Experimental microhardness for AA 1030, Cu, CuSn7, CuZn30 and 6114 alloys and a correlation with the Hall–Petch relation

In this experimental study, the strip-formed specimens made from aluminum alloy 1030, pure Cu, CuSn7, CuZn30, and low-carbon steel 6114 were cold worked to different ratios. To determine the microhardness values of the materials, microhardness tests were applied. The grain sizes of the materials were determined by the Heyn method, using a metal microscope. The hardness of materials, H, is dependent on the grain diameter, d, in a way similar to the yield stress in the Hall–Petch relation H = H0 + KHd−1/2, where H0 and KH are constants. The microhardness of the materials was found, with reasonable accuracy, to vary with grain size according to the Hall–Petch equation.