Effect of Cyclic Frequency on the Corrosion-Fatigue Crack-Initiation Behavior of ASTM A517 Grade F Steel

摘要: This study was conducted to investigate the effect of cyclic frequency on corrosion-fatigue crack-initiation behavior in regions stress concentration ASTM A517 Grade F steel. The tests were notched compact tension specimens at a ratio 0.1 room-temperature 3.5 percent solution sodium chloride. test results showed that life under full immersion conditions significantly less than fatigue-crack-initiation air. Moreover, no range 12 300 cpm life. data indicate possible existence limit, below which cracks did not initiate, ΔK/√ρ about 172 MPa (25 ksi). value corresponds maximum range, Δσ m x , 207 (30 ksi) and is one-fourth for limit Fatigue-crack-initiation precorroded 25 reduction limit. decrease attributed an increase caused by corrosion pits surface notch radius. Metallographic investigations initiate tip. These as microcracks form sharpening corrosion-pit tip combined influence environment loads. No relationship found between microstructure sites.