Prediction of stress-strain curves of elastic-plastic materials based on the Vickers indentation

The Vickers hardness H-v of elastic linear hardened materials with Young's moduli E, yield stresses Y and strain-hardening moduli H is analysed using the finite-element method. The effects of factors affecting the surface profiles of the Vickers indentation are studied. The ratio h(m)/d of the height of the maximum pile-up to the diagonal of the indentation decreases and the ratio r/d of the distance from the centre of the indentation to the maximum pile-up to the diagonal of the indentation increases with increasing H/Y. The value of E/Y, at which h(m)/d takes the maximum value, varies according to the value of H/Y. A method to predict the stress-strain curves of elastic-plastic materials by measuring three factors, that is H-v h(m)/d and r/d, is also proposed. To verify the validity of the proposed method, stress-strain curves of three types of metal are estimated and compared with experimental results. A few kinds of stress-strain curve can be predicted from a set of measured H-V, h(m)/d and r/d. In the case of a linear work-hardened material, the experimental result is located among the predicted results. In the case of a nonlinear work-hardened material, the experimental result within the limits of the plastic strain around 10% is approximately close to the predicted results.