Abstract
A metal thin film doesn't necessarily appear general fatigue behavior like a bulk material. By a balk and film material, there is difference of restricted state because of differing in the number of grains to the direction of film thickness. In this research the diagram of ratio of slipped grains and number of cycle was sorted by film thickness/grain size ratio in carbon steel thin film under cyclic shear loading. Then slip ratio under film thickness/grain size ratio 0.80 saturated. The influence of grain size was considered to slip band formation by examining grain's existence frequency to direction of film thickness. It was bringing close to actual grains by extending two dimensions grain size to three dimensions. As a result, there was the relation between the slip ratio and the grain's cumulate existence frequency in the value whose film thickness/grain size ratio are near 0.9.
