compromising the other.
Solution Approach 2:
The invention uses composite materials by combining two different aluminum alloys with distinct properties - a high-strength core alloy (Al-4.0-5.0Cu-1.5-2.5Mg) and a high-purity skin alloy (Al-99.5% or higher). This composite structure resolves the contradiction by allowing the core to provide static strength while the skin protects against fatigue-induced microvoid formation.
2Reliability
If high-purity aluminum skin is coated on Al-Cu-Mg alloy core, then corrosion resistance is improved, but manufacturing complexity increases due to clad bonding process requirements
Solution Approach 1:
The invention applies parameter changes by optimizing the chemical composition parameters of both core and skin materials, as well as the thermal processing parameters (heating temperature 400-500°C, holding time 1-10 hours). These controlled parameter changes enable the clad bonding process to achieve reliable corrosion protection while maintaining manufacturability through standardized thermal treatment conditions.
3Strength
If Cu and Mg content in core material is increased to enhance strength, then static strength is improved, but microvoid density increases leading to poorer fatigue characteristics
Solution Approach 1:
The invention applies segmentation by dividing the material into two distinct functional layers - the core material contains the Cu and Mg alloying elements necessary for high strength, while the skin material is segregated as high-purity aluminum that prevents microvoid formation. This spatial segmentation allows high alloy content in the core without compromising fatigue characteristics, as the skin layer acts as a protective barrier.
Data Source
AI summary
An aluminum-alloy clad material includes a skin layer clad to and covering at least one surface of a core layer. The core layer is composed of an aluminum alloy containing Cu: 3.8-4.9 mass %, Mg: 1.2-1.8 mass % and Mn: 0.3-0.9 mass %. The core layer has an area number density of microvoids that have a circle-equivalent diameter of 0.5 μm or greater that is 100/mm2 or less. The skin layer has an Al purity of 99.5 mass % or greater. A method of manufacturing a wrought material from such an aluminum-alloy clad material includes heating the wrought material to the solution heat treatment temperature of the core layer at a temperature-rise rate of 50° C.-200° C./h.