Austenitic Stainless Steel Gasket for High-Temperature Gas Sealing
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Solution Overview
Problem
Existing heat-resistant metal gaskets face challenges in maintaining gas leak resistance and corrosion resistance while being cost-effective, especially when exposed to high temperatures, due to issues with material strength, surface roughness, and processing defects.
Innovation Solution
An austenitic stainless steel sheet with a specific chemical composition and processing parameters, including controlled hardness, surface roughness, and strain index, is used to create a metal gasket with enhanced gas leak resistance and cost-effectiveness for high-temperature applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a large amount of martensite phase is contained to increase yield stress, then strength is improved, but gas seal capability deteriorates due to surface roughening and necking
Solution Approach 1:
The patent changes the material parameters by controlling the half width of austenite (311) plane peak to 0.10-1.60° and ordinary temperature hardness to 430 NV or less, optimizing the balance between strength and formability to prevent surface roughening while maintaining adequate yield stress for gas seal capability
Solution Approach 2:
The patent creates a composite microstructure consisting of austenite matrix with controlled strain (half width 0.10-1.60°) and precipitates, combining the ductility of austenite with the strength from precipitates to achieve both good formability and adequate strength without martensite-induced surface defects
2Strength
If precipitation strengthened material is used to achieve effective strengthening at 600-800°C, then high temperature strength is improved, but cost increases due to expensive Ni content
Solution Approach 1:
The patent optimizes the Ni content parameter to a specific range (7.0-17.0%) that provides sufficient precipitation strengthening at 600-800°C while controlling cost, and controls the half width of austenite (311) plane peak to achieve the required strength without excessive Ni addition
Solution Approach 2:
The patent achieves localized strengthening through controlled precipitate distribution in the austenite matrix, providing high temperature strength where needed while maintaining overall cost-effectiveness by optimizing rather than maximizing Ni content
3Strength
If cold rolling finishing is applied to increase strength, then yield stress is improved, but surface roughness increases and gas seal capability deteriorates
Solution Approach 1:
The patent changes the surface quality parameter by controlling the half width of austenite (311) plane peak to 0.10-1.60° and ordinary temperature hardness to 430 NV or less, which prevents excessive surface roughening during cold rolling while maintaining adequate strength through optimized material structure
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 heat-resistant metal gasket that is easily processed, exhibits excellent gas leak resistance, and maintains cost-effectiveness, while ensuring adequate corrosion resistance and oxidation resistance at temperatures ranging from 600 to 800°C.
Implementation Method 1
an austenitic stainless steel sheet for a heat resistant metal gasket, having a chemical composition containing from 0.015 to 0.200% of C, from 1.50 to 5.00% of Si, from 0.30 to 2.50% of Mn, from 7.0 to 17.0% of Ni, from 13.0 to 23.0% of Cr
Implementation Method 2
A precipitation strengthened material, such as NCF 625 and NCF 718 defined in JIS G4902 (corrosion-resisting and heat-resisting superalloy plates and sheets) and SUH660 defined in JIS G4312 (heat-resisting steel plate), is effective for precipitation strengthening at a temperature of from 600 to 800° C.
Implementation Method 3
An SUS301 or SUS431 series material represented by those described in PTLs 1, 2, and 3 undergoes significant softening since the heating temperature is close to the decomposition temperature of the martensite phase
Data Source
AI summary
To provide a heat resistant metal gasket that is controlled to have a strength level (ordinary temperature hardness) capable of facilitating processing, and has excellent gas leak resistance.An austenitic stainless steel sheet for a metal gasket, having a chemical composition containing from 0.015 to 0.200% of C, from 1.50 to 5.00% of Si, from 0.30 to 2.50% of Mn, from 7.0 to 17.0% of Ni, from 13.0 to 23.0% of Cr, and from 0.005 to 0.250% of N, all in terms of percentage by mass, containing, as necessary, at least one of Mo, Cu, Nb, Ti, V, Zr, W, Co, B, Al, REM (rare-earth element except for Y), Y, Ca and Mg, with the balance of Fe and unavoidable impurities, having an ordinary temperature hardness of 430 HV or less, having a half width of a peak of an austenite crystal (311) plane in an X-ray diffraction pattern of a cross section perpendicular to a sheet thickness direction of from 0.10 to 1.60°, and having a surface roughness Ra of 0.30 μmm or less.