Abstract
Titanium alloys are chosen for the manufacturing of components used in a marine environment. These alloys efficiently protect themselves from any damage due to this aggressive environment thanks to their passive film of titanium oxide TiO2. Most of the time, for multi-materials assemblies, titanium alloys are placed in cathode conditions when submitted to galvanic coupling or cathodic protection. These conditions could favor hydrogen evolution reaction (HER), which may lead to the material embrittlement by hydrides formation1 or high concentration of hydrogen2.
It is therefore essential to carry out a systematic approach in order to determine the intrinsic parameters and the mechanisms that lead to damage. For this purpose, a two-phase titanium alloy (α / β) TA6V ELI (grade 23) and a single phase (α) alloy commercially pure titanium (grade 2 also called T40) are studied in order to assess the impact of the nature of each phase on the sensitivity to hydrogen embrittlement in artificial seawater according to ASTM D-1141. Charging conditions are ensured by applying different cathodic potentials during various immersion durations. The hydrogen content is measured and the characterization of surface hydrides nature is achieved as a function of the cathodic potential. The aim is to understand the effects of the diffusible/trapped hydrogen and the microstructure modifications on the classical mechanical properties. In parallel, a local approach of fracture is studied.