The Effect of High Cycle Fatigue Damage on Toughness of En8 Grade Steel Part Ii

Fatigue of metals is a subject of practical importance because many components and structures in service are subjected to varying loads and although the average stresses are often low, local concentration of stresses do not reduce the static strength but often lead to failure by fatigue. Micro-crack formation due to fatigue is more in ferritic-pearlitic annealed steel rather than in hardened and tempered steel with a structure consisting of tempered martensite along-with a little bit retained austenite. Fatigue striation density is more at a lower peak stress level as compared to a higher peak stress level fatigue.