Answer :

Solution :

Surface roughness increases surface matches and hence these is more concentration of stresses during fatigue loading and hence improving surface finish will result in less cracks and enhanced surface finish.

Shot peening is a method of improving fatigue stress by inducing compressive stresses which decreases chances of crack and this cold working technique increases the fatigue strength of material.

Decreasing relative humidity will decrease the moisture content and hence chances of corrosion in less. Corrosion decreases fatigue strength by degrading the material.