PENGEMBANGAN MATERIAL TAPAK RODA KERETA API IMPOR DENGAN PENAMBAHAN PADUAN DAN PERLAKUAN PANAS NORMALISASI PENDINGINAN KIPAS

Only train wheels as the train components are all still imported. The necessity these components are quite large at around 30,000 pieces per year, and predicted to increase steadily. According to the Association of American Railroads (AAR) standard, the manufacturing of train wheels can be processed by forging or casting. In Indonesia the most feasible of manufacturing these components are the casting process. This research is applied research that began with the material analysis of imported train wheel and continued with the development of materials and process to create a train wheel prototype. From the hardness results of train wheel track prototype that normalized by cooling fan , obtained 36 HRC of hardness which is higher than the imported train wheel that only 26 HRC of hardness. The Microstructure of train wheel track prototype that normalized by cooling fan are aggregate bainite at the bottom up to 1 mm from the surface, and a very fine pearlite on the inside between 1 mm to 10 mm from the surface. The molybdenum and nickel as bainite promoter causes the formation of aggregate bainite, while the manganese, chromium and copper acts as the partition elements between ferrite and cementite, that inhibit the growth of pearlite resulting in very fine pearlite. Additionally the rapid cooling rate of the cooling fan slow down the diffusion of carbon in austenite, so it tends to produce aggregate bainite in the surface, as well as the very fine pearlite in the inside of the tread of train wheel track prototype that normalized by cooling fan.