Fatigue damage initiation mechanism in carbon steel thin film under cyclic in-plane pure shear loading

Abstract

Metal thin films don’t necessarily appear general fatigue behavior like a bulk materials. Comparing thin films and bulk materials, since the number of grains of the film thickness direction is different, restricted condition is different. Some studies of axial direction and bending direction loading have been reported, but few studies of in-plane pure shear loading have been reported. In this study, using acryl bar pasted carbon steel film, fatigue test was performed under cyclic in-plane pure shear loading. And about deference of slip band formation factor and crack initiation factor, examination was performed by varying to change carbon content, film thickness and average grain size. As a result, two relations about fatigue behavior were found. Slip ratio was influenced by film thickness / grain size ratio. But crack ratio was influenced by pearlite volume ratio. Therefore, for the carbon steel thin film behavior of slip band and crack initiation are considered to be result of different factors.

Keywords

• fatigue
• carbon steel film
• cyclic in-plane pure shear
• shear deformation
• slip band
• crack