Initiation behavior of fatigue crack from corrosion pits
Nakajima Masaki; Tokaji Keiro
Abstract:Corrosion fatigue tests in 3%NaCl aqueous solution have been conducted on a low carbon steel, S10C, a stainless steel, SUS304, and an aluminum alloy, A2024-T4, in order to clarify their crack initiation behavior from corrosion pits. The size of corrosion pits at which crack was generated was plotted on a log-normal probability paper. It was found that the size of corrosion pits increased with decreasing stress level. The stress intensity factor of a corrosion pit at which crack initiation occurred was calculated by regarding the corrosion pit as a crack. The results were plotted on a log-normal probability paper, indicating that the stress intensity factor increased with increasing stress level in S10C and A2024-T4, but it was irrespective of stress level in SUS304. The stress intensity values obtained ranged 0.51 - 2.33 Mpam1/2 in S10C, 0.37 - 1.40 Mpam1/2 in SUS304 and 0.21 - 1.21 Mpam1/2 in A2024-T4. Key Words:cprrosion fatigue, corrosion pit, crack initiation, statistical analysis, carbon steel, stainless steel, aluminum alloy