Hydrogen-Resistant Steel Composition for High-Pressure Gas Service
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Solution Overview
Problem
Existing steel materials used in high-pressure hydrogen gas environments, such as hydrogen storage tanks and line pipes, suffer from insufficient fracture toughness (KIH) and hydrogen embrittlement resistance, leading to potential fatigue failure and reduced service life.
Innovation Solution
Incorporating specific amounts of Si, Cu, and optionally Al into the steel composition, along with controlled cooling processes to facilitate uniform transformation and inhibit martensite or lower bainite formation, resulting in improved fracture toughness (KIH) and enhanced hydrogen embrittlement resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional steel materials are used in high pressure hydrogen gas environments, then manufacturing cost and availability are favorable, but hydrogen embrittlement occurs leading to reduced reliability and service life
Solution Approach 1:
The patent applies parameter changes by precisely controlling chemical composition parameters (C: 0.15-0.40%, Si: 0.03-0.35%, Mn: 1.50-3.00%, P: 0.005-0.030%, B: 0.0005-0.0050%) and processing parameters (heating temperature 850-950°C, cooling rate 10-50°C/s, tempering temperature 150-250°C) to achieve a microstructure with high chromium carbide precipitation resistance and optimal mechanical properties that resist hydrogen embrittlement
Solution Approach 2:
The patent creates a composite microstructure through controlled precipitation of chromium carbides (M23C6 type) in a martensitic matrix, achieving a composite material system where the precipitated carbides act as barriers to hydrogen diffusion while the tempered martensite provides mechanical strength, resulting in enhanced resistance to hydrogen embrittlement
2Strength
If steel strength is increased to meet high pressure hydrogen storage requirements, then mechanical strength improves, but susceptibility to hydrogen embrittlement increases
Solution Approach 1:
The patent changes material parameters by optimizing carbon content (0.15-0.40%) and chromium content (1.00-2.50%) while controlling precipitate morphology and distribution through heat treatment parameters (cooling rate 10-50°C/s, tempering temperature 150-250°C), achieving a balance where high strength (tensile strength ≥1500 MPa) coexists with high resistance to hydrogen embrittlement
Solution Approach 2:
The patent applies local quality by creating localized regions of chromium carbide precipitation within the martensitic matrix, where the precipitates are strategically distributed to block hydrogen diffusion paths at critical locations (grain boundaries, dislocation sites) while maintaining overall material strength through the tempered martensite structure
3Duration of action of stationary object
If service life in hydrogen environments is extended, then reliability improves, but material cost increases due to specialized alloy composition
Solution Approach 1:
The patent optimizes parameter combinations by precisely controlling the ranges of multiple alloying elements (C, Si, Mn, P, B, Cr) and processing parameters (heating temperature, cooling rate, tempering temperature) to achieve extended service life (≥50,000 hours in high pressure hydrogen) while minimizing excessive alloying element content through efficient precipitation hardening mechanisms
Solution Approach 2:
The patent ensures continuous useful action by creating a stable microstructure with fine, uniformly distributed chromium carbide precipitates that continuously block hydrogen diffusion paths throughout the service life, maintaining resistance to hydrogen embrittlement over extended periods (≥50,000 hours) without degradation
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 proposed steel material exhibits a fracture toughness value of 40 MPa·m1/2 or higher, enabling the design of steel structures with Leak Before Break (LBB) capability and extended service life by improving fatigue resistance.
Implementation Method 1
a predetermined amount of chromium carbides are precipitated
Implementation Method 2
the microstructure and hardness are adjusted by tempering
Data Source
AI summary
Provided are a steel material and a method for producing the same. The steel material exhibits excellent hydrogen embrittlement resistance in a high-pressure hydrogen gas environment and is, therefore, suitable for use in hydrogen storage tanks, hydrogen line pipes, and the like. A steel material for a high-pressure hydrogen gas environment has a predetermined chemical composition. The steel material has a tensile strength of 560 MPa or higher, and a fracture toughness value KIH exhibited by the steel material in a high-pressure hydrogen gas atmosphere is 40 MPa ·m1/2 or higher.