Titanium Alloy Composition for Scrap Utilization
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Solution Overview
Problem
The high material and processing costs of titanium alloys, particularly due to the need for tight control of minor elements like iron and oxygen, and the costly machining processes, limit their application in industries such as aerospace, defense, and energy, where low-weight, corrosion-resistant structures are required.
Innovation Solution
A titanium alloy composition with specific ranges of aluminum, vanadium, molybdenum, chromium, iron, oxygen, and incidental elements, processed through near-net shape casting and cooling, which avoids the need for hot working and allows for the formation of a basketweave microstructure, reducing material waste and processing costs while maintaining high strength and ductility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If tight control of minor elements like iron and oxygen is implemented, then mechanical property uniformity is improved, but material cost increases
Solution Approach 1:
The invention changes the compositional parameters by allowing broader ranges of minor elements (Fe: 0.05-1.00%, O: 0.03-0.35%) compared to conventional ELI grades, while compensating with specific alloying elements (Mo: 0.50-4.50%, Cr: 1.00-2.50%, Sn: 0.00-1.50%) to maintain mechanical property uniformity without requiring tight control
Solution Approach 2:
The invention uses cheaper raw materials by tolerating higher levels of incidental elements and impurities that would otherwise require expensive purification, accepting that some minor elements will be present but designing the alloy composition to remain effective within these broader tolerances
2Strength
If conventional wrought processing is used, then mechanical properties are improved, but processing cost and material waste increase
Solution Approach 1:
The invention utilizes phase transition during controlled cooling from the beta phase to alpha phase transformation, creating a basketweave microstructure through diffusion-controlled transformation that achieves superior mechanical properties without requiring subsequent hot working or machining
Solution Approach 2:
The invention replaces the mechanical working and machining processes with a metallurgical solution - controlling the phase transformation during cooling to inherently produce the desired microstructure and mechanical properties, eliminating the need for costly mechanical intervention
3Strength
If hot working is performed to achieve good strength and ductility, then mechanical properties are improved, but processing complexity and cost increase
Solution Approach 1:
The invention performs preliminary action by controlling the solidification and cooling process to pre-establish the desired basketweave microstructure and mechanical properties, eliminating the need for subsequent hot working operations that would add processing complexity
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 a combination of high strength and toughness at a lower cost by using low-cost raw materials and tolerating incidental elements, enabling the use of scrap titanium and reducing machining costs, with a microstructure that is robust and industrially feasible.
Implementation Method 1
cooling the alloy with a gas pressurized to about 2 atm... the alpha lath basketweave morphology of the intragrain microstructure is achieved upon cooling from above the beta transus temperature
Data Source
AI summary
Provided herein are titanium alloys that can achieve a combination of high strength and high toughness or elongation, and a method to produce the alloys. By tolerating iron, oxygen, and other incidental elements and impurities, the alloys enable the use of lower quality scrap as raw materials. The alloys are castable and can form α-phase laths in a basketweave morphology by a commercially feasible heat treatment that does not require hot-working or rapid cooling rates. The alloys comprise, by weight, about 3.0% to about 6.0% aluminum, 0% to about 1.5% tin, about 2.0% to about 4.0% vanadium, about 0.5% to about 4.5% molybdenum, about 1.0% to about 2.5% chromium, about 0.20% to about 0.55% iron, 0% to about 0.35% oxygen, 0% to about 0.007% boron, and 0% to about 0.60% other incidental elements and impurities, the balance of weight percent comprising titanium.