Turley, R. V.
Metallurgist, materials research and process engineering, Douglas Aircraft Co., Long Beach, Calif.
Avery, C. H.
Head, Douglas Aircraft Co., Long Beach, Calif.
Pages: 30 Published: Jan 1966
Titanium alloys 6Al-4V, 8Al-1Mo-1V, 4Al-3Mo-1V, 5Al-2.5Sn, and RS-140 were evaluated for susceptibility to elevated-temperature static and dynamic sea-salt stress cracking to determine the most promising alloys for application to advanced aircraft. The nature of this cracking was also studied for evidence that would reveal the fundamental mechanisms involved. All alloys were susceptible to stress-corrosion cracking, and the susceptibility was increased with elevated temperature. Alloy 4Al-3Mo-1V was the most resistant, and 5Al-2.5Sn was least resistant. Alloy 8Al-1Mo-1V was the only one susceptible to corrosion fatigue. Fatigue precracks, anodizing, thickness, and grain direction had little or no effect on stress-corrosion susceptibility. Welding and stress relieving increased the stress-corrosion susceptibility. Cracks initiated and propagated from corrosion grooving at grain boundaries and transgranular crystallographic planes without relating to pitting, roughness, or other surface irregularities. Extended research to reveal mechanisms operative during stress corrosion of titanium is recommended as a means of understanding the factors which reduce or increase resistance to stress-corrosion cracking.
titanium alloys, corrosion, stress corrosion, salt, fatigue
Paper ID: STP46425S