Effects of hydrogen on thermally activated dislocation motion in iron

In a study of decarburized Armco iron and an Fe-0.17wt.%Ti alloy, thermal activation parameters such as m* and A* were measured, in both the presence and the absence of dissolved hydrogen. It was found that hydrogen did not significantly alter the thermal activation parameters. Since it is accepted that thermally activated dislocation motion in iron is controlled by Peierls-Nabarro barriers at low temperatures, this finding means that hydrogen predominantly affects the flow stress of iron through its interaction with other solutes such as carbon and titanium. This is consistent with fundamental deformation studies on iron as well as with previous work on hydrogen effects in iron.