AA6066 Aluminum Alloy for High-Pressure Hydrogen Storage
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Solution Overview
Problem
Current aluminum alloys used in high-pressure hydrogen gas storage containers face challenges with hydrogen embrittlement and strength, particularly with the AA6066 alloy, which requires improved resistance and higher strength to reduce liner thickness and weight while maintaining reliability.
Innovation Solution
An aluminum alloy composition with specific ranges of Mg, Si, Fe, Cu, Mn, Cr, Zn, and Ti is developed, including a T6 tempering treatment, to enhance resistance to hydrogen embrittlement and mechanical properties, with a focus on dispersing fine particles and minimizing coarse crystallized materials to improve strength and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pressure employed for filling hydrogen gas into the storage container is increased, then the storage capacity is improved, but the aluminum alloy material becomes embrittled and loses reliability
Solution Approach 1:
The invention changes the chemical composition parameters of the AA6066 aluminum alloy by precisely controlling the content ranges of Mg (0.8-1.4%), Si (0.9-1.8%), Fe (<0.44%), Cu (0.05-1.2%), Mn (0.2-0.9%), Cr (0.40% or less), Zn (0.25% or less), and Ti (0.20% or less). This compositional parameter optimization resolves the contradiction by creating an alloy that maintains both high strength for pressure containment and excellent resistance to hydrogen embrittlement, enabling safe storage at higher pressures without embrittlement
2Strength
If the strength of the aluminum alloy liner is increased to reduce thickness, then the weight is reduced, but the resistance to hydrogen embrittlement deteriorates
Solution Approach 1:
The invention optimizes the chemical composition parameters within specific ranges to achieve a balance between strength and hydrogen embrittlement resistance. The controlled addition of alloying elements creates a microstructure that provides both high mechanical strength (tensile strength ≥410 MPa, yield strength ≥360 MPa) and excellent resistance to hydrogen embrittlement, eliminating the need to sacrifice reliability for weight reduction
Solution Approach 2:
The invention creates a composite microstructure within the aluminum alloy by controlling the formation of dispersed particles through specific alloy composition. This internal composite structure, with fine dispersed particles distributed throughout the matrix, provides both strengthening mechanisms and hydrogen trapping sites, simultaneously improving strength and hydrogen embrittlement resistance
3Strength
If the content of major elements (Zn, Mg, Cu) is increased to improve strength, then the tensile strength is improved, but stress corrosion cracking occurs and production defects increase
Solution Approach 1:
The invention precisely controls the content parameters of major alloying elements within optimized ranges: Mg (0.8-1.4%), Si (0.9-1.8%), Cu (0.05-1.2%). This parameter optimization prevents excessive element accumulation that would cause stress corrosion cracking while maintaining high strength properties. The balanced composition ensures tensile strength ≥410 MPa without compromising SCC resistance or causing production defects like billet cracking
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
The optimized AA6066 alloy composition achieves improved tensile strength, yield strength, and elongation, while maintaining excellent resistance to hydrogen embrittlement, making it suitable for high-pressure hydrogen gas storage containers.
Implementation Method 1
the 6066 aluminum alloy material is required to have resistance to hydrogen embrittlement such that the 6066 aluminum alloy material does not embrittle even when the pressure employed for filling a hydrogen gas into a storage container for high-pressure hydrogen gas is increased
Implementation Method 2
T6 tempering treatment... with a remaining portion including Al and unavoidable impurities, wherein a relationship between C and D satisfies the formula: D+0.00×C-9.5 ≤ 0 when D represents the average density (particles/μm2
Data Source
Figure 1
AI summary
An object of the present invention is to provide a 6000-series aluminum alloy material for a high-pressure gas container which has both of resistance to hydrogen embrittlement and mechanical properties. In the aluminum alloy material for a high-pressure gas container, the contents of Fe, Mn and Cu fall within narrower ranges than the standard composition of AA6066 alloy. The aluminum alloy material is produced to have a structure in which a predetermined amount of fine dispersed particles are dispersed therein and coarse crystallized materials are small, and therefore strength and resistance to hydrogen embrittlement are improved, which are required for a high-pressure gas container.