| 摘要 |
The present invention relates to a coated cemented carbide insert for turning of steel, like low alloyed steels, carbon steels and tough hardened steels at high cutting speeds. The cemented carbide consists of WC, 2-10 wt-% Co and 4-12 wt-% of cubic carbides of metals from groups IVa, Va or VIa of the periodic table, preferably Ti, Ta and Nb. The Co-binder phase is highly alloyed with W with a CW-ratio of 0.75-0.90. The insert has a binder phase enriched and essentially cubic carbide free surface zone A of a thickness of <20 mu m and along a line C, essentially bisecting the edge, in the direction from the edge to the centre of the insert, a binder phase content increases essentially monotonously until it reaches the bulk composition. The binder phase content at the edge in vol-% is 0.65-0.75 times the binder phase content of the bulk and the depth of the binder phase depletion is 100-300 mu m, preferably 150-250 mu m. The insert is coated with 3-12 mu m columnar TiCN-layer followed by a 2-12 mu m thick Al2O3-layer. |
