Microstructural investigation of sinter hardened distaloy-DH powder alloys

Abstract

In this study, the effect of sinter hardening on the mechanical properties of Distaloy DH (Fe-2Cu-1.5Mo) powder with 0.4%, 0.6%, and 0,8% graphite additions, was investigated. Powder samples were pressed under 600 MPa, and sintered at 1120°C under endogas from methane for 20 minutes in an industrial sintering furnace. After sintering the samples were cooled with three different cooling rates (0.5oC/sec,1.5oC/sec, and 3oC/sec). Microstructural characterization of samples were done with optical and electron microscopy. Selective etching was utilized in determining the amount of pearlite in samples. The study showed that after sintering a cooling rate of 0.5°C/s led to decreasing amounts of pearlite in all the Distaloy DH samples. With increase in the cooling rates to 3°C/s, Distaloy DH-0.4%C sample contains small amount of pearlite, whereas the alloys Distaloy DH-0.6%C and Distaloy DH-0.8%C led to bainitic and martensitic microstructures.