Abstract
The article is focused on the stress analysis of plane specimens made from hypocutectoid steel, using digital image correlation. It is steel used in the manufacture of railway wheels for freight transport. The aim of the article is to measure the displacement fields by using digital image correlation, from which the strain fields are subsequently calculated. By processing the obtained values using the virtual fields method, the isotropic elastic constants and the hardening behaviour were obtained, which are used to calculate the subsequent stress fields, and they are also used to draw a diagram of engineering and true stress. The maximum average values of stress obtained from true stress-true strain diagram were 990 ± 21 MPa and from engineering diagram 897 ± 18 MPa. The deviation between maximum true and engineering average values of stress was 9 %. The stress fields obtained for 25 and 58 % strains are illustrated in the article.

Key words
digital image correlation, virtual fields method, true stress-true strain diagram, engineering diagram

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