Generalized Correlation Dependence between the Tensile Strength and Hardness of Steels

Critical analysis of the form of representing correlation between the tensile (ultimate) strength σB and hardness of steels is presented. Simple analytical expressions are derived using statistical analysis, which provide more accurate description of the relationships between Brinell and Rockwell scale hardness values and tensile strength σB. The results of σB calculations by steel hardness using known and developed formulas are compared. The developed formulas are used to analyze changes in σB of carbon steels under the impact of heat treatment. Quantitative evaluations of the effect of quenching and tempering temperatures on the changes in σB values in carbon steels 35, U8, and U10 are based on the results of HRC hardness measurements. The developed formulas can be also used for other steels proceeding from the data on their measured hardness value or reference data presented in literature.