The dependence of the hardness of beryllium on grain size

Abstract

The Brinell (BHN) and Rockwell (B and K) hardness have been measured for high-purity polycrystalline beryllium having grain sizes in the range between 90 and 600 microns. For each type of test, the hardness H depends on the average grain diameter ℓ, in accordance with the relationship, H = H 0 + K H ℓ −1 2 , where H 0 and K H are experimental constants. The hardness values are lower than those previously reported for impure material, in agreement with a similar difference in the reported yield stress measurements. Metallographic examination of the indentations showed that considerable plastic flow occurred around them. No cracking was observed.