Sandvik Ab

Per Blomstedt

Marian Mikus

Mikael Lagerqvist

A method of making a cemented carbide body having WC with an average grain size of 0.5-4 &mgr;m, 3.5-9 wt % Co and <2 wt % carbides of Ta, Ti and Nb, and with a substoichiometric carbon content, the method including sintering the body such that an eta phase containing structure is obtained with a size of 1-15 &mgr;m and a content of 10 vol. %-35 vol. %, and subjecting the body to recarburization such that the eta phase in a 50-350 &mgr;m wide intermediate zone is transformed to WC&plus;Co without essentially changing its Co-content.

Method of making cemented carbide body

The present invention relates to a coated body such as a cutting tool insert comprising a wear resistant coating and a cemented carbide body particularly useful for the machining of cast iron parts by turning, milling or drilling at high speeds. The cemented carbide body consists of WC, 3.5-9 wt-% Co and <2 wt-% carbides of Ta, Ti and Nb. It has a core containing finely distributed eta phase islands and an intermediate zone 50-250 &mgr;m thick essentially free of eta phase and with nominal Co content whereby the binder phase in the intermediate zone is present as smaller original islands and larger islands transformed from original eta phase. These latter Co-islands therefore have a size and distribution essentially the same as that of the eta phase in the core. There may be present a thin surface zone free of eta phase with a Co content lower than the nominal Co-content.

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Uppsala, Sweden

Per Blomstedt