The S-N curve for an elastic material is characterized by the Basquin relationship σa= C . Nbf where C is a material constant σa, a is the stress amplitude, Nf is the number of fully reversed stress cycles to failure and b is the Basquin exponent approximately equal to -0.09. When the stress amplitude is equal to the ultimate tensile strength of the material in this alloy, the fatigue life is 1/4 cycle. If a specimen spends 70% of its life subject to alternating stress levels equal to its fatigue endurance limit σe, 20% at l.lσe estimate its fatigue life using the Palmgren-Miner linear damage rule.