Stress corrosion cracking of TC4 ELI alloy with different microstructure in 3.5% NaCl solution

Stress corrosion cracking (SCC) of TC4 ELI alloy was investigated by slow strain rate test (SSRT) with an in site electrochemical experiment in 3.5% NaCl solution. Results indicated that both lamellar microstructure (LM) and equiaxed microstructure (EM) of TC4 ELI alloy possessed a certain stress corrosion sensitivity at the strain rate from 6 × 10⁻⁵ s⁻¹ to 4 × 10⁻⁴ s⁻¹, which attained maximum at 1 × 10⁻⁴ s⁻¹. Meanwhile, the LM of TC4 ELI alloy exhibited significantly higher stress corrosion sensitivity than the EM, it could be ascribed to the higher α phase content and present of triangular grain boundaries, which promoted an active anodic reaction and facilitated the formation of hydrides. Finally, partial cleavage plane was found in TC4 ELI alloy with LM after fracture at the strain rate 1 × 10⁻⁴ s⁻¹. The SCC mechanism could be explained by the interaction of anodic dissolution along with hydrogen-induced cracking.