Near-beta Titanium Alloy Composition for Aviation Landing Gear
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Solution Overview
Problem
Conventional titanium alloys used in aviation components, such as Ti-555-3 and Ti-5Al-4.5V-2Mo-1Cr-0.6Fe, fail to consistently provide the required high strength, deep hardenability, and excellent ductility needed for critical applications like landing gear, due to inadequate oxygen content and overly broad weight percentage ranges, resulting in suboptimal strength-ductility combinations.
Innovation Solution
A high strength near-beta titanium alloy with specific weight percentage ranges of 5.3-5.7% aluminum, 4.8-5.2% vanadium, 0.7-0.9% iron, 4.6-5.3% molybdenum, 2.0-2.5% chromium, and 0.12-0.16% oxygen, along with a defined ratio of beta isomorphous to beta eutectoid stabilizers, molybdenum equivalence, and aluminum equivalence, which achieves superior tensile properties and fatigue resistance through solution heat treatment and precipitation hardening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional titanium alloys (e.g., Ti-555-3) are used to achieve high strength, then tensile strength can be improved, but ductility and deep hardenability deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the titanium alloy, specifically setting aluminum to 5.3-5.7%, vanadium to 4.8-5.2%, molybdenum to 4.6-5.3%, chromium to 2.0-2.5%, and iron to 0.7-0.9%. This precise parameter control optimizes the balance between strength, ductility, and hardenability, resolving the contradiction by finding the optimal composition window that simultaneously achieves high tensile strength and excellent ductility.
Solution Approach 2:
The patent creates a composite alloy system by combining multiple alloying elements (Al, V, Mo, Cr, Fe, O) in specific proportions to achieve synergistic effects. The interaction between these elements creates a complex microstructure that provides both high strength and excellent ductility, with the composite nature of the alloy allowing simultaneous optimization of properties that cannot be achieved with single-element additions.
2Reliability
If oxygen content is reduced to improve ductility, then ductility can be improved, but strength characteristics deteriorate
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the oxygen content parameter at 0.12-0.16%, which is a narrow and specific range. This precise parameter control allows the alloy to achieve optimal strength characteristics while maintaining excellent ductility, demonstrating that a specific, controlled amount of oxygen can simultaneously contribute to both strength and ductility rather than treating oxygen solely as a detrimental impurity.
3Ease of manufacture
If alloy composition ranges are broadened to simplify manufacturing, then ease of manufacture is improved, but strength-ductility combination deteriorates
Solution Approach 1:
The patent applies parameter changes by defining specific, optimized composition ranges for each element (Al: 5.3-5.7%, V: 4.8-5.2%, Mo: 4.6-5.3%, Cr: 2.0-2.5%, Fe: 0.7-0.9%, O: 0.12-0.16%). These precisely defined ranges provide sufficient manufacturing flexibility while ensuring consistent achievement of the target strength-ductility combination, resolving the contradiction between ease of manufacture and performance consistency.
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 alloy achieves tensile yield strength of at least 170 ksi, ultimate tensile strength of at least 180 ksi, modulus of elasticity of at least 16.0 Msi, elongation of at least 10%, and reduction of area of at least 25%, with a fatigue life of at least 200,000 cycles, effectively addressing the limitations of prior alloys in aviation applications.
Implementation Method 1
performing a solution heat treatment of the titanium alloy at temperatures below the beta transformation temperature
Implementation Method 2
performing precipitation hardening of the titanium alloy
Data Source
AI summary
A high strength near-beta titanium alloy including, in weight %, 5.3 to 5.7% aluminum, 4.8 to 5.2% vanadium, 0.7 to 0.9% iron, 4.6 to 5.3% molybdenum, 2.0 to 2.5% chromium, and 0.12 to 0.16% oxygen with balance titanium and incidental impurities is provided. An aviation system component comprising the high strength near-beta titanium alloy, and a method for the manufacture of a titanium alloy for use in high strength, deep hardenability, and excellent ductility applications are also provided.