Efficient Sintering of Cr-Prealloyed Powders by Careful Adjustment of Process Parameters

Paper in proceeding, 2014

Controlling the surface chemistry during sintering is of paramount importance for the production of PM parts from powders containing oxidation sensitive elements such as Cr. Sintering trials were performed on compacts from water atomized steel powder pre-alloyed with 3 wt.% Cr. Two different compact densities and three different heating rates were investigated in order to evaluate the effect of these process properties in connection with the sintering atmosphere. Using thermal analysis and photoacoustic spectroscopy in combination with results from the fractographic investigations showed that increasing the heating rate up to a certain extent leads to decreased enclosure of surface oxide inside the developing sinter necks. For the samples of higher density the less efficient atmosphere replenishment is responsiblöe for the larger amounts of enclosed Cr-Mn-Si-rich oxides encountered inside the sinter necks. The adjustment of the process parameters in line with the sample density leads to improved mechanical performance.