High-Entropy Alloy Cryogenic Rolling for Hydrogen Embrittlement Resistance
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Solution Overview
Problem
High-strength metal materials with high hydrogen embrittlement resistance are challenging to produce using conventional methods, as severe plastic deformation techniques are limited in size and shape and reduce production efficiency, and materials with strengths above 1 GPa exhibit reduced hydrogen delayed fracture resistance.
Innovation Solution
A method involving annealing and homogenizing an initial alloy containing Co, Cr, Fe, Mn, and Ni, followed by cryogenic temperature rolling with a multi-pass caliber roller to form intersecting twins and secondary fine twins, enhancing grain refinement and hydrogen embrittlement resistance without severe plastic deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If severe plastic deformation techniques are used to increase strength, then strength is improved, but production efficiency is reduced and hydrogen delayed fracture resistance is significantly reduced
Solution Approach 1:
The invention changes the temperature parameter to cryogenic conditions (-196°C) during rolling, which fundamentally alters the deformation mechanism. This enables grain refinement and strength enhancement without requiring severe plastic deformation, thereby maintaining production efficiency while achieving ultrahigh strength and improved hydrogen delayed fracture resistance
Solution Approach 2:
The invention performs preliminary annealing treatment before cryogenic rolling to optimize the microstructure. This preliminary action prepares the material for subsequent cryogenic deformation, enabling effective grain refinement at lower strain levels and avoiding the need for severe plastic deformation, thus preserving both productivity and hydrogen embrittlement resistance
2Strength
If strength is increased to 1 GPa or greater, then ultrahigh strength is achieved, but hydrogen delayed fracture resistance is significantly reduced
Solution Approach 1:
By changing the temperature parameter to cryogenic conditions during rolling, the invention achieves ultrahigh strength through a different mechanism (grain refinement via low-strain cryogenic rolling) that does not involve the microstructural features (high dislocation density, fine grain boundaries) that promote hydrogen embrittlement in conventionally strengthened materials
Solution Approach 2:
The invention converts the typically harmful effect of cold temperature (which usually increases brittleness) into a beneficial effect. The cryogenic temperature enables unique deformation behavior that refines grains and enhances strength while simultaneously improving hydrogen delayed fracture resistance, turning a potential harm into a benefit
3Strength
If general plastic working methods are used to harden material, then strength is increased, but strength can only reach about 1 GPa, not ultrahigh strength
Solution Approach 1:
The invention changes the temperature parameter to cryogenic conditions and reduces the strain parameter, transforming the conventional hardening approach into a grain-refinement-based strengthening mechanism. This enables achievement of ultrahigh strength (exceeding 1 GPa) through a manufacturable process that combines annealing with low-strain cryogenic rolling
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 ultrahigh strength and improved hydrogen delayed fracture resistance, suitable for extreme environments, with enhanced productivity and applicability in industries requiring high strength and resistance, such as bolts and hydrogen pipes.
Implementation Method 1
annealing and homogenizing an initial alloy material at 1000 to 1200° C. for 1 to 24 hours
Implementation Method 2
rolling the annealed and homogenized initial alloy material into a rod at a cryogenic temperature of −100 to −200° C.
Implementation Method 3
a high-entropy alloy having intersecting twins as a microstructure, and secondary fine twins formed in the intersecting twins
Data Source
AI summary
A high-entropy alloy having ultra-high strength and high hydrogen embrittlement resistance due to formation of a microstructure at a low strain may be produced without a severe plastic deformation.A method for producing the high-entropy alloy includes (a) annealing and homogenizing an initial alloy material at 1000 to 1200° C. for 1 to 24 hours; and (b) rolling the annealed and homogenized initial alloy material into a rod, at a cryogenic temperature of −100 to −200° C. while pressing the initial alloy material in multi-axial directions at a strain of 0.4 to 1.2, thereby to produce the high-entropy alloy having intersecting twins as a microstructure, and secondary fine twins formed in the intersecting twins, wherein the initial alloy material contains Co of 5 to 35%, Cr of 5 to 35%, Fe of 5 to 35%, Mn of 5 to 35%, and Ni of 5 to 35%, based on weight %.