This paper analyzes the microstructure of gray and nodular cast iron before and after the surface impregnation and their mechanical properties. Final work consists of two parts: theoretical and experimental. In the general (theoretical) part of the final work, the properties and application of iron castings, gray cast iron and nodular cast iron are briefly described. In the experimental part, the mechanical properties of the gray and nodular cast iron were examined and an analysis of their microstructure was made before and after the surface was crushed. The experimental part of the microstructure of gray and nodular cast iron was studied at the Polytechnic Laboratory in Karlovac, while the mechanical properties were tested in the Ljevaonica Karlovac d.o.o .. After the experimental part was carried out, the analysis of the results was made, and it was concluded based on the results obtained