Carbon Control of Cr-Mo Steel by Injection Molding

The effects of carbon (C) addition and debinding temperature on sintering behavior of Cr-Mo steel compacts shaped by metal injection molding were investigated to carry out the control of C content of the sintered compacts. The specimens were made of SCM415 steel powder and additional C powder with polyamide binder. The amount of C addition was varied from 0-0.6 g per 100 g of metal powder. The specimens were debond in air at temperatures ranging from 553-603K for 7.2 ks, and were sintered in argon gas at 1623K for 7.2 ks. The relationship between carbon and oxygen (O) contents of debond compacts vs. those of sintered compacts was analyzed by introducing a parameter, Delta C sub d =C sub d - alpha O sub d (a=C/O atomic weight ratio) which represents the stoichiometric ratio of C and O contents of debound compacts (C sub d and O sub d , respectively). The obtained results showed that the reaction M sub x O+C- > xM+CO (M=Metal element) is dominant for reducing oxides during sintering process and the excess or shortage of C reducing oxides in compact can be estimated successfully by Delta C sub d introduced in this study.