The purpose of the research was to examine the influence of boron on the selected properties of low-alloy cast steels. The chemical compositions of the cast steels were designed especially for this study to contain different alloy elements. The first composition lacked significant alloying elements. The subsequent grades of cast steels had the addition of chrome, chrome with vanadium, and chrome with titanium. It was decided to investigate the influence of boron in the presence of such alloying additives on the temperature of phase transformations. On the basis of dilatometric curves, the characteristic temperatures of the phase transformations were determined. Additionally, to assess the influence of the cooling rate on the structure of cast steels, an analysis of their microstructure, after full annealing and quenching, was carried out.