One type of spheroidal cast iron, with additions of 0.51% Cu and 0.72% Ni, was subjected to precipitation hardening. Assuming that the
greatest increase in hardness after the shortest time of ageing is facilitated by chemical homogenisation and fragmentation of cast iron
grain matrix, precipitation hardening after pre-normalisation was executed. Hardness (HB), microhardness (HV), qualitative and
quantitative metalographic (LM, SEM) and X-ray structural (XRD) tests were performed. The acquired result of 13.2% increase in
hardness after ca. 5-hour ageing of pre-normalised cast iron confirmed the assumption.