Alpha-Beta Titanium Alloy Composition for High Specific Strength
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Solution Overview
Problem
Current high-strength titanium alloys used in aerospace applications, such as Ti-550, Ti-6246, and Ti-17, exhibit increased weight due to heavy alloying elements like Mo, Sn, and Zr, leading to higher costs and reduced specific strength compared to the baseline Ti-64 alloy, which is a concern for weight-sensitive components like rotating parts.
Innovation Solution
A novel alpha-beta titanium alloy, referred to as Timetal 575 or Ti-575, is developed with a composition of Al 4.7-6.0 wt.%, V 6.5-8.0 wt.%, Si 0.15-0.6 wt.%, Fe up to 0.3 wt.%, O 0.15-0.23 wt.%, and incidental impurities, achieving a higher yield strength and fracture toughness while maintaining ductility, through optimized heat treatment and processing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heavy alloying elements (Mo, Sn, Zr) are incorporated to increase strength, then strength is improved, but weight and cost increase
Solution Approach 1:
The patent changes the compositional parameters by replacing heavy elements (Mo, Sn, Zr) with lighter elements (Al, V, Si, Fe) in specific concentration ranges. This parameter substitution maintains strength while reducing density, directly resolving the contradiction between strength and weight
Solution Approach 2:
The patent creates a multi-element composite alloy system (Ti-Al-V-Si-Fe-O) where different elements contribute synergistic effects. Al and V provide strength, Si enhances high-temperature properties, Fe refines microstructure, and O controls phase stability. This composite approach achieves high strength without relying on heavy elements
2Strength
If heavy alloying elements (Mo, Sn, Zr) are incorporated to increase strength, then strength is improved, but cost increases
Solution Approach 1:
The patent changes the compositional parameters by substituting expensive heavy elements (Mo, Sn, Zr) with more cost-effective lighter elements (Al, V, Si, Fe). This parameter substitution maintains strength requirements while significantly reducing material cost
Solution Approach 2:
The patent employs more economical alloying elements (Al, V, Si, Fe) that are generally cheaper and more abundant than heavy elements (Mo, Sn, Zr). This substitution with more affordable materials reduces manufacturing cost while achieving the required mechanical properties
3Weight of moving object
If Ti-64 is used as baseline material, then cost and weight are reduced, but strength is insufficient for high-strength applications
Solution Approach 1:
The patent creates a composite alloy system (Ti-Al-V-Si-Fe-O) that builds upon the Ti-64 foundation by adding synergistic elements. Al and V provide solid solution strengthening, Si adds precipitation hardening capability, Fe refines grain structure, and O enhances phase stability. This composite approach achieves superior strength to Ti-64 while maintaining similar weight characteristics
4Strength
If higher strength alloys are used for rotating components, then strength is improved, but specific strength deteriorates due to weight increase
Solution Approach 1:
The patent optimizes compositional parameters by using lighter elements (Al density 2.7 g/cm³, V density 6.0 g/cm³) instead of heavy elements (Mo density 10.2 g/cm³, Sn density 7.3 g/cm³, Zr density 6.5 g/cm³). This parameter change increases strength while minimizing density increase, thereby improving specific strength (strength/density ratio) which is critical for rotating components
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A
AI summary
An alpha-beta titanium alloy comprising: Al at a concentration of from 4.7 wt.% to 6.0 wt.%; V at a concentration of from 6.5 wt.% to 8.0 wt.%; Si at a concentration of less than 1.0 wt.% ; O at a concentration of less than 1.0 wt.% ; and Ti and incidental impurities as a balance, wherein an Al/V ratio is from 0.65 to 0.8, the Al/V ratio being equal to the concentration of the Al divided by the concentration of the V in weight percent.