Ni-based Superalloy Hot Working via Controlled γ' Phase Coarsening
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Solution Overview
Problem
Ni-based superalloys with a large γ' phase exhibit high high-temperature strength but are difficult to hot work stably due to increased deformation resistance and reduced hot ductility, especially at high strain rates, limiting their application in aircraft engines and gas turbines.
Innovation Solution
A method involving a specific composition and processing steps, including preliminary heating and hot working within a controlled temperature range to coarsen the γ' phase, allowing hot working at high strain rates while maintaining high strength and ductility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the amount of γ' phase is increased to improve high-temperature strength, then high-temperature strength is improved, but deformation resistance is increased and hot ductility is decreased
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition parameters (Al: 1.0-4.0%, Ti: 3.0-7.0%, Cr: 12-18%, Co: 12-30%, Mo: 1.5-5.5%, W: 0.5-2.5%, Ta: 0-3%, Nb: 0-3%) and hot working parameters (temperature: 950-1150°C, strain rate: 0.01-10/s) to optimize the balance between γ' phase amount and hot workability. This resolves the contradiction by finding the optimal parameter range where sufficient strengthening is achieved while maintaining manufacturability
Solution Approach 2:
The patent applies dynamics by controlling the strain rate (0.01-10/s) during hot working to dynamically adjust the deformation behavior. By optimizing the strain rate within this range, the patent achieves both high strength through sufficient γ' phase and adequate hot ductility, resolving the static contradiction between strength and workability
2Productivity
If high-speed hot working machines are used to improve productivity, then productivity is improved, but strain rate is increased which causes deformation resistance to increase and hot ductility to decrease
Solution Approach 1:
The patent applies parameter changes by optimizing the strain rate parameter within the range of 0.01-10/s, which covers both traditional low-speed working and high-speed working conditions. This allows the use of high-speed hot working machines while maintaining adequate hot ductility through precise parameter control, resolving the contradiction between productivity and manufacturability
Solution Approach 2:
The patent applies dynamics by introducing strain rate as a dynamic control parameter. The optimized strain rate range (0.01-10/s) enables dynamic adjustment between slow and fast working modes, allowing high-speed machines to be used effectively while maintaining material ductility through appropriate parameter selection
3Strength
If alloy elements such as Al and Ti are increased to increase γ' phase amount, then high-temperature strength is improved, but additive amount is limited due to increased deformation resistance
Solution Approach 1:
The patent applies parameter changes by optimizing the composition parameters within specific ranges: Al (1.0-4.0%), Ti (3.0-7.0%), Cr (12-18%), Co (12-30%), Mo (1.5-5.5%), W (0.5-2.5%), Ta (0-3%), and Nb (0-3%). These optimized parameter ranges achieve sufficient γ' phase formation for high-temperature strength while avoiding excessive deformation resistance, resolving the contradiction between strength improvement and additive limitation
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
Enables stable hot working of high-strength Ni-based superalloys with a large γ' phase at high strain rates, improving yield and reducing crack susceptibility, thus facilitating the production of complex shapes like long shafts and ring disks.
Implementation Method 1
A Ni-based superalloy which includes many alloy elements such as Al and Ti and is a γ' (gamma prime) phase-precipitation strengthened type
Implementation Method 2
hot working is further performed on a cast structure in a state where an alloy is melted and solidified, and thus recrystallization is accelerated
Data Source
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AI summary
A method of producing a Ni-based superalloy which has good hot workability at even a high strain rate is provided. The method is a method of producing a Ni-based superalloy, including: using a hot working material which has a composition consisting of, in mass%, 0.001 to 0.050% of C, 1.0% to 4.0% of Al, 3.0% to 7.0% of Ti, 12% to 18% of Cr, 12% to 30% of Co, 1.5% to 5.5% of Mo, 0.5% to 2.5% of W, 0.001% to 0.050% of B, 0.001% to 0.100% of Zr, 0% to 0.01% of Mg, 0% to 5% of Fe, 0% to 3% of Ta, 0% to 3% of Nb, and the remainder of Ni and inevitable impurities, and in which a solvus temperature of a γ' phase is equal to or higher than 1050°C, a preliminary heating step of performing heating in a temperature range that is 980°C to 1050°C and has an upper limit set to be -30°C from the solvus temperature of the γ' phase, for 10 hours or longer; and a hot working step of performing hot working on the hot working material after the preliminary heating step, at a working speed having a strain rate of 2.0/second or more in a temperature range that is 980°C to 1050°C and has an upper limit set to be -30°C from the solvus temperature of the γ' phase.