On the evaluation of strain inhomogeneity by hardness measurement of formed products

Large plastic deformation of cold formed metal is followed by its hardening, which can be experimentally evaluated by measuring hardness. To convert the measured hardness values into strain, the strain–hardness reference curves are used. Their evaluation is traditionally based on compression tests of cylindrical specimens. New procedure of reference curves evaluation is suggested here, based on an FE simulation of a forming process and direct relation of computed strain and measured hardness. The procedure is illustrated on the example of forward extrusion process and reference curves, obtained by classical and newly suggested procedure are compared.