Relationship between Hydrogen Absorption and Corrosion Behavior of Ti-6Al-4V Alloy Immersed in Acidic Fluoride Solutions

Abstract

The relationship between hydrogen absorption and the corrosion behavior of Ti-6Al-4V alloy has been examined by immersing the alloy in acidulated phosphate fluoride (APF) solution with various concentrations. Upon immersion in 0.1 mass% APF solution, no hydrogen absorption is observed despite the occurrence of general corrosion. In 0.2% APF solution, slight hydrogen absorption occurs soon after immersion, and then the surface of the specimen becomes uniformly covered with a crystalline corrosion product (Na 3 AlF 6 ), thereby inhibiting further hydrogen absorption. In APF solutions with concentrations higher than 0.4%, the amount of absorbed hydrogen increases with increasing concentration of APF solution and immersion time. The type and morphology of corrosion products sensitively depend on the concentration of APF solution. Upon immersion in 0.4% APF solution, crystalline and massive Na 3 AlF 6 are observed on the surface of the specimen. In 1.0% and 1.5% APF solutions, Na 3 AlF 6 with a foldlike shape and granular Na 3 AlF 6 and Na 3 TiF 6 are observed. In 2.0% APF solution, only granular Na 3 TiF 6 is observed. The corrosion potentials and anodic polarization curves are analogous in all APF solutions except the 0.2% and 0.4% APF solutions. In contrast, the current density of cathodic polarization curves increases with the concentration of APF solution. The results of the present study suggest that the corrosion products play an important role in the hydrogen absorption behavior of Ti-6Al-4V alloy.

Effect of Hydrogen Precharging on Mechanical and Electrochemical Properties of Pure Titanium

“…In addition, when titanium components were used under hydrogenation environments, such as seawater, their service life would usually be determined by their corrosion resistance. However, current researches generally focused on the extremely acidic mediums such as nitric, sulfuric, and hydrochloric acid, [16][17][18][19][20] but rarely involve saline medium such as NaCl solution. [21] Meanwhile, as the components continue to work in those saline mediums, the dissociated hydrogen would constantly adsorb and react with titanium on the surface of these components, resulting in changes in their corrosion resistance, DOI: 10.1002/adem.201901182…”

Modulating Hydrofluoric Acid Reactivity and Corrosion Effects of Acidizing Fluids for Different Metallurgies: Titanium, Steel, and Chrome Tubing

“…Most of the research activity on Ti alloys and HF acid and F (fluoride) has been peripheral to the oilfield industry (Affrossman et al 2001;Al-Mayouf et al 2004;Fujita et al 2009;Rosalbino et al 2012;Divi and Grauman 2013), and even fewer studies can be identified addressing this topic within the industry publications (Schutz 2001;Baxter et al 2007;Pascarella and Reyes 2014). Offshore and deepwater assets are among the most intricate facilities in the oil and gas industry.…”

“…While the final equilibrium state of the dissolution (oxidation) products is typically titanium hexafluoride and pentafluoride, kinetically there are different species involved in the anodic process (Ti ϩ , Ti 2ϩ , Ti 3ϩ ) (Sutter and Goetz-Grandmont 1990;Fujita et al 2009;Fasmin et al 2015). It needs to be considered that the electrochemical steps are occurring in a heterogeneous medium-the metal surface immersed in a complex electrolyte-further complicating the anodic/cathodic processes (Hua et al 2004;Kong 2010).…”