Processing of P/M M2 high speed steels by mould casting using thermosetting binders

This communication presents a modified powder injection moulding (PIM) method for M2 tool steel powder using a new binder system based on a thermosetting resin. The moulding is carried out at room temperature by pouring directly the slurry (resin and tool steel previously mixed) in the mould. Afterwards, the mould is heated at the curing temperature of the resin. We have optimised the powder–binder formulations and the best thermal debinding cycle were determined by means of thermogravimetric analysis (TGA). The presence of carbon in the brown parts seems to be necessary in order to sinter the specimen. Moreover, the sintering temperature range can be extended to more than 100°C, being able to achieve very high density at 1100°C, by means of incomplete debinding. The microstructural study of sintered parts revealed the coarsening of the carbides with the temperature. Besides M6C carbide that appears during all the temperature range studied, M23C6, M2C and M4C3 carbides sequentially appear with the sintering temperature.