The Effect of Heat Treatment on the Properties of Astaloy Mo and Distaloy Dh Powder Alloys

Abstract

In this study, the effect of heat treatment on the mechanical properties of two prealloyed powders, Astaloy Mo (Fe-1.5Mo) with 2%Cu and 0.6%C additions and Distaloy DH (Fe-2.0Cu-1.5Mo) with 0.6%C addition was investigated. Powder samples were cold pressed under 600 MPa, and sintered at 1120°C in a nitrogen and hydrogen gas mixture for 45 minutes. Sintered sprecimens were then austenitized at 1070°C under nitrogen atmosphere for 20 minutes and then cooled in air (normalized) , quenched in water and tempered at 200C°C for 20 minutes. The transverse rupture strength and hardness values of the sintered and heat treated samples was measured. Microstructure of the samples was characterized with optical microscopy. In comparison to sintered samples, normalizing slightly changed the macrohardness and transverse rupture strength, whereas quenching increased the macrohardness and reduced the transverse rupture strength due to the formation of fully martensitic microstructures. The study showed that in terms of transverse rupture strengths, heat treatment response of Distaloy DH is better than Astaloy Mo alloy of the same composition.