The effect of hydrogen on the mechanical properties of high purity iron III. The dependence of softening in specimen size and charging current density

Abstract

The effect of hydrogen charging on the flow stress of high purity iron was investigated for wide ranges of specimen size, charging current density and strain rate. The amount of softening was analyzed in terms of these variables and is assumed to be proportional to the average hydrogen concentration in the matrix, which is determined by the balance between hydrogen supply from the surface and hydrogen trapping by newly produced dislocations. The results are well explained. Hardening was observed at low temperatures and under a large charging current. The strain rate sensitivity of the flows stress in hydrogen-charged specimens was measured. The results are also explained in terms of hydrogen-dislocation interactions.