Fraunhofer Institute for Mechanics of Materials IWMHydrogen embrittles metals, especially at high temperatures such as those found in gas turbines, electrolyzers, and heat exchangers. Existing autoclave tests are expensive, slow, and reach their limits at temperatures above 300 °C. The Fraunhofer IWM, in collaboration with partners, is developing a cost-effective hollow-specimen technique that allows materials properties under the influence of H₂ to be determined faster, more affordably, and across new temperature ranges up to 900 °C.
Efficient testing strategy for investigating microstructure-dependent materials behavior under the influence of hydrogen at elevated temperatures
Ongoing research project
Project description
Market needs and challenges
The hydrogen economy requires components that can safely come into contact with hydrogen at high temperatures, such as in electrolyzers, H₂ gas turbines, and fuel cells. Hydrogen embrittlement can lead to sudden component failure in these applications. Existing testing methods (autoclave technology) are expensive, time-consuming, available at only a few institutes, and technically limited at temperatures above approximately 300 °C. SMEs in particular can hardly afford such testing programs, which poses a significant barrier to innovation.
Project approach
The project is developing and validating the hollow specimen testing method - for the first time systematically at high temperatures (up to 900 °C) and for various test types (tensile, LCF, TMF - as a cost-effective alternative to autoclave technology. In addition, the method of hydrogen preloading followed by testing in air is being investigated. Industry-relevant nickel-based materials and austenitic steels - both conventionally and additively manufactured - are being tested to derive a broadly applicable testing strategy suitable for standardization.
Contribution to addressing challenges
By comparing the autoclave, hollow specimen, and preloading methods, a validated, significantly more cost-effective, and faster testing strategy is developed (target values: halving costs, tripling specimen throughput), which also covers temperature ranges beyond the limits of autoclave testing. This provides companies - especially SMEs - with access to reliable materials data and a practical testing methodology for the safe design of high-temperature components subjected to hydrogen stress.
Fraunhofer IWM’s work packages in the project:
Fraunhofer IWM produces hollow and solid specimens from the nickel-based materials Alloy 718 and Hastelloy X (manufactured conventionally and via additive manufacturing) and initially determines reference properties (tensile and LCF tests) without the influence of hydrogen. In the core work package, the IWM conducts tensile, LCF, and TMF tests under internal hydrogen pressure (100 bar) using the hollow specimen technique developed at the institute at temperatures up to 900 °C, both without and with prior hydrogen preloading. In addition, tests are conducted on preloaded specimens under internal H₂ pressure to evaluate the effects of hydrogen saturation. The results will include a validated high-temperature hollow-specimen test rig, comprehensive materials properties (tensile, fatigue, and creep-fatigue data) under the influence of H₂ for nickel-based alloys, and a direct comparison of methods with autoclave technology, contributing to a jointly derived, standardizable testing strategy.
Based on the project results, Fraunhofer IWM can offer industrial companies the following research and development services:
High-temperature hollow-specimen testing under hydrogen influence
Determination of tensile, fatigue, and TMF properties at temperatures up to 900 °C under internal H₂ pressure. This covers temperature ranges that cannot be achieved with autoclaves.
Cost-effective materials screening under hydrogen influence
Rapid, cost-effective evaluation of the hydrogen susceptibility of new and existing alloys.
Provision of materials data for nickel-based alloys
Reliable characteristic values (HEE index, LRF) for Alloy 718, Hastelloy X, Alloy 625, and others, for immediate use in the design of turbine, electrolyzer, and heat exchanger components.
Evaluation of additively manufactured components under hydrogen influence
Investigation of the hydrogen behavior of components manufactured using PBF-LB/M.
Consulting on testing strategies and compliance with standards
Recommendations for efficient test combinations (strain rates, hold times, preload) based on the methodology developed, which is suitable for standardization.
