In recent publications, a new powder-metallurgical processing route was presented that features the blending of carbon-free steel powder with graphite. During a Sinter- or HIP-treatment the latter dissolves and enriches the steel powder with carbon. Using this technique, it is possible to produce stainless martensitic cold work tool steels with > 10 wt.-% Nb that feature a unique microstructure of finely dispersed MX-type niobium carbides within a stainless martensitic matrix. It thus circumvents the well-known problem to produce high-Nb high-C steels that originate in the early precipitation of NbC already in the melt, therefore hindering the atomization of a pre-alloyed powder. This contribution now investigates the development of the microstructure and the formation of NbC for different Nb-rich powders with and without the addition of graphite.
展开▼
