Comparison of Fatigue Life of SS-316 & SS-304 due to Rotating bending

Mechanical structures are usually fabricated by using various kinds of metallic materials as the structural components. The structural steels indicate the distinct fatigue limit in the S-N property, in which the S-N curve becomes horizontal and no fatigue fracture occurs at the stress levels lower than this critical level. Thus, mechanical components have been designed to operate well at stress levels lower than the fatigue limit measured at 107 cycles. However, during the last decade, several unexpected failures have been reported even for structural components made of ferrous metals, which were assumed to have a distinct fatigue limit. In recent years, economic and environmental considerations have increased the need to safely extend the service life of mechanical structures such as energy conversion and transportation systems beyond their design life. From this trend, the fatigue behavior of structural materials in the very high cycle regime of 105-107 cycles has become an important subject of research all over the world. In this study, fatigue life between SS-316 and SS-304 is compared. The specimens are subjected to different cyclic load.