Microstructure Development during Sintering of Manganese Alloyed PM Steels

Paper i proceeding, 2009

The microstructure development and its final state after sintering at different temperatures in the case of PM steels based on water atomized manganese alloyed powders was investigated. The effect of manganese alloying method was identified. Fully prealloyed powder show considerable improvement in carbon homogenisation in comparison with specimens of the same chemical composition, admixed with medium carbon ferromanganese. The microstructure development was studied by means of metallography observation of specimens sampled from the furnace at different temperatures during the sintering cycle. First indication of pearlite in the case of admixed system (Fe+0.8wt.Mn[FeMn]) were registered at ~825ºC in comparison with 740ºC for fully prealloyed powder of type Fe-0.8wt.%Mn. Increasing manganese content in the pre-alloyed state leads to further improvement of carbon dissolution and first pearlite formation in powder prealloyed with 1.8wt.%Mn was obtained at ~710ºC. The prealloyed specimens showed more homogeneous and finer microstructure at all temperatures.