SEDL / STP / STP397-EB / STP46431S

Basic Mechanisms of Stress-Corrosion Cracking of Titanium

Rideout, S. P.
Research supervisor, Nuclear Materials Div. and metallurgists, E. I. du Pont de Nemours and Co., Aiken, S. C.

Louthan, M. R.
Research supervisor, Nuclear Materials Div. and metallurgists, E. I. du Pont de Nemours and Co., Aiken, S. C.

Selby, C. L.
Research supervisor, Nuclear Materials Div. and metallurgists, E. I. du Pont de Nemours and Co., Aiken, S. C.

Pages: 15    Published: Jan 1966

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Abstract

Prepolished strips of Ti-8Al-1Mo-1V, stressed to the yield point at 650 F, cracked when exposed to either chloride, iodide, or bromide salts. Cracking was most severe in specimens exposed to pure sodium chloride (NaCl). Chemical analyses of corrosion products formed by NaCl exposures showed that aluminum was preferentially attacked. Autoradiographic techniques with radiotracers H³, Cl³⁶, and Na²² were used to study the distribution of those elements in salt-coated specimens, and the results suggested that hydrochloric acid (HCl) and sodium hydroxide (NaOH) were produced by salt-metal-water reactions. Specimens exposed to HCl gas alone cracked within short times, but no cracking was produced by NaOH exposures. Experimental results can be interpreted to support the hypothesis that hot-salt cracking occurs by hydrogen embrittlement.