Carbonitrided Metal Core for Hot-Forming Titanium Alloy Parts
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Solution Overview
Problem
The existing manufacturing processes for titanium-based alloy metal components, such as leading edge shields for turbine blades, face challenges including high costs, tool wear, and difficulty in achieving complex shapes due to the use of titanium alloys, which require expensive and inefficient methods like plasma deposition of yttrium oxide layers and lengthy carbonitriding treatments.
Innovation Solution
A metal core comprising a nickel- or cobalt-based alloy with chromium, molybdenum, and titanium, coated with a steel layer enriched with metal carbonitride, allowing for hot-forming of titanium-based alloys into complex geometries with high fatigue strength and enabling easy separation and reuse of the core without contamination, using a process that includes carbonitriding and regeneration of the steel coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma deposition of yttrium oxide layer is used as diffusion barrier, then contamination of titanium alloy is prevented, but manufacturing cost increases and layer uniformity is difficult to achieve on complex shapes
Solution Approach 1:
The patent changes the material parameter of the diffusion barrier from yttrium oxide to a steel coating with specific composition (carbon: 0.7-1.5%, chromium: 1.5-3%, molybdenum: 0.5-1%, titanium: 0.5-1%). This material substitution enables the barrier to be applied through carbonitriding treatment instead of expensive plasma deposition, reducing manufacturing cost while maintaining effectiveness.
Solution Approach 2:
The steel coating acts as an intermediary diffusion barrier between the nickel- or cobalt-based alloy core and the titanium-based alloy. The carbonitride-enriched layer formed through carbonitriding creates a stable intermediate zone that prevents direct contact and contamination between the core material and titanium alloy, while being easier and cheaper to apply than plasma-deposited yttrium oxide.
2Reliability
If carbonitriding treatment is applied to nickel- or cobalt-based alloy core, then diffusion barrier is formed, but treatment time exceeds 100 hours which is very long
Solution Approach 1:
The patent optimizes the carbonitriding process parameters including temperature (900-1100°C), time (2-10 hours), and atmosphere composition to achieve effective carbonitride enrichment in significantly reduced time compared to conventional treatments exceeding 100 hours. The specific steel coating composition also facilitates faster carbonitride formation.
Solution Approach 2:
The steel coating is designed as a composite material with specific alloying elements (carbon, chromium, molybdenum, titanium) that enhance the kinetics of carbonitride formation. This composite composition allows the diffusion barrier to form rapidly during carbonitriding while maintaining the required stability and effectiveness.
3Strength
If titanium alloy is used for leading edge shields, then high resistance and mechanical qualities are achieved, but manufacturing cost increases due to tool wear and number of steps
Solution Approach 1:
The patent replaces complex mechanical forging operations with a hot-forming process. The titanium alloy is heated to austenitic temperature range and formed around a core, then cooled to produce the final shape. This thermal-mechanical process substitutes for multiple costly mechanical steps including bending, tamping, extrusion, and twisting, reducing tool wear and manufacturing complexity while maintaining the required mechanical properties.
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
This solution reduces manufacturing costs and tool wear by enabling the production of complex titanium-based alloy components with high fatigue strength, allowing for multiple uses of the metal core and minimizing surface machining, while maintaining the integrity of the titanium-based alloy through a stable and inert diffusion barrier.
Implementation Method 1
a steel coating having an outer surface intended to come into contact with the metal component, the steel coating having a layer of metal carbonitride-enriched material
Implementation Method 2
the steel coating having a layer of metal carbonitride-enriched material... forming a diffusion barrier between the metal alloy of the core and the titanium-based alloy
Data Source
AI summary
A metal core for hot-forming a titanium-based alloy metal component is disclosed. The metal core has on an outer surface, intended to come into contact with the metal component, a layer of metal carbonitride-enriched material. The metal core comprises a nickel- or cobalt-based alloy. The metal core comprising a steel coating having an outer surface intended to come into contact with the metal component, the steel coating having a layer of metal carbonitride-enriched material. Processes for manufacturing and regenerating the metal core and a process for hot-forming a metal component using the metal core are also disclosed.