Optimizing on Hardening Behavior in Rapidly Solidified Processed Fe-13.5Cr-1.3Mo-0.4C Stainless Steel
Junji IMAI, Tadashi HAMADA, Tokuteru UESUGI, Yorinobu TAKIGAWA and Kenji HIGASHI
Abstract:An effect of the solidification rate on the hardness was investigated in Fe-Cr-Mo-C stainless steel (SUS420J2) produced by rapidly quenched casting process with single-roll at various rolling speeds from 5 to 40m/s. Furthermore the optimizing process to improve hardness after final heat treatment in industrial scale was carried out for the ingot operated with a rolling speed of 10m/s which could exhibit sound state without any materials defaults. A final goal of the higher hardness more than Hv=800 after final heat treatment could be obtained along the process condition with the tempering (baking) treatment (air cooling after heating at 973K for 120s) and the quenching treatment (air cooling after heating at 1323K for 60s). The microstructure observation clarified that the origin of the obtained higher hardness in the optimum processed material compared with the as-cast material resulted from the finer grain size of the old austenite phase at 10μm then 20μm of the as-cast one. Key Words:Stainless steel, Martensite, Hardening, Rapid quench