Fine grained cemented carbide for turning in heat resistant super alloys (HRSA) and stainless steels

摘要

The present invention relates to a cutting insert for turning in heat resistant super alloys and stainless steels comprising a very fine grained hard substrate and a coating. The substrate comprises WC 5-8 wt-% Co and 0.3-1.5 wt-% Cr. Additionally, ppm levels of Ti, Ta, or mixtures of these, are present. The ratio of Me/Co= (at-%Ti+ at-%Nb+at-%Ta)/at-%Co is lower than or equal to 0.014-(CW_Cr)*0.008 and higher than 0.0005. The average sintered WC-grain size is 0.5-0.95 µm and CW_Cr 0.75-0.95. The cemented carbide body is coated with a PVD Ti x Al 1-x N-coating with an average composition of 0.4x0.9 present as single or multilayer coating with a total thickness of 1 µm, but 6.0 µm. racterised in that the substrate comprises WC, 5-8 wt% Co, 0.3-1.5 wt% Cr, and ppm levels of Ta, Ti or mixtures thereof, present in such amounts that the ratio Me/Co=(at-%Ti+at-%Ta)/at-%Cc is lower than or equal to 0.014-(CW_Cr)*0.008 and higher than 0.0005, and CW_Cr is 0.75-0.95, wherein CW_Cr= (magnetic-% Co +1.13*wt-% Cr)/wt-% Co, wherein magnetic-% Co is the weight percentage of magnetic Co, wt-% Cr is the weight percentage of Cr and wt-% Co is the weight percentage of Co in the cemented carbide, and the coating is a PVD Ti x Al 1-x N-coating with an average composition of 0.4x0.9 present as single or multilayer coating with a total thickness of 1 µm, but 6.0 µm.