Fractographic Study on the Fatigue Failure Surfaces of Heat-Treated and Shot Peened EN- 8 Steel (080M40/AISI 1040)

Abstract

The microstructure study has been carried out on the fatigue fractured surface of heat-treated and shot peened EN-8 (080M40/AISI 1040) steel. This microstructure study has revealed the characteristic appearance and physical arrangement of a metal as observed with a microscope. In order to realize the initiation and progression of fatigue failure, the fractured surfaces have been analyzed with the Scanning Electron Microscope (SEM). In this present work, the different categories of heat-treated and shot-peened fatigue fractured samples such as WT, Q&T, SP, and combined Q&T and SP have been taken for fractographic investigation. For probing the fractured surface, SEM images have been taken with different magnifications for each category of samples fractured under 293.45MPa bending stress. The combined Q&T and SP sample has fractured at the interface of a granular region and beach marks have been spread over the fractured surface. The results of Q&T and SP sample fractured surface analysis have concluded that the brittle fracture with inter-granular cracks has been formed due to the relieving of residual stresses at the surface of the samples obtained from combined treatments.