Re-Examination of Correlation between Hardness and Tensile Properties by Numerical Analysis

Contact, singular-field, and large-deformation numerical analyses were performed to re-examine the correlation between hardness and tensile properties. Materials have single hardness values, but continuous changes in stress-strain diagrams; it is impossible, in principle, to correlate the hardness to one stress-strain value. Therefore, there must exist an application limit, which is discussed in this study. Because discretization error is unavoidable in such analyses, a method for leveling the discretization error regardless of the analysis condition was introduced. Moreover, in order to generalize the analysis results, the stress-strain diagram used for this analysis was considered as a dimensionless expression in arranging the results. From the analytical results, the following conclusions were deduced. The range in which the empirical equation between hardness and tensile strength is applicable depends on only the value of the work hardening exponent. Moreover, for the 0.05–0.2 range of the work hardening exponent for general steel, the prediction of tensile strength from the hardness is possible with 10% error at indenter face angles between 110° and 136° in case of the wedge indentation.