Grinding induced machining damage in beryllium

Abstract

An investigation has been made of the machining damage induced in beryllium by surface grinding. A series of damage free specimens was prepared from a bar extruded from a block of hot-pressed beryllium powder. Each specimen was then ground on one large surface using a different set of grinding conditions, as dictated by the requirements of a quarter-replicate factorial experiment which involved eight grinding parameters each taken at two levels. The damage induced by the surface grinding was evaluated by testing each specimen in a four point bending mode. The tests were conducted so that the maximum tensile strain due to bending occurred at the experimentally ground surfaces. A statistical analysis of the results enabled the grinding conditions giving rise to the least and the greatest amount of machining damage to be predicted. In a second series of experiments, these predictions were found to correlate with the metallographically observable damage and the mechanical test data obtained from a further series of bend test specimens.