Abstract
The effects of hydrogen charge and hydrogen environment on crack propagation of low alloy steel, SCM440H was investigated focusing on crack closure behavior. The test frequency was 28.4Hz. The stress ratio was -1, 0 and 0.6. Crack propagation was accelerated by hydrogen charge. However crack closure behavior was the same for that obtained by uncharged material. Crack propagation rate in hydrogen gas environment was decreased than in air. Higher crack opening stress was obtained comparing the test in hydrogen gas and that in air.
