Hydrogen Absorption to Low Alloy Steels in High Pressure Gaseous Hydrogen Environments

Abstract

Effects of test temperature and plastic strain on hydrogen absorption to low alloy steels, and these effects on hydrogen embrittlement were investigated in gaseous hydrogen environments at 45 MPa. At room temperature, hydrogen did not enter into the samples with no strain, while plastic strain in gaseous hydrogen accelerated hydrogen absorption. The amount of absorbed hydrogen increased with an increase in test temperature above 50°C. Slow strain rate tests (SSRT) at room temperature gave more severe results than four point bend tests (4PBT) in gaseous hydrogen at room temperature. This was due to the acceleration of hydrogen absorption by dynamic strain in gaseous hydrogen in SSRT. Cracks hardly occurred in 4PBT after exposure in gaseous hydrogen at 150°C. The mechanism was assumed that degassing of hydrogen from the specimens during cooling or stabilization of hydrogen in the steels at elevated temperatures.