Titanium Alloy Impact Resistance via Phase Control
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Solution Overview
Problem
Conventional titanium alloys, such as Ti-6Al-4V, exhibit suboptimal performance and high manufacturing costs when used in applications requiring resistance to impact, explosive blast, and shock loading, with inadequate energy absorption and processing challenges.
Innovation Solution
Development of titanium alloys with specific compositions including aluminum, vanadium, silicon, iron, oxygen, and carbon, processed through beta and alpha forging, heat treatment, and remelting to achieve enhanced mechanical properties and machinability, offering improved ductility, ballistic impact resistance, and energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Ti-6Al-4V alloy is used for containment casings, then the alloy provides basic structural functionality, but the containment performance is less than desired and manufacturing cost is relatively high
Solution Approach 1:
The patent modifies the alloy composition parameters by adjusting aluminum content to 4-7 wt%, vanadium to 3-5 wt%, and adding silicon (0.1-0.5 wt%) and iron (0.05-0.5 wt%), while controlling oxygen (0.1-0.25 wt%) and carbon (up to 0.2 wt%). These parameter changes optimize both containment performance and manufacturing characteristics, reducing cost while improving reliability.
2Strength
If titanium alloy is designed for high strength and ductility, then mechanical properties improve, but energy absorption under impact loading may be compromised
Solution Approach 1:
The patent utilizes phase transition mechanisms by controlling the microstructure to contain both alpha and beta phases. The beta phase (30-60% volume fraction) provides ductility and energy absorption through martensitic transformation during impact, while the alpha phase contributes to strength. This phase combination resolves the contradiction between strength and energy absorption.
Solution Approach 2:
The alloy creates a composite microstructure with alpha and beta phases distributed throughout the material. This internal composite structure allows different phases to contribute different properties: alpha phase for strength and beta phase for ductility and energy absorption, simultaneously achieving both objectives.
3Reliability
If titanium alloy composition is optimized for ballistic impact resistance, then V50 ballistic limit improves, but ductility may be reduced
Solution Approach 1:
The patent optimizes composition parameters within specific ranges: aluminum (4-7 wt%) for strength, vanadium (3-5 wt%) for beta stabilization and toughness, silicon (0.1-0.5 wt%) for grain refinement, and controlled oxygen (0.1-0.25 wt%) for ductility. These parameter changes achieve both ballistic resistance and ductility simultaneously.
Solution Approach 2:
The patent creates local quality variations in the microstructure by controlling phase distribution and grain size. The alpha phase provides local strength for ballistic resistance while the beta phase provides local ductility, allowing the material to exhibit both properties at the microstructural level.
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 titanium alloys demonstrate up to 70% improvement in ductility, 16% increase in ballistic impact resistance, and 50% more energy absorption compared to conventional Ti-6Al-4V alloys, while reducing manufacturing costs and processing complexity.
Implementation Method 1
melting the blend in either a plasma or electron beam cold hearth furnace
Implementation Method 2
melting the blend in either a plasma or electron beam cold hearth furnace
Implementation Method 3
the ingot, which may be solid or hollow, that is formed during cold hearth melting may be remelted using vacuum arc remelting
Implementation Method 4
heat treating the processed part at a temperature between about 25° F. (14° C.) and about 200° F. (110° C.) below the beta transus
Implementation Method 5
annealing the processed and heat treated part at a temperature between about 750° F. (400° C.) and about 1,200° F. (649° C.)
Data Source
AI summary
Titanium alloys formed into a part or component used in applications where a key design criterion is the energy absorbed during deformation of the part when exposed to impact, explosive blast, and/or other forms of shock loading is described. The titanium alloys generally comprise a titanium base with added amounts of aluminum, an isomorphous beta stabilizing element such as vanadium, a eutectoid beta stabilizing element such as silicon and iron, and incidental impurities. The titanium alloys exhibit up to 70% or more improvement in ductility and up to a 16% improvement in ballistic impact resistance over a Ti-6Al-4V alloy, as well as absorbing up to 50% more energy than the Ti-6Al-4V alloy in Charpy impact tests. A method of forming a part that incorporates the titanium alloys and uses a combination of recycled materials and new materials is also described.