Hydrogen Resistance
Definition: Hydrogen resistance describes the ability of a material to withstand the action of hydrogen without suffering damaging changes such as embrittlement, cracking or decarburisation. Hydrogen can diffuse into the metal and significantly affect its mechanical properties. The assessment is particularly relevant at elevated pressure and temperature.
Practical relevance: Typical damage mechanisms are hydrogen-induced cracking (HIC), stress corrosion cracking (SCC) and high temperature hydrogen attack (HTHA). The material composition, microstructure, hardness and operating parameters are assessed. Normative references include, among others, API 941 (Nelson curves) and NACE guidelines. Material selection is decisive for plants in the hydrogen economy and refinery technology.
Decision-making perspectives:
- Technical decision-makers: Selection of suitable alloys and definition of safe operating limits.
- Purchasing/project management: Specification of hydrogen-suitable materials in technical delivery conditions.
- Science: Investigation of diffusion mechanisms and interaction with the microstructure.
- Insurance/law: Demonstration of compliant material selection in the event of hydrogen-related damage.
Typical testing or verification methods: HIC testing, slow strain rate test (SSRT), metallography, hardness testing, fracture mechanics assessment.
FAQ:
- Why is hydrogen critical for many steels?
- Hydrogen can lead to embrittlement and delayed cracking, even at moderate stresses.
