Hydrogen Steel Microstructure Fatigue Resistance

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Solution Overview

Problem

Hydrogen storage tanks used in high-pressure hydrogen atmospheres face challenges with fatigue crack propagation and hydrogen embrittlement, limiting their service life and requiring expensive materials like austenitic stainless steels for safety, which increases costs.

Innovation Solution

A steel structure with a dual-phase microstructure comprising bainite, martensite, or pearlite with a balance of ferrite is developed, which reduces fatigue crack propagation and enhances hydrogen embrittlement resistance, allowing for safer and more cost-effective high-pressure hydrogen storage solutions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If austenitic stainless steels are used to resist hydrogen embrittlement, then hydrogen embrittlement resistance is improved, but material cost increases

Engineering Contradiction:

Improvehydrogen embrittlement resistanceVSAvoidmaterial cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the microstructural parameters of low-alloy steel by controlling the cooling rate and tempering temperature to produce a dual-phase microstructure (ferrite + bainite/martensite), thereby improving hydrogen embrittlement resistance without using expensive austenitic stainless steels

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite microstructure within the steel by combining soft ferrite phase with harder bainite or martensite phase, achieving both mechanical strength and resistance to hydrogen embrittlement in a cost-effective low-alloy steel formulation

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If low-alloy steel is used to reduce cost, then material cost decreases, but hydrogen embrittlement resistance worsens

Engineering Contradiction:

Improvematerial costVSAvoidhydrogen embrittlement resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates local quality differences within the steel microstructure by distributing harder bainite or martensite phases within a ferrite matrix, providing localized resistance to hydrogen embrittlement while maintaining overall cost-effectiveness

Inventive Principle:

Principle #3Local quality

3Strength

If steel thickness is increased to withstand high pressure, then pressure resistance is improved, but manufacturing cost increases

Engineering Contradiction:

Improvepressure resistanceVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The invention changes the material properties by creating a dual-phase microstructure with enhanced mechanical strength, allowing thinner wall thickness to achieve the same pressure resistance, thereby reducing manufacturing cost

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP2980247B1Method for producing a steel structure for hydrogen gas

Publication Date: 2023.10.18 JFE STEEL CORP

AI summary

Provided is a steel structure for hydrogen gas such as a hydrogen storage tank or a hydrogen line pipe which achieves a lower fatigue crack propagation rate in a high-pressure hydrogen atmosphere than steels used in the related art and has high hydrogen embrittlement resistance. The steel structure for hydrogen gas, which has high hydrogen embrittlement resistance in high-pressure hydrogen gas, has a steel microstructure including any one of 10% to 95% of bainite on an area-ratio basis, 10% to 95% of martensite on an area-ratio basis, and 10% to 95% of pearlite on an area-ratio basis, with the balance being substantially ferrite.