The Effect of Airflow Speed as Cooling Media in the Hardening Process to the Hardness, Corrosion Rate and Fatigue Life of Medium Carbon Steel

Abstract

Carburizing is a method for obtaining a sturdy material surface. This hard surface is used for machine elements that intersect with other materials, so failure due to wear can be avoided. However, this increase in hardness has always been followed by decreased ductility. This condition certainly lowers the fatigue life of the material. For that, it is necessary to compromise between surface hardness and ductility. This study used AISI 1045 steel, which has a surface roughness of 0.4 and 4.7 μm with carburation media used, is a mixture of 80% coconut shell charcoal and 20% Barium carbonate. The sample was given the pack carburization treatment at 850°C and holding time for 3 hours, and then cooled in the open air. The samples were reheated at 850°C, holding time for 17 minutes, and then cooled with airflow at speeds of 10.34, 15.51, and 20.06 m/s for 30 minutes. This research shows that the surface of steel with a roughness of 0.4 μm has excellent performance with the hardness and corrosion level respectively 228.6 HV and 2.3586 mpy at cooling airflow rate of 20.06 m/s while the fatigue life of material occurs at the speed of airflow cooling 10.43 m/s.