Processing of high manganese austenitic sintered steels present several challenges concerning thermodynamic reactions that occur during the sintering of these materials such as Mn oxidation, sublimation and even the formation of liquid phases or undesired compounds, e.g. grain boundary carbides. Therefore it is extremely important to adjust the sintering parameters to obtain the adequate microstructure and properties. In this work, the effect of some sintering parameters, i.e. temperature, gas atmosphere and cooling rate are studied by dilatometry. The experiments revealed that the sintering temperature has small impact on the microstructure formation. On the other hand, the decrease on oxygen chemical potential in the furnace atmosphere resulted in less oxidation of the powder particles. Moreover, the increasing on the cooling rate to 50 °C/min avoided the formation of grain boundary carbides. As a main conclusion, a special sintering cycle for Hadfield steel samples was suggested.
In this work, 17-4PH stainless steel parts processed in a Plasma Assisted Debinding and Sintering (PADS) furnace were characterised in terms of microstructure, final density, microhardness, carbon content and tensile behaviour. To determine whether these properties were satisfactory, the same characterisation procedure was conducted on the parts processed by conventional batch furnaces that are normally employed in Metal Injection Moulding industrial plants. The properties were in good agreement, and only slight differences like an extremely low carbon content (0.003% w/o) were observed. It has been seen that not only economical advances but also intricate materials with suitable responses may be obtained using PADS.