On the tensile strength and hardness relation for metals

A method for predicting the ultimate tensile strength (S-u) of a material from Brinell-type hardness tests is described for several metals including steel, aluminum, and copper alloys. The prediction of S-u is based on a consistent relationship between S-u and a material's hardness coefficient, K-d. A simple experimental procedure for determining K-d from indentation-hardness test data is presented. The relationship between S-u and K-d is found to be 1/3 for all cubic metals. Comparisons between predicted and experimentally determined values of S-u are made for each of the materials studied, and sources of error between the two S-u values are discussed.