Evolution of Fractograph During Fatigue and Stress Corrosion Cracking

摘要

Fatigue and stress corrosion cracking (SCC) behaviors were studied for three landing gear steels, AerMet 100, 300M, and 4340. The three steels were subjected to identical fatigue tests in vacuum, air, and 3.5% NaCl solution and identical stress corrosion cracking tests in 3,5% NaCl solution. The variation of fatigue crack growth rate with stress intensity range and maximum stress intensity was evaluated for different stress ratios and environments. Also, the variation of SCC rate with stress intensity was investigated. Subsequently, the fatigue- and SCC-induced crack surface morphologies were examined, and the fractographic evolution was defined with respect to the stress ratio, crack growth rate, stress intensity, and environment.