The initiation of fatigue cracks in copper

Abstract

A new sectioning technique has been successfully developed and used to determine the three-dimensional form of the initial fatigue crack in copper. As previously found, intrusions are the earliest form of damage detectable and it has been further shown that their extension is by the formation of tubular holes starting from the surface. This mode of failure is finally superseded by sub-surface irregular microcrack link-up of the slip-band zone cracks and the gross form of crack propagation known as stage II.