Effect of high-pressure hydrogen on crack growth in carbon steel

The effect of high-pressure hydrogen and temperature on crack growth was studied in wedge-opening-load (WOL) samples of a low-carbon steel. At temperatures above 280 ‡C, a hydrogen pressure of 3 ksi gave an increasing amount of acceleration in crack growth. These conditions approached but were below that needed to give hydrogen attack (HA) in the surrounding matrix. The value ofda/dt increases exponentially with temperature, andQ is roughly equal to that for grain boundary diffusion. The growth is absent atK1 = 0 but varies little withK1 above 15 MPa√m. The value ofda/dt increases steadily with hydrogen pressure in the range of 3 to 21 MPa.