Effect of heat-and-time treatment on the structure and properties of SCh18, SCh20, SCh25, AChS1 cast irons is established. Metallographic analysis shows that graphite in all cast irons has lamellar structure and occupies the interdendritic space. Investigation of thermomechanical properties of cast irons reveals that the heat-and-time treating technology leads to rise a scale-resistance. The morphology change of formed graphite from vermiculite to nodular during introduction of inoculant into microheterogeneous and microhomogeneous melt results in improvement of mechanical properties.