Pengaruh Proses Austempering Pada Temperatur Konstan 300 ºC Selama 30 Menit Terhadap Struktur Mikro Dan Ketangguhan Besi Cor Nodular

This research was conducted to determine the effect of the austempering process at a temperature of 300 ºC for 30 minutes on the microstructure and toughness of nodular cast iron. The austempering process begins with austenization at a temperature of 850 ºC for 60 minutes, then the quenching process is carried out in a salt bath until a temperature of 300 ºC is held for 30 minutes and then cooled to room temperature. In microstructure testing (SEM) on the raw material there is a ferrite phase with a light color, coarse pearlite is gray, and graphite is black. After the austempering process, fine pearlite and graphite phases appear with a smaller size than the raw material. Where pearlite phase is gray and graphite is black. The results of the charpy method of impact testing on raw materials obtained an impact value of 0.06375 Joule/mm2. After the austempering process was carried out, the impact price decreased to 0.05 Joule/mm2. This is because some of the graphite will combine with ferrite to form cementite, so that the ferrite mixes with pearlite and the size of the graphite becomes smaller so that the toughness value decreases