Test specimens were subjected to boro-tempering heat treatment
which combines boronizing with tempering. Pack boronizing
was selected as the boronizing method since the molten salt bath
boronizing technique leaves a salt layer on the specimen, which
reduces the austemperability of ductile cast iron. Boronizing was
performed in a solid medium containing commercial Ekabor-2
powder (the boron donor – B4C, the activator – KBF4 and the filler
– SiC) under atmospheric pressure at a temperature of 900 C for 1,
3 and 5 h. This was followed by quenching in a molten salt bath at
a one of temperatures 250, 300, 350 or 400 C for 1 h. and finally,
air-cooled to room temperature.