Alpha/Beta Titanium Fastener Strength via Composition
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Solution Overview
Problem
Current titanium alloy fasteners used in aerospace applications, such as Ti-6Al-4V, do not meet the high strength requirements for certain mechanical demands, leading to the use of heavier iron and nickel-based alloys, which increases weight and costs. There is a need for lightweight alpha/beta titanium alloy fasteners with higher strength to achieve weight reduction and fuel savings in aircraft.
Innovation Solution
Development of an alpha/beta titanium alloy with a specific composition (3.9-4.5% aluminum, 2.2-3.0% vanadium, 1.2-1.8% iron, 0.24-0.3% oxygen, up to 0.08% carbon, up to 0.05% nitrogen, and incidental impurities like tin, zirconium, molybdenum, chromium, etc.) that is hot rolled, annealed, solution treated, and aged to achieve ultimate tensile strengths of at least 170 ksi (1,172 MPa) and double shear strengths of at least 103 ksi (710.2 MPa).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If Ti-6Al-4V titanium alloy fasteners are used, then weight is reduced compared to steel alloys, but strength is insufficient for high mechanical demand applications
Solution Approach 1:
The patent modifies the chemical composition parameters of the Ti-6Al-4V alloy by adding specific amounts of iron (0.5-2.0 wt%), oxygen (0.20-0.35 wt%), carbon (0.05-0.10 wt%), and nitrogen (0.03-0.08 wt%), while maintaining aluminum (3.5-5.0 wt%) and vanadium (2.0-3.5 wt%) within specified ranges. These parameter changes transform the alloy's mechanical properties to achieve both high strength and weight reduction
Solution Approach 2:
The patent creates a composite alloy system by combining multiple elements (Ti, Al, V, Fe, O, C, N) in specific proportions to form a new material with superior properties. The resulting alloy integrates the lightweight characteristic of titanium with enhanced strength from alloying elements, resolving the contradiction between weight and strength
2Strength
If iron and nickel based superalloy fasteners are used to increase strength, then mechanical strength is improved, but weight increases and fuel efficiency decreases
Solution Approach 1:
The patent changes the base material from heavy iron/nickel superalloys to lightweight titanium alloy by modifying the titanium alloy's composition parameters. The controlled addition of Fe, O, C, and N to Ti-6Al-4V achieves strength levels comparable to superalloys while maintaining titanium's inherent lightweight advantage, thus resolving the weight-strength trade-off
3Strength
If beta-titanium alloys are used to increase strength, then ultimate tensile strength is improved, but density increases and cost increases
Solution Approach 1:
The patent applies local quality by selectively adding specific alloying elements (Fe, O, C, N) in controlled amounts to the Ti-6Al-4V matrix, creating localized strengthening without uniformly increasing the overall density. This targeted approach enhances strength while maintaining the lightweight characteristic of alpha/beta titanium alloys, unlike bulk beta-titanium alloys
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 new alpha/beta titanium alloy fasteners exhibit significantly higher strength and reduced variability in mechanical properties, enabling their use in smaller dimensions to replace Ti-6Al-4V fasteners, providing weight savings and potentially replacing steel alloy fasteners, thus reducing aircraft weight and fuel consumption.
Implementation Method 1
an article of manufacture selected from a titanium alloy fastener and a titanium alloy fastener stock includes an alpha/beta titanium alloy
Implementation Method 2
an article of manufacture selected from a titanium alloy fastener and a titanium alloy fastener stock includes an alpha/beta titanium alloy
Implementation Method 3
an article of manufacture selected from a titanium alloy fastener and a titanium alloy fastener stock includes an alpha/beta titanium alloy
Implementation Method 4
the alpha/beta titanium alloy fastener or fastener stock exhibits an ultimate tensile strength of at least 170 ksi (1,172 MPa)
Data Source
AI summary
An article of manufacture selected from a titanium alloy fastener and a titanium alloy fastener stock including an alpha/beta titanium alloy comprising, in percent by weight: 3.9 to 4.5 aluminum; 2.2 to 3.0 vanadium; 1.2 to 1.8 iron; 0.24 to 0.3 oxygen; up to 0.08 carbon; up to 0.05 nitrogen; titanium; and up to a total of 0.3 of other elements. In certain embodiments, article of manufacture has an ultimate tensile strength of at least 170 ksi (1,172 MPa) and a double shear strength of at least 103 ksi (710.2 MPa). A method of manufacturing a titanium alloy fastener and a titanium alloy fastener stock comprising the alpha/beta alloy is disclosed.