ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 28 February 2005
Page Count: 13

Environmentally Influenced Fatigue in High Strength Steels

Lee, EU
Materials Engineer, Naval Air Warfare Center Aircraft Division, Aerospace Materials Division, Patuxent River, MD

Vasudevan, AK
Scientific Officer, Office of Naval Research, Arlington, VA

(Received 30 October 2003; accepted 26 April 2004)

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, ΔK, 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 ΔK and K_max, ΔK* and K_max*.

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

Paper ID: JAI12044
DOI: 10.1520/JAI12044
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