Stainless Steel Gasket Sheet Nitrogen Refinement
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Solution Overview
Problem
Current stainless steel gasket materials face a trade-off between high strength and workability, leading to issues like wrinkles, cracks, and reduced fatigue resistance, which can result in inadequate sealing and engine performance problems.
Innovation Solution
Austenitic stainless steel sheets with refined crystal grains near the surface, achieved through nitrogen absorption and precipitation during specific heat treatments, enhance workability and fatigue properties while maintaining high strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the strength of stainless steel gasket material is increased, then the sealing capability and load-bearing capacity improve, but the workability deteriorates leading to wrinkles and cracks during bead formation
Solution Approach 1:
The patent applies local quality by creating a surface layer with refined crystal grains (average diameter 10 μm or less) through nitrogen absorption and precipitation during heat treatment, while the interior maintains coarser grains. This localized refinement at the surface where deformation occurs during bead formation improves workability without sacrificing the overall strength provided by the bulk material structure.
Solution Approach 2:
The patent changes physical and chemical parameters by controlling nitrogen content (0.01-0.05 mass%) and implementing specific heat treatment conditions (temperature range, holding time, atmosphere control) to precipitate nitrogen compounds and refine surface crystal grains. These parameter changes enable simultaneous achievement of high strength and excellent workability.
2Strength
If the strength of stainless steel gasket material is increased, then the sealing capability improves, but the fatigue resistance deteriorates due to defects from poor workability
Solution Approach 1:
The patent applies local quality by creating a surface layer with refined crystal grains (average diameter 10 μm or less) through nitrogen absorption and precipitation during heat treatment, while the interior maintains coarser grains. This localized refinement at the surface where deformation occurs during bead formation improves workability without sacrificing the overall strength provided by the bulk material structure.
Solution Approach 2:
The patent applies preliminary action by performing heat treatment before bead formation to refine the surface crystal grain structure and reduce defects in advance. This preliminary refinement prevents the formation of wrinkles and cracks during subsequent bead formation, thereby improving fatigue resistance before the component enters service.
3Strength
If conventional heat treatment is used to refine crystal grains, then the strength increases, but the workability deteriorates due to insufficient grain refinement
Solution Approach 1:
The patent uses nitrogen compounds (nitrides or nitric carbides) as an intermediary mechanism to refine crystal grains. By controlling nitrogen absorption during heat treatment and subsequent precipitation, these compounds act as grain boundary strengtheners and refinement agents, enabling superior grain refinement compared to conventional heat treatment alone.
Solution Approach 2:
The patent changes physical and chemical parameters by controlling nitrogen content (0.01-0.05 mass%) and implementing specific heat treatment conditions (temperature range, holding time, atmosphere control) to precipitate nitrogen compounds and refine surface crystal grains. These parameter changes enable simultaneous achievement of high strength and excellent workability.
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 solution provides a stainless steel sheet with excellent workability and fatigue resistance, suitable for high-performance engine gaskets, ensuring reliable sealing and reduced fuel consumption.
Implementation Method 1
nitrogen absorption and precipitation during specific heat treatments
Implementation Method 2
nitrogen compounds having a diameter of at least 10 nm and at most 200 nm are present
Implementation Method 3
achieved through nitrogen absorption and precipitation during specific heat treatments
Data Source
AI summary
A high-performance stainless steel sheet which has a high strength which is optimal for a gasket for use in high-performance engines of automobiles and motorcycles and which also has excellent workability and fatigue properties and a method for its manufacture are provided.At least in a region from the surface of the sheet up to 3 μm in the thickness direction, nitrogen compounds of at least 10 nm and at most 200 nm are present in an amount of at least 200 per 100 μm2. The number of nitrogen compounds of at least 10 nm and at most 200 nm in a region from the sheet surface up to 3 μm in the thickness direction of the sheet is at least 2 times the number of nitrogen compounds of this size in the central portion of the sheet thickness.