Effect of mechanical alloying and annealing on the sintering behaviour of AstaloyCrL powders with SiC and carbon addition

Alloying is one of the several effective ways of increasing the properties of iron-based PM materials. Modifying the chemical composition of AstaloyCrL powder by silicon addition offers subsequent, effective way of increasing the properties of iron-based PM materials. However, silicon has a high affinity for oxygen, therefore, its implementation is problematic during the sintering process of mixtured powders. In order to overcome this problem and to obtain a homogeneous composition of low-alloy steel with silicon addition, it seems that mechanical alloying (MA) is the most useful process. In order to better understand the sintering behaviour of low-alloy steel modified by silicon, the aim of the present study was to determine the effect of the MA process on AstaloyCrL powder with the addition of silicon in the form of silicon carbide and 0.4/0.6 mass% graphite on the thermal effects during heating measured by differential scanning calorimeter and thermogravimetry techniques. Removal of lubricants during heating of the blended powders as well as exhaust gases from the furnace were monitored by quadruple mass spectrometry. Furthermore, both a light optical microscope and a scanning electron microscope were used for microstructure analysis. Moreover, Thermo-Calc computer software program were used to calculate the enthalpy changes and the volume fraction of phases.