Evaluation of the Internal Hydrogen-Induced Threshold Stress Intensity Factor in 2.25Cr-1Mo Steels Determined by the Offset Potential Drop Method
The single specimen offset potential drop method has been applied to obtain the internal hydrogen-induced threshold stress intensity factor KIH in Cr-Mo steels by using small-sized 12.7-mm-thick ASTM CT-specimens (1/2T-CT).The subcommittee on Hydrogen Embrittlement in the Material Division of the Japan Pressure Vessel Research Council (JPVRC) had been investigating internal hydrogen embrittlement by using 25.4mm thick compact tension specimens (1T-CT(1/2): B = 25.4mm, W = 25.4mm, 2H = 30.5mm), to enable an adequate supply of hydrogen from the uncracked region of the specimen near a crack tip to the crack tip zone during the experiment under normal atmospheric conditions. In the present study, tests were performed on 1/2T-CT specimens under a mixed load control and grip-displacement control aimed at achieving a reduction in the test execution time. It was found that the threshold stress intensity factors for the 1/2T-CT specimens exhibited virtually the same behavior as those obtained in the previous studies using the 1T-CT (1/2) specimens.