On Repeated Tension Impact Test of Copper and Brass

Abstract

The authors previously carried out repeated tension impact tests on carbon steels and aluminum alloys by using the universal repeated impact testing machine and Charpy impact testing machine, and clarified the discontinuity of their impact fatigue curves.We have studied, as shown in this paper, about copper and brass under the same tests.Results obtained were as follows:(1) In the diagram of the relation between repeated impact energy and the number of repetition of impacts to failure, two curves come out as shown in Fig. 2, which are found to be discontinuous. As already reported in the previous paper, the specimens fractured, on upper curves, with large scale plastic deformation, whereas on lower curves with true fatigue fracture.(2) Unlike the curves in the previous paper, the curves at N=106 about copper and brass do not show a tendency to lie horizontally.(3) We have found the discontinuous changes of α, β and ψ with impact energy on non-heat treated brass. But every change is not discontinuous on annealed copper and brass.(4) By observating true fatigue fracture of specimens, we have perceived the relation between the radius of arcs of shell patterns and impact energy. When impact energy was near energy of discontinuous point, arcs of shell patterns formed similar concentric circle.