Abstract
High carbon steel wires were loaded in tension to 79% ultimate tensile strength (UTS) and cathodically charged with hydrogen. The times to failure by hydrogen embrittlement (HE) were statistically analyzed to obtain the minimum incubation time and the mean time to failure. Electrochemical measurements of the mobile hydrogen content showed that baking the wires for 2 h at 200 C was effective in reducing the lattice hydrogen concentration to the same level as in uncharged material. Baking dramatically increased the embrittlement susceptibility of the high carbon wire, however, reducing both the minimum incubation time and the mean time to failure. These unexpected findings are explained by the effect of temperature on reversible and irreversible hydrogen trapping. Baking this material is believed to release hydrogen from relatively low energy innocuous traps and allow it to concentrate in traps with higher interaction energies. Upon reloading, these sites act as significant stress concentrators, leading to more rapid failure.