Design of ion-implanted hydrogen contamination barrier layers for steel

Abstract

The results of electrochemical hydrogen permeation tests are presented for a high strength low alloy steel of the type API 5L X-65 in the non-implanted and nitrogen-ion-implanted conditions. The material was implanted under a variety of conditions to produce three series of samples, each with a characteristic implanted layer depth. The results for the implanted materials, when compared with the maximum hydrogen permeability value determined for the non-implanted material, indicate the existence of a critical implanted layer thickness. When the depth of an implanted layer is less than this critical value, the hydrogen permeability of the composite material (implanted layer and substrate) is observed to increase (relative to the non-implanted material). For layer thicknesses equal to or greater than the critical value, the permeability is unnaffected or reduced respectively. It is concluded that nitrogen-ion-implanted layers on steel are well suited for impeding hydrogen contamination and that the techniques employed in this study may be exploited to design surface-engineered hydrogen contamination barrier layers for steel.