About composition, sintering parameters and heat treatments of sinterhardening steels

The work is intended to focus the attention on different aspects of sinterhardening, starting from the main reason to use such a process to the final characterisation of produced samples. Sintehardening allows the production of high apparent hardness parts; the process is rather attractive for components difficult to be quenched because of their dimensions. Admixed alloys, diffusion alloyed mixes, prealloyed ones or hybrid alloys can be used as starting powders, each having positive and negative aspects. Different mix compositions can be used to obtain a sinterhardened structure and, in function of the mix used, there are different sintering parameters and cooling speed to be performed. Properties can undergo sensible changes depending on the quantity of added carbon in the mix. Even though the need of secondary heat treatments may be avoided (and this is one of the main advantages of sinterhardening) it is clear that further treatments (nitriding or nitrocarburising) can only contribute to a sensible increase of surface properties, as it happens for some more traditional steels. This may extend the field of application of sintered parts to highly stressed parts.