Austenitic Stainless Steel Composition for Hydrogen Resistance
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Solution Overview
Problem
Existing austenitic stainless steels face challenges in achieving high tensile strength and excellent hydrogen brittleness resistance while maintaining a low production cost, as they often require a high content of alloying elements like V and Nb for these properties.
Innovation Solution
An austenitic stainless steel material with a chemical composition of C: 0.100% or less, Si: 1.00% or less, Mn: 5.00% or less, Cr: 15.00 to 22.00%, Ni: 10.00 to 21.00%, Mo: 1.20 to 4.50%, P: 0.050% or less, S: 0.050% or less, Al: 0.100% or less, N: 0.100% or less, and Cu: 0 to 0.70%, with a dislocation cell structure ratio of 50 to less than 80% and a number density of precipitates with a long axis of 1.0 μm or more of 5.0 per 0.2 mm2 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a large amount of alloying elements such as V and Nb are added to form carbides and carbo-nitrides for the pinning effect, then the tensile strength and hydrogen brittleness resistance are improved, but the production cost increases
Solution Approach 1:
The patent changes the chemical composition parameters by reducing the content of expensive alloying elements (V: 0.01-1.0% to 0.01-0.5%, Nb: 0.01-0.50% to 0.01-0.30%) while optimizing other elements (Ni: 12.0% or more to 10.00-21.00%, Cr: 15-30% to 15.00-22.00%, Mo: 0-3.0% to 1.20-4.50%). This parameter optimization achieves the required tensile strength (1000 MPa or more) and hydrogen brittleness resistance without relying heavily on expensive V and Nb additions, thereby reducing production cost while maintaining performance
Solution Approach 2:
The patent replaces expensive long-term alloying elements (V, Nb) with more cost-effective alternatives through optimized combinations of Ni, Cr, Mo, and minor elements. The invention uses cheaper elements in optimized quantities to achieve the same pinning effect and strength properties, effectively substituting expensive materials with more economical ones
2Reliability
If a large amount of alloying elements such as V and Nb are added to form carbides and carbo-nitrides for the pinning effect, then the hydrogen brittleness resistance is improved, but the production cost increases
Solution Approach 1:
The patent optimizes chemical composition parameters to achieve hydrogen brittleness resistance through a balanced approach: reducing V to 0.01-0.5% and Nb to 0.01-0.30%, while increasing Ni to 10.00-21.00% and Cr to 15.00-22.00%. This parameter reconfiguration maintains the pinning effect and hydrogen brittleness resistance required for high-pressure hydrogen environments without the high production cost associated with large V and Nb additions
Solution Approach 2:
The patent creates a composite alloy system where multiple elements (Ni, Cr, Mo, Mn, Si) work synergistically to achieve hydrogen brittleness resistance. Instead of relying on a single expensive element system (V-Nb), the invention combines several more affordable elements in optimized proportions, creating a composite material system that achieves the same protective effect at lower cost
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 austenitic stainless steel material achieves high tensile strength and excellent hydrogen brittleness resistance without relying on the pinning effect of precipitates, thereby reducing production costs.
Implementation Method 1
deformation of crystal grains is suppressed by the pinning effect and the crystal grains are refined
Implementation Method 2
carbo-nitrides finely precipitating, deformation of crystal grains is suppressed by the pinning effect
Data Source
AI summary
In the austenitic stainless steel material of the present disclosure, the chemical composition consists of, by mass %, C: 0.100% or less, Si: 1.00% or less, Mn: 5.00% or less, Cr: 15.00 to 22.00%, Ni: 10.00 to 21.00%, Mo: 1.20 to 4.50%, P: 0.050% or less, S: 0.050% or less, Al: 0.100% or less, N: 0.100% or less, and Cu: 0 to 0.70%, with the balance being Fe and impurities, and an austenite grain size No. determined in accordance with ASTM E112 is from 5.0 to less than 8.0, and in a cross section perpendicular to the longitudinal direction of the austenitic stainless steel material, the dislocation cell structure ratio is from 50 to less than 80%, and the number density of precipitates with a long axis of 1.0 μm or more is 5.0 per 0.2 mm2 or less.