Two-Phase Stainless Steel Diaphragm for Pressure Sensors
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Solution Overview
Problem
Metal elastic elements used in pressure sensors face challenges with corrosion resistance and resilience, particularly when subjected to sudden pressure changes due to water hammer, leading to incomplete recovery to the original shape, which affects sensing accuracy.
Innovation Solution
A diaphragm composed of a two-phase stainless steel with a specific composition (24-26% Cr, 2.5-3.5% Mo, 5.5-7.5% Ni, 0.03-0.3% N, and balanced Fe) is developed, providing high proof stress, excellent corrosion resistance, and improved resilience, with a marble-like structure and fiber texture oriented parallel to the thickness direction, allowing for reduced residual displacement and variation in resilience among products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the proof stress or strength of the material is enhanced to improve elastic deformability, then the resilience to return to point 0 is improved, but the deviation of resilience increases and reproducibility deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters (Cr: 24-26%, Mo: 2.5-3.5%, Ni: 5.5-7.5%, N: 0.08-0.3%) and heat treatment parameters (solution treatment temperature, aging temperature, aging time) to achieve optimal balance between proof stress and resilience deviation. This systematic parameter optimization resolves the contradiction by finding the precise parameter window where both high strength and low deviation coexist.
Solution Approach 2:
The patent creates a composite microstructure consisting of austenite phase and martensite phase within the stainless steel. This dual-phase composite structure combines the ductility and elasticity of austenite with the high strength of martensite, achieving both high proof stress and consistent resilience recovery. The composite material approach allows the material to exhibit both high strength and reliable elastic recovery behavior.
2Object-affected harmful factors
If a two-phase stainless steel with sufficient proof stress is used, then the corrosion resistance is improved, but the expected resilience under sudden pressure change is not achieved
Solution Approach 1:
The patent modifies the compositional parameters by adding specific amounts of nitrogen (0.08-0.3%) alongside the standard two-phase stainless steel composition (24-26% Cr, 2.5-3.5% Mo, 5.5-7.5% Ni). This parameter adjustment enhances both the corrosion resistance through improved passive film formation and the resilience through solid solution strengthening, simultaneously addressing both requirements without compromise.
Solution Approach 2:
The patent develops a refined two-phase composite structure with controlled distribution of austenite and martensite phases, where the martensite phase provides high strength and corrosion resistance while the austenite phase ensures elastic recoverability. This optimized composite microstructure overcomes the limitation of conventional two-phase stainless steel by achieving both corrosion resistance and water hammer resilience.
3Strength
If the material strength is increased to improve elastic region, then the ability to store load as elastic energy is improved, but the deviation of resilience increases
Solution Approach 1:
The patent implements precise parameter control through defined compositional ranges (Cr: 24-26%, Mo: 2.5-3.5%, Ni: 5.5-7.5%, N: 0.08-0.3%) and specific heat treatment parameters (solution treatment at 1000-1100°C, aging at 400-600°C for 1-12 hours). This rigorous parameter specification ensures that the material achieves high strength while maintaining consistent resilience properties across production batches, resolving the deviation issue.
Solution Approach 2:
The patent applies preliminary action through controlled aging treatment performed after solution treatment and before final product formation. This pre-established microstructure with dispersed precipitates in the matrix prepares the material with optimized elastic properties and consistent resilience behavior, preventing later variations and ensuring manufacturing precision.
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 two-phase stainless steel diaphragm exhibits high proof stress, excellent corrosion resistance, and improved resilience, maintaining accurate pressure detection performance even under sudden pressure changes, with reduced residual displacement and variation, enhancing the stability and reliability of pressure sensors.
Implementation Method 1
a material including a larger elastic region has a higher ability to store the load as an elastic energy
Implementation Method 2
when a stress exceeding the elastic deformability of the element is generated by a sudden pressure increase, the metal elastic element may not be restored to the point 0
Data Source
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AI summary
An object of the present invention is to provide a metal elastic element which is suitable for sensing or the like of a fluid pressure change and exhibits favorable resilience even in the case of receiving a sudden pressure change, and also provide a diaphragm using the same. A metal elastic element of the present invention is composed of a two-phase stainless steel having a γ-phase and an α-phase, wherein the area ratio of the γ-phase is 40% or less, and the two-phase structure is a marble-like metal structure. In the invention, it is preferred that the element has a fiber texture in which <111>γ and <110>α are preferentially oriented parallel to the thickness direction.