Research on New Steelmaking Process for Areo-Engine Bearing steel with Air-melt Bloom Plus Vacuum Remelting

M50Nil, M50 steel are traditional materials which applied for areo-engine bearing serviced in high temperature condition. Double, and sometimes triple, remelting is used to produce consistent steels free of large nonmetallic inclusions for critical applications. New steelmaking processes for M50Nil and M50 were introduced in this research. Continuously casted (CC) bloom with high cleanliness and a targeted chemical composition produced by Basic Oxygen Furnace (BOF)- Ladle Furnace (LF)- Ruhrstahl Heraeus vacuum degassing treatment (RH)-Continuous Casting (CC), instead of high purity iron and alloy were applied as raw material for double vacuum-melt production (VIM-VAR) and single vacuum-melt production (VAR). Steel qualities were compared by testing samples taken from three different process routes, CC+VIM+VAR, CC+VAR and VIM+VAR. The steel quality was compared by testing samples taken from three different process routes, CC+VIM+VAR, CC+VAR and traditional VIM+VAR. The steel cleanliness, carbide size, grain size and mechanical properties were tested on the final forged or rolled bars from the various processes. The main effects and advantages of the three processes including BOF+LF+RH+CC, VIM, and VAR on inclusion size and chemical composition were studied. The carbon emissions were compared between final products made by the new process and those made by the original process. The directions for enhanced manufacture of improved M50NiL and M50 steel were thus indicated.