Abstract
The effect of hydrogen concentration on the monotonic and cyclic plastic deformation of polycrystalline nickel was evaluated uniaxial tensile experiments and strain amplitude-controlled cyclic testing at hydrogen concentrations of 0, 2000, and 4000 atomic parts per million. Results demonstrate that hydrogen content increases yield an increase in the work hardening rate under monotonic loading. Similar effects were also noted under cyclic loading, with increasing hydrogen concentration resulting in a higher saturation maximum tensile stress for a given applied plastic strain amplitude as well as a higher cyclic strain hardening coefficient. These results are briefly assessed in the context of the mechanistic factors controlling monotonic and cyclic plasticity, which collectively reveal that hydrogen is fundamentally altering plastic deformation processes.