This work enriches the fundamental process knowledge of ductile iron heat treatment to create efficiently perferritic (IDI) and ausferritic ductile cast irons (ADI). In-situ neutron diffraction allows characterizing the influence of the alloying element molybdenum on the ADI phase transition kinetics. In addition, the applicability of various kinetic models and the microstructure are investigated in detail. IDI presents itself as a cost-effective alternative to ADI and its phase transitions are characterized accordingly. Finally, the knowledge obtained supports designing a fatigue-resistant ADI alloy with regard to energy efficient manufacturing process.