Effect of strain rate on tensile test results in hydrogen and other concerns

Tensile tests of an X52 pipeline steel were conducted in air and in hydrogen gas at strain rates covering five orders of magnitude. Properties such as elastic modulus, yield strength, and ultimate tensile strength were unaffected by hydrogen or by strain rate. Ductility was greatly reduced in hydrogen, compared to in-air, with a moderate decrease of ductility with decreasing strain rate. Different methods of calculating the ductility, such as elongation to failure and reduction in area, are discussed, as are the consequences of these methods on the calculated Hydrogen Embrittlement Index.