May 29-June 3, 2016
It is well recognized that environment has significant effects on the failure of cyclically loaded members/structures Existing experimental data indicates that fatigue life is much shorter in corrosive environment that in more inert environment such as a dry air or vacuum. This paper presents a method and strategy to predict/estimate life under corrosion-fatigue. A corrosion fatigue factor kcorr is defined as the ratio of the fully-reversed stress amplitude in air, (a)air, over that in corrosive environment, (a)corr, for a given fatigue life in terms of a number of cycles to failure, Nf, i.e. kcorr = (a)air/(a)corr at the same Nf. The corrosion fatigue factor resembles the widely used fatigue notch factor kf. The proposed strategy requires the S-N curve in air and the corresponding kcorr factor. Experimental data for three materials, namely 7075-T651, 6161-T561 and 4140 steel tested in laboratory air and 3.5% of NaCl solution were used to illustrate and validate the proposed method. A fairly good agreement is demonstrated in terms of the correlation among air and corrosion-fatigue data.
Daniel Kujawski, "A method for corrosion-fatigue life prediction" in "International Workshop on the Environmental Damage in Structural Materials Under Static Load/Cyclic Loads at Ambient Temperatures", A.K. Vasudevan, Office of Naval Research (retired), USA Ronald Latanision, Exponent, Inc., USA Henry Holroyd, Luxfer, Inc. (retired) Neville Moody, Sandia National Laboratories, USA Eds, ECI Symposium Series, (2016). http://dc.engconfintl.org/edsm/33