Environmentally Influenced Fatigue in High Strength Steels

Lee, E
Naval Air Warfare Center Aircraft Division, Aerospace Materials Division, Code 4.3.4.2, Patuxent River, MD

Vasudevan, A
Office of Naval Research, Arlington, VA

(Received 30 October 2003; accepted 26 April 2004)
JOURNAL JAI
Abstract
A study was conducted to identify the environmental influence on fatigue crack growth behavior of three high strength steels: AerMet 100, 300M, and 4340. These steels were subjected to fatigue tests under constant amplitude loading of frequency 10 Hz and stress ratios R = 0.1 and 0.9, in vacuum, air, and 3.5% NaCl solution. The fatigue crack growth was characterized with two driving force parameters, stress intensity range, DK, and maximum stress intensity, K_max. Especially, the variation of fatigue crack growth per time, da/dt, with K_max in 3.5% NaCl solution was evaluated with respect to R, environment, and threshold stress intensity for environmentally assisted cracking (EAC), K_IEAC. In addition, the environmental influence on fatigue crack growth was examined with the fractographic features and trajectory path, drawn with the limiting values of DK and K_max, DK* and K_max*.

Keywords:
constant amplitude loading, environment, environmentally assisted cracking, fatigue, fractographic features, frequency, stress ratio, trajectory path

Paper ID: JAI12044
DOI: 10.1520/JAI12044

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Author Lee, E Affiliation Naval Air Warfare Center Aircraft Division, Aerospace Materials Division, Code 4.3.4.2, Patuxent River, MD Author Vasudevan, A Affiliation Office of Naval Research, Arlington, VA Title: Environmentally Influenced Fatigue in High Strength Steels Symposium: Fatigue and Fracture Mechanics: 34th Volume, 2003-11-21
Committee: E08 on Fatigue and Fracture