Lower compaction pressures and better mechanical properties in heat treated low-alloy sintered steels by performing new infiltration method

One of the main issues of materials produced by powder metallurgy (PM) is the reduction in their strength due to their porous structure. Heat treatment, infiltration, adding alloying elements, and surface engineering methods are some of the main techniques to increase sintered parts strength as well as hardness. In this study, mechanical properties’ improvement of pre-alloyed iron- 1.5% molybdenum powder (Astaloy Mo) by performing copper (Cu) infiltration and heat treatment approaches have been studied. Powders are compacted in dual-action hydraulic press and then sintered in continuous furnace at 1120 ◦C for 25 minutes. Parts with two different densities have been sintered in similar temperature and copper infiltration has been performed on these parts in two different ways. In addition, changing the cooling rate has been performed. Parts have been cooled with two different rates of cooling and changes in their porosity percentage and microstructure have been observed by light optical microscope (LOM) and scanning electron microscope (SEM). Moreover, parts’ hardness has been measured with Vickers hardness test method and under the mentioned techniques, samples have reached to 579.5 HV (equivalent to 2000 MPa in strength).

Keywords:

Astaloy Mo , Infiltration , Heat Treatment , Copper , Powder Metallurgy