Electrochemical Mitigation of hydrogen Environment Embrittlement of Ultra-High Strength AerMet(Trademark) 100
2006
Al-Ghamdi, Samil | Scully, John R.
The goal of this research is to extend the potential region of high toughness in an ultra-high strength steel (UHSS) to anodic and cathodic potentials where hydrogen environment embrittlement (HEE) is normally observed due to hydrogen uptake in the absence of inhibitors. This is being explored through the investigation of several selected chemical inhibitors (anodic inhibitors and cathodic blocking agents). The research is conducted in three stages. The effect of inhibition on lowering hydrogen production and ingress (absorption) is determined using planar coupons under conditions representative of crack tips. Studies are then extended to rescaled crevices that model occluded sites of much smaller dimensions (will not be discussed in this paper). Finally, verification of chemical inhibition of HEE susceptibility, in fracture experiments, is exhibited by a restoration in toughness and/or a reduction in crack growth rate on fatigue pre-cracked specimen. Fracture experiments are performed at various applied potentials in a marine environment. This research is part of an overall scheme to combine the study of inhibition with the control of metallurgical purity and hydrogen trap states, as well as tailored cathodic protection to optimize the fracture toughness of UHSS in marine environments. The long term goal is to provide a coupled strategy to mitigate HEE of modem high strength steels.
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