White layer which is formed on the contact surface between a wire and a die depends on deformation conditions. The aim herein is to obtain the model for the assessment of white layer thickness which is formed in the combined deformational processing by drawing with torsion in high‐carbon 0.7%C steel wire. Finite‐element modelling is used to predict the thickness of the white layer. A series of experiments in the combined deformational processing of high‐carbon steel wire is conducted at different deformational conditions. Using the quantitative coefficient of anisotropy that characterizes the shape of grains, the thickness of white layer is measured. It is found that the theoretical prediction of white layer thickness matches with experimental data. In addition, the mechanical properties of the processed carbon steel wire are studied by the tensile test.