Hot salt stress corrosion cracking by silver chloride in Ti-6Al-2Sn-4Zr-6Mo

Abstract

Hot salt stress-corrosion cracking (HSSCC) of titanium alloys has been found in the presence of chloride and other halide salts. Here, a series of AgCl HSSCC tests on Ti-6246 were conducted using a two-point bending rig at 380-500°C to determine the boundary conditions of stress and temperature. Rapid failure occurred after 24 hours above 440 °C, whilst the trigger stress of HSSCC was determined to be 400 MPa at 380 °C. Energy dispersive X-ray during scanning transmission electron microscopy (STEM-EDX) suggested the formation of metallic silver and chlorides of active alloying elements Al, Sn and Zr. The transgranular fracture surface is expected to be linked to an underlying hydrogen embrittlement via hydrogen charging from the corrosion reactions.