Alpha+gamma Titanium Aluminide Preform Stretch Forging
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Solution Overview
Problem
The existing methods for producing high-strength components from α+γ titanium aluminide alloys, such as those used in aircraft engines and gas turbines, face challenges due to the high forming resistance of TiAl alloys, requiring complex isothermal forging processes at high temperatures and large presses, which result in inefficient material usage and the formation of burrs.
Innovation Solution
A method involving partial stretch forging using a manipulator to incrementally shape the alloy, reducing the need for large presses and allowing forging in air, with tools made of ceramic or molybdenum, and subsequent isothermal forming in the β-phase range to achieve the desired geometry and microstructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If isothermal forging is used to produce preform from TiAl alloy blank, then the desired shape and microstructure are achieved, but extremely large press force of 400-500 tons is required
Solution Approach 1:
The patent divides the forming process into two distinct stages: (1) stretch forging to create a preform with approximate shape, and (2) isothermal forging to achieve final precision shape and microstructure. This segmentation allows the high-force isothermal forging to act only on a pre-shaped preform rather than a full-size blank, reducing the required press force from 400-500 tons to a manageable level while maintaining manufacturing precision.
Solution Approach 2:
The patent performs preliminary stretch forging to create a preform that approximates the final component shape before undergoing isothermal forging. This preliminary action reduces the volume and complexity of material that requires high-force isothermal deformation, thereby reducing the press force requirement while ensuring the final precision is achieved in the second stage.
2Manufacturing precision
If isothermal forging is used to produce preform, then the desired geometry is achieved, but the forming rate must be extremely slow
Solution Approach 1:
The patent segments the forming process into stretch forging (faster, lower precision) followed by isothermal forging (slower, high precision). By separating these operations, the slow forming rate is confined only to the critical final shaping stage, while the majority of material removal and rough shaping occurs faster in the first stage, improving overall productivity.
Solution Approach 2:
The patent applies partial action by performing stretch forging first to achieve approximate geometry, then applying the slow isothermal forging only to the extent necessary for final precision. This avoids subjecting the entire forming process to the slow rate, thereby improving overall productivity while maintaining geometric precision where required.
3Reliability
If large blanks are used to ensure sufficient volume for isothermal forging, then the forming can be completed, but burrs or sections occur on the sides of the preform that must be separated and discarded
Solution Approach 1:
The patent performs preliminary stretch forging to create a preform that closely approximates the final component shape and volume requirements. This preliminary action ensures that sufficient material is present for the subsequent isothermal forging without requiring excessive blank size, thereby minimizing burr formation and material waste during the final forming stage.
Solution Approach 2:
The patent applies local quality by using stretch forging to locally shape specific regions of the blank into a preform configuration that optimizes material distribution. This local shaping ensures adequate material volume in critical areas for isothermal forging while avoiding excess material in non-critical areas, reducing burr formation and subsequent material waste.
4Ease of manufacture
If molybdenum tools are used for isothermal forging, then the forming can be performed, but the process must be carried out in inert atmosphere or vacuum
Solution Approach 1:
The patent employs stretch forging tools that can operate in air atmosphere, eliminating the need for expensive molybdenum tools and complex inert atmosphere or vacuum systems. While stretch forging tools may have shorter service life under atmospheric conditions, this approach significantly reduces device complexity and operational costs, making the process more economically viable.
Solution Approach 2:
The patent extracts the requirement for inert atmosphere from the overall process by separating the operations: stretch forging is performed in air using simple tools, while only the critical isothermal forging stage would require controlled atmosphere. This extraction eliminates the need for continuous atmosphere control during the majority of the forming process, reducing device 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
This approach reduces the required forging force significantly, eliminates the need for protective atmospheres in some cases, and allows for the use of smaller blanks, resulting in a more efficient and burr-free preform production process with improved mechanical properties.
Implementation Method 1
the blank is only partially formed by stretch forging using a stretch forging tool. The invention envisages producing the preform by stretch forging a blank. In stretch forging, the desired shape is incrementally created by multiple impacts on the workpiece
Implementation Method 2
The blank is expediently kept at a temperature in the range of 1070-1300° C. during stretch forging. The blank and the stretch forging tool itself are preferably heated during stretch forging by means of a radiant heating device
Implementation Method 3
the blank being moved between two strokes by a defined path in the longitudinal direction of the workpiece by means of the program-controlled manipulator. The workpiece is moved at least once in one direction through the stretch forging tool by means of the manipulator
Implementation Method 4
In a second, also isothermal secondary forming process with simultaneous dynamic recrystallization in the α+y or α phase range in a temperature range of 1000 - 1340 °C, the component is formed to the specified shape by forging
Implementation Method 5
the component is used to adjust the microstructure in the α phase range solution annealed and then rapidly cooled
Implementation Method 6
the component is used to adjust the microstructure in the α phase range solution annealed and then rapidly cooled
Data Source
AI summary
Method for producing a preform from an α+γ-titanium aluminide alloy for producing a high-strength component for piston engines and gas turbines, in particular aircraft engines, by forging a blank, wherein the blank (1) held in a manipulator (2) and moved over the manipulator (2) is only partially reshaped by stretch forging using a stretch forging tool (5).