Effect of Strain Rate on Stress Corrosion Cracking of TC4-0.55% Fe Alloy in Simulated Seawater Solution

The stress corrosion cracking (SCC) performance of TC4-0.55% Fe alloy in simulated seawater solution was investigated by electrochemical measurements, slow strain rate test (SSRT) and scanning electron microscopy (SEM). The effect of strain rate (changed from 3.3×10^-6 s^-1-10.0×10^-6 s^-1) on SCC behavior of the alloy was revealed. The results showed that TC4-0.55% Fe alloy possessed the maximum SCC susceptibility at the strain rate of 5.0×10^-6 s^-1 in the simulated seawater solution, the fracture surface was dominated by flattened dimples, with obvious tearing edges between the dimples, and the quasi-cleavage fracture surface appeared in the middle region of the fracture. When the strain rate was higher than 6.6×10^-6 s^-1, the fracture surface was changed from small and shallow dimples to large and deep dimples. Therefore, tensile stress made the specimen fractured rapidly at high strain rates, and the SCC susceptibility of the alloy was very small, its fracture showed typical ductile fracture with appreciable dimples.