SEDL / STP / STP397-EB / STP46434S

Salt Stress Corrosion of Ti-8Al-1Mo-1V Alloy Sheet at Elevated Temperatures

Heimerl, G. J.
Assistant headPersonal member ASTM, NASA Langley Research Center, Hampton, Va.

Braski, D. N.
Materials engineer, aerospace engineer, and materials engineer, NASA Langley Research Center, Hampton, Va.

Royster, D. M.
Materials engineer, aerospace engineer, and materials engineer, NASA Langley Research Center, Hampton, Va.

Dexter, H. B.
Materials engineer, aerospace engineer, and materials engineer, NASA Langley Research Center, Hampton, Va.

Pages: 21    Published: Jan 1966

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Abstract

Many small self-stressed and residual-stress specimens were coated with salt, exposed up to 6400 hr at 400 to 600 F, and tested in compression and bending at room temperature to determine the stress corrosion cracking. Of the various salts, sodium chloride (NaCl) was the most corrosive, and thin coatings were more damaging than thick. A decrease in oxygen and air pressure reduced stress corrosion, but the role of moisture and air velocity is still in doubt. Short thermal cycles of 2 or 4 hr from room temperature to 550 F produced less corrosion. Titanium dichloride (TiCl²) was identified as a corrosion product, but the corrosion mechanism is unknown. Surface treatments, such as shot peening, nickel plating, vibratory cleaning, and polyimide coatings, prevented corrosion up to 2000 hr at 600 F.