Microstructural and hardness chara- cterisation of sintered low alloyed steel

Purpose: The purpose of the present study is to produce low ally PM steel without any addition and with addition of ferro-boron addition by conventional PM manufacturing route at the different sintering temperature. Design/methodology/approach: Fe-Ni-Cu-Mo-C sintered steel containing 0.5 percent ferro-boron addition was used in this study. The compacts were prepared by powder metallurgy method involving powder mixing, cold pressing at 700 MPa pressure and sintering at temperatures of 1180, 1200 and 1250°C in nitrogen+% 4 H2 atmosphere for 30 minutes. The influence of sintering temperature and boron addition on the hardness and microstructure of P/M steels were investigated. Optical and scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques were used for characterization of the sintered steels. Findings: The results show that increasing sintering temperature resulted in increase in hardness values; however, those values were dropped after sintering temperature higher than 1180°C. On the other hand, Boron addition contributed to hardness values at sintering temperature of 1200°C. Those values were decreased with increasing sintering temperature. Research limitations/implications: The composition of the sintered steels effect on the density values. The composition of the grain boundaries were affected from sintering temperature. Boron, carbon, molybdenum were seen in the grain boundaries of the specimen having the highest hardness values. It is thought that those compositions strongly effects on hardness values of the specimens. Originality/value: Fe-Ni-Cu-Mo-C base powder with and without boron addition low alloy sintered steel were produced. The effects composition and sintering temperature were investigated.