Al Alloy Compressor Impeller High-Temperature Strength
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Solution Overview
Problem
Conventional aluminum alloy compressor impellers for turbochargers face issues with deformation and fatigue failure at high operating temperatures, and existing solutions that use multiple materials for different parts are not industrially viable due to productivity and cost concerns.
Innovation Solution
An aluminum alloy cast impeller with a specific composition (Cu: 1.4-3.2%, Mg: 1.0-2.0%, Ni: 0.5-2.0%, Fe: 0.5-2.0%, Ti: 0.01-0.35%) and controlled secondary dendrite arm spacing distribution, produced through pressure casting and heat treatment, to achieve high-temperature strength and improved casting yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an aluminum alloy composition of more desirable high-temperature strength (e.g., JIS-AC1B Al-5% Cu-0.3% Mg alloy) is used, then high-temperature strength is improved, but the molten metal lacks desirable fluidity and tends to cause misruns (underfilling) in thin blade parts
Solution Approach 1:
The invention changes the chemical composition parameters of the aluminum alloy by adding specific amounts of Ni (0.5-2.0 mass%) and Fe (0.5-2.0 mass%) to the base Al-Cu-Mg alloy. This parameter modification improves both the high-temperature strength and the fluidity of the molten metal, eliminating the misrun problem while maintaining structural integrity at elevated temperatures.
Solution Approach 2:
The invention creates a composite alloy system by combining multiple elements (Al, Cu, Mg, Ni, Fe) in specific proportions. This composite material approach allows the alloy to exhibit both good castability and high-temperature strength, resolving the contradiction between ease of manufacture and strength requirements.
2Ease of manufacture
If conventional easily castable aluminum alloys (e.g., JIS-AC4CH Al-7% Si-0.3% Mg alloy) are used, then castability is improved, but the impeller causes deformation and fatigue failure during use at high temperatures
Solution Approach 1:
The invention modifies the alloy composition by reducing Si content (0.3 mass% or less) and adding specific amounts of Cu (1.4-3.2 mass%), Mg (1.0-2.0 mass%), Ni (0.5-2.0 mass%), and Fe (0.5-2.0 mass%). This parameter change transforms the alloy from a conventional easily castable but weak material to one that maintains both castability and high-temperature strength.
3Strength
If different materials are used for different parts (blade part, boss, disc part) and coalesced or joined together, then high-temperature strength is improved, but productivity and cost are adversely affected
Solution Approach 1:
The invention uses a single homogeneous aluminum alloy composition for the entire impeller structure, eliminating the need for multi-material construction. This homogeneous material approach maintains high-temperature strength while significantly improving productivity by simplifying the manufacturing process to a single casting operation without complex joining or coalescing steps.
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 solution provides a compressor impeller that maintains stable high-temperature strength up to 200°C for extended periods without deformation or fatigue failure, with a 0.2% proof stress value of 260 MPa or more, and enhances productivity by improving casting yield and reducing defects.
Implementation Method 1
the Al alloy casting is obtained by pressure casting
Implementation Method 2
an aluminum alloy cast impeller for compressors having a 0.2% proof stress value of 260 MPa or more at 200°C
Data Source
Figure 1~2
AI summary
Provided is an aluminum alloy cast impeller for compressors that shows stable high-temperature strength at operating temperatures of about 200°C, and that has excellent productivity. The Al alloy cast impeller for compressors is configured to include a boss part, a plurality of blade parts, and a disc part. The Al alloy cast impeller for compressors is formed of an Al alloy cast that contains Cu: 1.4 to 3.2 mass% (hereinafter, "%"), Mg: 1.0 to 2.0%, Ni: 0.5 to 2.0%, Fe: 0.5 to 2.0%, and Ti: 0.01 to 0.35%. The boss part, the blade parts, and the disc part have secondary dendrite arm spacings of 20 to 50 µm, 10 to 35 µm, and 5 to 25 µm, respectively, and satisfy the relationship Amax > Bmax > Cmax, where Amax, Bmax, and Cmax are the maximum values of the secondary dendrite arm spacings of the boss part, the blade parts, and the disc part, respectively. The Al alloy cast impeller for compressors has a 0.2% proof stress value of 260 MPa or more at 200°C. A method for producing the aluminum alloy cast impeller for compressors is also disclosed.