Influence of Cl exp -- Concentration on Corrosion Fatigue Crack Growth of an Austenitic Stainless Steel

• Published in: Bulletin of the JSME 1983-08, Vol.26 (218), p.1281-1287
• Main Authors: Endo, K, Komai, D, Murayama, S
• Format: Article
• Language: English
• ISSN: 0021-3764

Corrosion fatigue crack growth rate of an austenitic stainless steel (SUS304) was measured in Cl exp -- containing water. Acceleration mechanisms of crack growth in corrosive environment were discussed, and an acceleration of da/dN in SUS304 was compared with that in a high-tension steel (HT55). The first step acceleration of da/dN in water environment from that in dry air was due to the reverse slip suppressing effect induced by water molecule adsorption. The second step acceleration at a low frequency (f = 0.1 Hz) was due to hydrogen embrittlement of plasticity-induced martensite formed at crack tips. In 3% NaCl solution at f = 0.1 Hz, the acceleration by stress-assisted dissolution was also observed. The crack opening ratio (U) was independent of Cl exp -- concentration as well as cycle frequencies. The acceleration of da/dN in SUS304 amounted to 9.2 times that in HT55, and a water environment sensitive crack growth behaviour under cyclic stresses was clear. However, there existed a threshold Delta K to commencing to accelerate da/dN from that in air, and the acceleration in HT55 exceeded that in SUS304 at f = 5 Hz near Delta K sub th .--AA