Abstract :
Gray cast iron is a good vibration damper or has high damping capacity. It is
generally widely used as an engine base, connecting shaft and heavy equipment.
This research was conducted to investigate the effects of cooling media on the
hardness and microstructure of cast iron. This research was given a heat treatment
with a heating temperature of 900º C, holding time of 20 minutes, then it was cooled
quickly with a variation of the cooling media in the form of oil and water. The
material used is gray cast iron.
The results of gray cast iron hardness test get the lowest hardness value in
raw material of 233,662 BHN and the highest hardness was obtained in water media
quenching of 502, 146 BHN. Therefore, the water media is good to be used as
quenching, because it is easily available, costs effective and can increase the
hardness of material.