Ferrite-Martensite Steel Fuel Element Welding
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Solution Overview
Problem
The operational durability of fuel elements for fast-neutron reactors made of high-chromium ferrite-martensite steels is compromised by the tendency to form quenching structures and cold cracks, requiring additional tempering processes that increase manufacturing complexity and cost.
Innovation Solution
A welded joint is formed between a fuel element casing and a plug using argon-arc welding, where the casing is made of ferrite-martensite steel and the plug is made of ferrite steel, with specific parameter ratios to ensure a ferrite phase in the weld seam, eliminating the need for subsequent heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If argon-arc welding is used to join high-chromium ferrite-martensite steels, then the fuel element can be sealed, but quenching structures and cold cracks form after welding
Solution Approach 1:
The invention changes the material parameters by using ferrite steel for the plug instead of ferrite-martensite steel, and adjusts welding parameters (current 80-120A, speed 8-15 m/h) to achieve a ferrite phase in the weld seam that prevents quenching structures and cold cracks
Solution Approach 2:
The invention uses composite material structure with ferrite-martensite steel casing and ferrite steel plug, creating a welded joint with controlled phase composition (ferrite phase with 8-15% austenite) that combines the benefits of both material types
2Manufacturing precision
If additional tempering operation is performed to produce high-quality welded joints, then weld quality improves, but manufacturing complexity and cost increase
Solution Approach 1:
The invention performs preliminary action by selecting appropriate materials (ferrite steel plug) and welding parameters before welding to ensure the weld seam forms a ferrite phase that is inherently crack-resistant, eliminating the need for subsequent tempering operations
Solution Approach 2:
The invention extracts the tempering operation from the manufacturing process by designing a welding system that produces high-quality joints directly without requiring additional heat treatment steps
3Manufacturing precision
If tempering is applied to welded seams of fuel elements loaded with fuel, then weld quality improves, but the process becomes even more complex and costly
Solution Approach 1:
The invention performs preliminary action by designing the welding process to produce high-quality, crack-resistant joints in a single step, eliminating the need for subsequent tempering operations on already-loaded fuel elements
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 approach simplifies the manufacturing process by creating a high-quality, durable welded joint without the need for tempering, enhancing the mechanical strength and corrosion resistance of the fuel elements while maintaining hermetic sealing.
Implementation Method 1
connected by the argon-arc welding method
Data Source
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AI summary
The invention relates to nuclear power and can be used in the manufacture of fuel elements for nuclear reactors. Embodiments of a welded joint between a fuel element casing and a plug comprised of high-chromium steel are proposed, providing for increased durability of the sealing of nuclear reactor fuel elements as a result of the formation of a high quality welded joint between the casing and the plug without the need for subsequent heat treatment of the weld seam, which simplifies the manufacturing process. This is achieved through the formation of a ferrite phase in the metal of the seam by adjusting the structure of a joint between the casing and the plug of ferrite-martensite and ferrite steels in various combinations and by keeping the necessary ranges of the size ratios to ensure the formation of the aforesaid phase.