Slip Bands and Other Phenomena at the Early Stages of Fatigue in Copper

Abstract

Annealed copper specimens were fatigued at room temperature in push-pull, and the surface of the specimens was observed through an optical microscope. The main results are as follows : (1) The number of cycles until the appearance of slip bands in cases of low cyclic speeds was smaller than in cases of high cyclic speeds. (2) Slip bands could be observed even at a very small number of cycles, that is, 2×10² cycles at a relatively low stress level as well as higher stress levels, when stressed at low speeds. (3) Fissures develop at least in three ways, to be more precise, they mainly originate from intrusions caused by slip movements, or originate from rows of pits, or originate through co-operation of intrusions and rows of pits.