THE SALT CORROSION OF TITANIUM ALLOYS AT ELEVATED TEMPERATURES
CRUCIBLE STEEL CO OF AMERICA MIDLAND PA
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The corrosion of Ti by salt below 1100F is an over-all oxidation process that proceeds by the following steps 1 chloride salt reacts with titanium and surface oxides with the liberation of chlorine 2 chlorine attacks titanium metal and 3 titanium chlorides oxidize. The reaction is sustained by a diffusion of salt into the oxide layer and b continued regeneration of chlorine. Accelerated attack above 1100F is the result of a liquid salt phase that forms and improves contact between alloy and corrodent. The attack of stressed super-alpha titanium alloys, processed below the beta transus, is centered in the grain boundaries. Alloys processed at higher temperatures corrode more extensively and crack transgranularly indicating that alloy partitioning occurs and results in thermal sensitization. Chlorine is the primary cracking agent.
- Properties of Metals and Alloys