Effect of Different Testing Parameter on J-R Curves in Gaseous Hydrogen

Abstract J-resistance (J-R) curve testing at slow displacement rates is emerging as the most suitable test for determination of fracture toughness of line pipe steels working in gaseous hydrogen environments. The ANSI/CSA CHMC1 standard has extrapolated the ASTM E1820 procedure to testing in pressurized H2 conditions. Particularly, the Compact Specimen (CT) of ASTM E1820 is the most common geometry used in the determination of fracture toughness in high pressure hydrogen. Although, ASTM E1820 establishes very clear limits of the different variables that could affect the test results in air (i.e.: loading rate, a/W, specimen proportions, dimensional requirements, etc.), some of the requirements in the standard have not been explored for J-R testing in high pressure hydrogen. In the present paper a numerical simulation study of crack-tip constraint is performed on the CT specimen with a/W ratios encompassing the dimensional limits of ASTM E1820. Experimental testing of CT specimens within the same limits are performed to elucidate if those parameters, so well established for tests in air, are still valid in the case of testing in high-pressure hydrogen environments.