Additive Manufactured HEA Member Cooling Rate Control
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Solution Overview
Problem
Existing high entropy alloy (HEA) members produced by additive manufacturing exhibit limitations in mechanical strength, ductility, and corrosion resistance, particularly in severe use environments.
Innovation Solution
A method involving additive manufacturing using an alloy powder composition of Co, Cr, Fe, Ni, Ti, and Mo, followed by a heat treatment at 1080° C. to 1180° C., and a forced cooling step at a rate of 110° C./min to 2400° C./min to suppress the deposition of hexagonal precipitates, thereby enhancing mechanical properties and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional heat treatment with air-cooling or water-cooling is applied after pseudo-solution heat treatment, then mechanical strength and ductility are improved, but corrosion resistance is insufficient for severe use environments
Solution Approach 1:
The invention changes the cooling rate parameter from conventional air-cooling or water-cooling to a controlled forced cooling rate of 110 to 2400° C./min. This parameter optimization suppresses the deposition of hexagonal precipitates in grain boundaries while maintaining mechanical strength and ductility improvements, thereby achieving enhanced corrosion resistance in severe environments
Solution Approach 2:
The invention utilizes phase transition control during the forced cooling process from holding temperature to 800° C. By controlling the cooling rate within the specified range, the phase transformation behavior is optimized to minimize harmful hexagonal precipitate formation while preserving the beneficial microstructure for both mechanical strength and corrosion resistance
2Strength
If rapid cooling is applied to improve mechanical strength and ductility, then tensile strength and elongation are enhanced, but hexagonal precipitates deposit in grain boundaries reducing corrosion resistance
Solution Approach 1:
The invention optimizes the cooling rate parameter to a specific range of 110 to 2400° C./min, which is faster than conventional cooling but controlled to avoid excessive precipitate deposition. This parameter refinement allows achieving high tensile strength and elongation while suppressing harmful hexagonal precipitate formation in grain boundaries
Solution Approach 2:
The invention applies dynamic control of the cooling process by specifying a cooling rate range rather than a fixed value. This dynamic approach allows the cooling speed to be adjusted within the optimal range to balance mechanical property enhancement with suppression of harmful precipitate deposition, achieving both high strength and good corrosion resistance
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
The method achieves improved mechanical strength, ductility, and corrosion resistance in HEA members, with tensile strength exceeding 1100 MPa, elongation at break of 10% or more, and a corrosion rate in 10% boiling sulfuric acid of 5 mm/year or less.
Implementation Method 1
a heat treatment step for raising a temperature of the products through heating and holding the products at a temperature between 1080° C. and 1180° C.
Implementation Method 2
a forced cooling step for cooling the products after the heat treatment in a temperature range from a holding temperature to 800° C. at a cooling rate between 110° C./min and 2400° C./min
Data Source
AI summary
Provided are: a method for producing an alloy member that is fabricated by additive manufacturing and has increased mechanical strength and ductility as well as higher corrosion resistance; and the alloy member produced from this method. The alloy member production method comprises: an additive manufacturing step for forming products by additive manufacturing using an alloy powder including each of Co, Cr, Fe, Ni, and Ti in the range of 5-35 atom % and Mo in the range of greater than 0 atom % and 8 atom % or less, the balance comprising unavoidable impurities; a heat treatment step for raising a temperature of the products through heating, and holding the products in the temperature range of 1080-1180° C.; and a forced cooling step for cooling the products after the heat treatment in the temperature range from the holding temperature to 800° C. at a cooling rate of 110-2400° C./min.