TiAl Turbine Blade Forging with Refined Grain Orientation
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Solution Overview
Problem
The manufacturing of turbine engine blades using titanium aluminides (TiAl) alloys is hindered by low temperature brittleness, reduced resistance to cracking, poor castability, and the need for expensive hot isostatic pressing, which complicates shaping and results in significant material loss and high production costs.
Innovation Solution
A method involving spinning to refine the TiAl alloy structure, eliminating the need for hot isostatic compression, and using conventional forging to achieve parts close to final dimensions, with the spinning step combining compaction, sintering, and shaping to preserve a fine microstructure, thereby reducing material loss and production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If TiAl alloy is used to manufacture turbine blades, then density is reduced and mechanical strength is improved, but low temperature brittleness increases and resistance to cracking decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling processing parameters including temperature (600-950°C range), deformation rate, and forging pressure to achieve optimal microstructure in TiAl alloy blades, transforming the material's properties to overcome brittleness while maintaining weight advantages
Solution Approach 2:
The patent utilizes the composite nature of TiAl intermetallic alloys, leveraging their lamellar grain structure which combines titanium and aluminum in specific ratios to achieve both reduced density and improved mechanical strength, while controlling the composite microstructure through processing parameters
2Ease of manufacture
If TiAl alloy is shaped by conventional foundry, then casting is simplified, but castability deteriorates due to rapid solidification causing shrink marks and porosities
Solution Approach 1:
The patent applies preliminary action by performing hot isostatic pressing (HIP) treatment before final forging, which pre-densifies the casted TiAl alloy ingot to eliminate internal porosity and shrink marks, ensuring high manufacturing precision in subsequent shaping operations
Solution Approach 2:
The patent changes the temperature and pressure parameters during casting and subsequent HIP treatment to control the solidification rate and microstructure formation, preventing rapid solidification defects while maintaining ease of manufacture
3Ease of manufacture
If TiAl alloy is forged conventionally, then shaping is simplified, but the window of industrial forgeability narrows due to compromise between temperature and speed
Solution Approach 1:
The patent applies dynamics by implementing a dynamic forging process where temperature, pressure, and deformation rate are continuously adjusted during the forging operation, allowing the process to adapt to the material's changing properties and expand the effective forgeability window
Solution Approach 2:
The patent systematically varies processing parameters including heating temperature, forging pressure, and deformation speed to identify and exploit the optimal forgeability window for TiAl alloys, transforming the narrow parameter range into a controllable process
4Reliability
If hot isostatic pressing is used to treat TiAl alloy, then mechanical properties are improved, but production cost increases and grain enlargement occurs
Solution Approach 1:
The patent optimizes the HIP treatment parameters (temperature, pressure, time) to achieve the minimum effective treatment that improves mechanical properties without excessive grain growth or cost, and combines it with subsequent forging to refine the microstructure further
Solution Approach 2:
The patent combines HIP treatment with subsequent forging operations in an integrated process flow, where the HIP pre-treatment eliminates porosity and the forging refines the microstructure, achieving superior mechanical properties while distributing the complexity across multiple simpler steps
5Shape
If TiAl alloy is cast with thin thicknesses, then blade geometry is improved, but shrink marks and porosities increase due to rapid solidification
Solution Approach 1:
The patent applies preliminary hot isostatic pressing treatment to casted ingots with thin sections, which pre-densifies the material and eliminates porosity before forging, enabling the production of complex blade geometries with thin sections without sacrificing casting quality
Solution Approach 2:
The patent controls casting parameters including cooling rate, mold temperature, and alloy composition to slow down solidification in thin sections, preventing rapid solidification defects while achieving the required blade geometry
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 method enhances the mechanical properties of TiAl alloy blades by orienting lamellar grains perpendicular to the loading axis, increasing resistance to mechanical stresses, and reducing the need for extensive machining, resulting in blades with smaller grain size and improved durability.
Implementation Method 1
spinning to refine the TiAl alloy structure, eliminating the need for hot isostatic compression, and using conventional forging to achieve parts close to final dimensions, with the spinning step combining compaction, sintering, and shaping
Implementation Method 2
the spinning step combining compaction, sintering, and shaping to preserve a fine microstructure
Implementation Method 3
orienting lamellar grains perpendicular to the loading axis, increasing resistance to mechanical stresses
Implementation Method 4
by orienting the lamellae of the alloy in the direction perpendicular to the loading axis of the blade
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3
AI summary
The present invention relates to a method for manufacturing a titanium aluminide blade of a turbine engine, comprising steps of: (E1) production of a titanium aluminide ingot, (E2) extrusion of the ingot through an opening in a die having one main arm and at least one side arm, such as to obtain a extruded ingot having the shape of a bar with a cross-section having one main arm and at least one side arm substantially perpendicular to the main arm, (E3) transverse cutting of the extruded ingot such as to obtain sections of extruded ingot, (E4) forging of each section of extruded ingot such as to obtain a turbine engine blade.