Annular Body Forging With Controlled Strain for Uniform Grain Structure
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Solution Overview
Problem
The production of large annular formed bodies for turbine disks faces challenges in achieving uniform mechanical strengths and structure uniformity due to limitations in existing forging methods, which are costly and difficult to scale, leading to issues with anisotropy and grain size uniformity.
Innovation Solution
A method involving melting and casting followed by controlled hot forging and ring rolling, where strain rates are maintained at 0.5 s^-1 or less, with specific strain values and ratios in the circumferential and height directions, to produce annular formed bodies with refined crystal structures and uniform grain sizes, using Ni-based, Co-based, or Fe-based alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a large hydraulic-control forging press is used to produce large annular formed bodies, then the mechanical strength and structure uniformity can be improved, but the equipment cost increases significantly and the supply capacity is limited
Solution Approach 1:
The patent combines ring rolling and forging processes into a single integrated device that performs both operations simultaneously. The ring rolling device and forging device are merged into one system, allowing the workpiece to undergo both processes without removal, thereby achieving the structural uniformity of forging with reduced equipment cost and complexity.
Solution Approach 2:
The integrated device performs multiple functions: ring rolling to shape the annular workpiece and forging to refine its internal structure. This multi-functional approach eliminates the need for separate large-capacity forging presses, reducing equipment investment while maintaining product quality.
2Ease of manufacture
If ring rolling is used to form large annular formed bodies, then the equipment cost is reduced and production flexibility is improved, but the anisotropy of mechanical characteristics increases
Solution Approach 1:
The ring rolling process is performed first to create the annular shape and preliminary structure, preparing the workpiece for the subsequent forging process. This preliminary shaping enables the integrated device to then apply forging pressure that refines the crystal structure and reduces anisotropy, achieving uniform mechanical characteristics.
Solution Approach 2:
The patent controls the forging pressure and deformation parameters in the integrated device to optimize the refinement of crystal grains. By adjusting these parameters, the forging process effectively reduces the anisotropy introduced during ring rolling, achieving uniform mechanical properties throughout the annular formed body.
3Adaptability or versatility
If a combination of forging press and ring rolling is used, then the production flexibility is improved, but the production process becomes complex and production costs increase
Solution Approach 1:
The patent merges ring rolling and forging operations into a single integrated device, eliminating the need for separate equipment and multiple handling steps. The workpiece remains in one position while undergoing both processes, simplifying the production flow and reducing operational complexity despite maintaining production flexibility.
4Stability of the object's composition
If hot forging is carried out multiple times with controlled strain ratios, then the crystal structure uniformity is improved, but the production time and process complexity increase
Solution Approach 1:
The integrated device performs ring rolling and forging in continuous sequence without interruption or removal of the workpiece. This continuous process achieves the same crystal structure uniformity as multiple separate forging operations but in a single uninterrupted workflow, significantly reducing production time.
Solution Approach 2:
The ring rolling process prepares the workpiece by creating the annular shape and initial structure, enabling the subsequent forging process to focus specifically on refining the crystal structure. This preliminary preparation allows the forging step to achieve uniform crystal structure more efficiently than if starting from a raw billet.
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 ensures high mechanical strengths and structural uniformity of annular formed bodies, stabilizing production while reducing costs, by controlling strain rates and ratios to prevent heat build-up and enhance plastic flow symmetry.
Implementation Method 1
strain is imparted to an annular formed body and crystal grains of the material are refined by forging
Implementation Method 2
a melting and casting step of producing an alloy piece by melting and casting
Data Source
Figure 1~2
Figure 3
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AI summary
The present invention is directed to a method for manufacturing an annular formed body comprising a forging step of forging an alloy piece to provide a forged body having a disc shape, and a ring rolling step of ring-rolling an annular intermediate body prepared by forming a through-hole in the forged body to provide an annular formed body, characterized in that the forging step comprises at least two hot forging steps, each of the hot forging steps being carried out under the conditions that a strain rate is at most 0.5 s-1, an absolute value εθ1 of strain to the forged body in its circumferential direction is at least 0.3, an absolute value εh of strain to the forged body in its height direction is at least 0.3, and a ratio εh/εθ1 between the absolute values of strain is within a range from 0.4 to 2.5.