Titanium Alloy Forging Sequence for Uniform Turbine Rotor Grain
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Solution Overview
Problem
The existing forging processes for titanium alloy parts, particularly in turbomachines, often result in heterogeneous microstructures with large grains, which can compromise the mechanical properties of the final product due to inadequate deformation rates during the forging process, especially in large and thick rotating parts.
Innovation Solution
A modified forging process that includes at least one blank forging step with a local deformation rate greater than 0.2, followed by a final forging stage at a temperature above the beta transus temperature, ensuring a minimum local deformation rate of 0.2-0.4 at any point of the billet, to achieve a homogeneous and fine microstructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional forging processes are used for large and thick rotating parts, then the forging operation can be completed with standard procedures, but the microstructure becomes heterogeneous with large grains due to inadequate deformation rates
Solution Approach 1:
The forging process is divided into multiple stages: a first blank forging stage at temperature T1 below the beta transus temperature Tβ, followed by a second blank forging stage at temperature T2 above Tβ. Each stage applies deformation with a rate greater than 0.2, allowing progressive microstructure refinement without requiring excessive complexity in any single operation.
Solution Approach 2:
The invention changes the temperature parameter between forging stages (below Tβ then above Tβ) and controls the deformation rate parameter (greater than 0.2) to achieve microstructure refinement. This parameter control allows obtaining a homogeneous fine microstructure with grain size of 50 to 100 μm without overly complicating the forging process.
2Manufacturing precision
If the deformation rate during blank forging is increased to refine microstructure, then grain size is reduced to 50-100 μm, but the forging process requires more complex control of deformation rates
Solution Approach 1:
The invention specifies a deformation rate parameter greater than 0.2 during blank forging operations. This quantitative parameter control enables achieving a grain size of 50 to 100 μm while maintaining relatively simple forging operations, as the deformation rate threshold provides a clear operational guideline.
Solution Approach 2:
The blank forging stage is performed as a preliminary operation before final forging, during which the deformation rate is controlled to refine the microstructure. This preliminary action prepares the material with a fine homogeneous microstructure that simplifies subsequent final forging operations.
3Manufacturing precision
If multiple blank forging steps are performed to ensure homogeneous microstructure, then grain refinement is achieved, but the manufacturing time and process duration increase
Solution Approach 1:
The forging process is segmented into a blank forging stage followed by a final forging stage, with each stage performing a specific function. The blank forging stage refines the microstructure with deformation rate > 0.2, while the final forging stage completes the shaping, allowing efficient progression through distinct operational phases.
Solution Approach 2:
Microstructure refinement is performed as a preliminary action during the blank forging stage before the final forging operation. This ensures that the material is properly prepared with a homogeneous fine microstructure early in the process, preventing the need for additional corrective operations later and maintaining productivity.
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 process effectively refines the microstructure by recrystallizing large grains into smaller grains of 50 to 100 μm, enhancing the mechanical properties of the forged parts and avoiding the complexity of modifying the final forging step temperatures.
Implementation Method 1
This process effectively refines the microstructure by recrystallizing large grains into smaller grains of 50 to 100 μm
Implementation Method 2
a stage of final forging of said blank is carried out, in which said blank is heated to a temperature T2 greater than the beta transus temperature Tβ before carrying out the actual forging operation
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a method for forging a thermomechanical part and comprises the following steps: - providing a billet produced in a titanium alloy having a beta transus temperature Tb; - carrying out at least one step of forging a blank of said billet at a temperature T1 lower than the beta transus temperature Tb frombefore carrying out the forging operation whereby a blank is completed; carrying out a step of final forging said blank at a temperature T2 greater than the beta transus temperature Tb frombefore carrying out the forging operation whereby a blank is completed. Said forging operation from the blank-forging step characteristically carries out, on every point of said billet, a deformation greater than a minimum deformation rate. The invention is useful for a rotating part of a turbine engine.