Pressing need to reduce carbon-emissions have positioned hydrogen as a promising alternative to carbon-based fuels. Initial attempts have been to blend hydrogen with natural-gas. However there are challenges in adopting the proposed approach due to significant risks with compatibility of pipeline- materials due to (1) hydrogen-assisted materials degradation (2) energy-conversation (3) metering and blended-gas handling (4) measurement (5) compressibility: during transportation, pipe wall friction causes gas to lose pressure etc. Single Edge Notched bend specimens to be removed from DSN9, a high-nitrogen, austenitic stainless and X70 pipeline-steel for fracture toughness testing per ASTM E399. Specimens with a 0.1" deep EDM starter notch for fatigue pre-cracking to be used for testing. Each specimen to be pre-cracked to a depth where a/W ≥0.5 prior to testing. Rising Step Load™ Testing to identify KIscc of DSN9 vs. X70 will be performed in 3.5% NaCl aqueous solution under an imposed cathodic potential. Microstructural characterization to be conducted in TEM. KIscc of DSN9 vs. X-70 pipeline-steel under embrittling conditions to be evaluated to assess residual-plasticity of the alloys under hydrogen-charging. This is critical for designing pipelines for hydrogen transport where unstable crack-development and growth can result in gas-line explosion, vs. crack-arrestation, which should lead to confined-leakage.
