Titanium Composite Layering for Low-Cost Corrosion-Resistant Hot Rolling
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Solution Overview
Problem
The high production cost and reduced formability of titanium alloys due to the use of scarce and expensive platinum group elements, along with the adverse effects on workability and formability from added elements like Al, Fe, and Nb, make it challenging to produce titanium materials with improved corrosion resistance, oxidation resistance, fatigue resistance, and hydrogen embrittlement resistance at a lower cost.
Innovation Solution
A titanium composite material is developed with an inner layer of commercially pure titanium or titanium alloy and an outer layer with a different chemical composition, including platinum group elements, rare earth elements, Co, and Ni, to enhance corrosion and oxidation resistance, while maintaining formability and reducing the overall cost by minimizing the usage of expensive alloying elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If platinum group elements (Ru, Rh, Pd, Os, Ir, Pt) are added to titanium to improve corrosion resistance, then corrosion resistance is improved, but production cost increases significantly
Solution Approach 1:
The patent applies local quality by creating a surface layer with different composition than the bulk material. The surface layer contains elevated concentrations of corrosion-resistant elements (Pd: 0.01-0.5 mass%, Ru: 0.01-0.5 mass%, or other platinum group elements) only where corrosion resistance is needed, while the base titanium material maintains lower alloy content for cost efficiency and good workability.
Solution Approach 2:
The patent creates a composite structure with a base titanium material and a surface layer enriched with corrosion-resistant alloying elements. This composite approach combines the low cost and good formability of pure titanium with the superior corrosion resistance of platinum group element-containing alloys, resolving the contradiction between cost and corrosion resistance.
2Strength
If Al, Fe, or Nb are added to improve high temperature strength and oxidation resistance, then high temperature properties are improved, but workability and formability deteriorate
Solution Approach 1:
The patent confines the alloying elements (Al: 0.1-5.0 mass%, Fe: 0.1-5.0 mass%, Nb: 0.1-5.0 mass%) to the surface layer with thickness 1-50 μm, where high temperature oxidation resistance is required. The bulk titanium material remains relatively pure, maintaining excellent workability and formability during manufacturing processes.
Solution Approach 2:
The patent applies partial action by providing high temperature resistance only in the surface layer where it is most needed for oxidation protection, rather than alloying the entire material. This allows the bulk material to retain good workability while the surface provides the necessary high temperature properties.
3Reliability
If alloying elements are added throughout the material to improve corrosion resistance, then corrosion resistance is improved, but production cost increases
Solution Approach 1:
The patent concentrates corrosion-resistant alloying elements (platinum group elements, Pd, Ru, Ni, Co, Mn) exclusively in the surface layer (1-50 μm thickness), where corrosion protection is most critical. The base titanium material maintains low alloy content, significantly reducing material cost while providing sufficient corrosion resistance through the protected surface layer.
Solution Approach 2:
The patent provides corrosion resistance partially through a thin surface layer rather than throughout the entire material thickness. This partial approach achieves adequate corrosion protection for most applications while dramatically reducing the amount of expensive alloying elements required, thus lowering production cost.
Data Source
AI summary
A titanium composite material 1 is provided that includes: an inner layer 5 consisting of a commercially pure titanium or a titanium alloy; an outer layer 3 formed on at least one surface of the inner layer 5 and having a chemical composition that is different from a chemical composition of the inner layer 5; and an intermediate layer formed between the inner layer 5 and the outer layer 3 and having a chemical composition that is different from the chemical composition of the inner layer 5. The thickness of the outer layer 3 is 2 μm or more, and occupies no more than 40% of the overall thickness per side. The thickness of the intermediate layer is 0.5 μm or more. Despite being inexpensive, this titanium composite material has desired characteristics.