Strain-Life Performance in Hydrogen of a Dot Pressure Vessel Steel

Strain-life testing of a 4130 pressure vessel steel was conducted in air and in a high-pressure gaseous-hydrogen environment. Hydrogen causes an order of magnitude decrease in lifetime compared to in-air performance at the same strain-amplitudes. This decrease in lifetime in hydrogen is accompanied by various effects, such as a shift in the cyclic stress-strain curve, different influences on the elastic and plastic components of the strain-life data, and a distinct difference in the evolution of the microstructural texture prior to failure. For comparison, preliminary data from testing of a higher strength pressure vessel steel is presented, showing a difference in elastic/plastic partitioning may be accompanied by a difference in reduction in lifetime due to hydrogen.