Layered Titanium Composition for Low-Cost Surface Ductility
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Solution Overview
Problem
The high production cost of titanium products is attributed to the discontinuous batch-type processes used in producing titanium sponge and ingots, leading to residual magnesium chloride (MgCl2) in the final product, which affects mechanical properties and requires high-purity titanium sponge, increasing costs. Additionally, the uneven melting of porous titanium sponges results in uneven surface layers during hot rolling, causing texture and mechanical property issues.
Innovation Solution
A titanium product with a structured composition and production method involving a surface layer and inner layer portion, where the Cl content and thickness are controlled to satisfy a specific ratio, allowing for hot and cold working without increasing production costs, thereby improving surface texture and ductility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If discontinuous batch-type processes are used to produce titanium sponge and ingots, then the production cost increases, but the mechanical properties are maintained
Solution Approach 1:
The titanium product is divided into two distinct layers: a surface layer portion with high purity (Cl ≤ 0.020 mass %) providing excellent mechanical properties, and an inner layer portion with lower purity (0.020 < Cl ≤ 0.60 mass %) that can tolerate higher chloride content. This segmentation allows different regions to serve different functions, enabling cost reduction in the inner layer while maintaining quality at the surface.
Solution Approach 2:
Different chloride content thresholds are applied to different regions of the titanium product. The surface layer requires strict chloride control (≤ 0.020 mass %) to ensure mechanical properties, while the inner layer allows higher chloride content (up to 0.60 mass %) to reduce production costs. This local quality approach optimizes both cost and performance.
2Reliability
If high-purity titanium sponge is used to reduce residual MgCl2, then the mechanical properties are improved, but the production cost increases
Solution Approach 1:
High-purity titanium sponge is used only for the surface layer portion where mechanical properties are critical (Cl ≤ 0.020 mass %), while lower-purity titanium sponge is used for the inner layer portion where chloride content can be higher (0.020 < Cl ≤ 0.60 mass %). This localized quality approach ensures mechanical properties where needed while reducing costs in non-critical regions.
Solution Approach 2:
The product structure is segmented into surface and inner layers with different purity requirements. The surface layer uses high-purity material for mechanical performance, while the inner layer uses lower-purity material for cost efficiency, resolving the contradiction between quality and cost.
3Quantity of substance
If electron beam melting is applied to remove MgCl2, then the purity is improved, but the production cost increases
Solution Approach 1:
Instead of applying electron beam melting to the entire titanium sponge to remove all MgCl2, the process applies partial purification only to the surface layer portion. The inner layer retains higher MgCl2 content, avoiding the excessive cost of complete purification while maintaining sufficient purity where it matters most for mechanical properties.
Solution Approach 2:
Purification efforts are concentrated locally in the surface layer portion where high purity is critical for mechanical properties, rather than uniformly purifying the entire product. This localized purification approach reduces production costs while maintaining necessary quality standards.
4Ease of manufacture
If porous titanium sponge is melted unevenly, then the production cost is reduced, but the surface texture becomes uneven
Solution Approach 1:
The melting process is segmented into two zones: a surface layer portion that is uniformly melted and solidified to create a smooth, even surface texture, and an inner layer portion that remains porous and unmelted to maintain cost efficiency. This segmentation resolves the contradiction between cost reduction and surface quality.
Solution Approach 2:
Uniform melting and solidification is applied locally only to the surface layer portion to ensure smooth surface texture, while the inner layer maintains its porous structure without melting. This localized treatment achieves surface quality without the excessive cost of complete melting.
5Manufacturing precision
If the thickness of dense coating portion is increased, then the surface texture is improved, but the production cost increases
Solution Approach 1:
The product structure is segmented into a surface layer portion with uniform thickness and smooth texture, and an inner layer portion with porous structure. This segmentation allows the surface layer to provide excellent surface texture without requiring excessive material thickness, thereby controlling production costs.
Solution Approach 2:
High-quality uniform material is provided locally in the surface layer portion where surface texture is critical, while the inner layer maintains lower quality porous structure for cost efficiency. This localized quality distribution achieves surface texture improvement without excessive cost increase.
Data Source
AI summary
A titanium product includes an inner layer portion and a surface layer portion joined to the inner layer portion. The surface layer portion has a composition consisting of, by mass %, O: 0.4% or less, Fe: 0.5% or less, Cl: 0.020% or less, the balance: Ti and impurities. The inner layer portion 3 has pores and a composition consisting of, by mass %, O: 0.4% or less, Fe: 0.5% or less, Cl: more than 0.020% and 0.60%, the balance: Ti and impurities. The area fraction of the pores in the inner layer portion in a cross-section perpendicular to the longitudinal direction of the titanium product is more than 0% and not more than 30%. The Cl content (ClI) of the inner layer portion, a thickness (tS) of the surface layer portion, and a thickness (tI) of the inner layer portion satisfy the expression [ClI≤0.03+0.02×tS/tI].