Patent ID: 8343620

Claim:
A cutting tool insert comprising a cemented carbide body and a coating; wherein the cemented carbide body comprises: WC; about 5-9 wt-% Co; and about 5-11 wt-% cubic carbides of at least one metal selected from the group consisting of groups IVb, Vb and VIb of the periodic table; wherein the cemented carbide body has an S-value of about 0.79-0.9 and a coercivity of about 9-16 kA/m; wherein at least one surface of the cemented carbide body comprises a binder phase enriched surface zone having a thickness of about 5-40 μm and being essentially free from cubic carbides adjacent the coating; wherein the coating comprises at least one α-Al 2 O 3 layer, wherein the α-Al 2 O 3 layer is about 2-9 μm thick and wherein the α-Al 2 O 3 layer comprises columnar grains with a length/width ratio from about 2-12, whereby the α-Al 2 O 3 layer has a (104) texture and a texture coefficient TC(104)≧2.0; where: the texture coefficient TC(hkil) is defined as: TC ⁡ ( hkil ) = I ⁡ ( hkil ) I 0 ⁡ ( hkil ) [ 1 n ⁢ ∑ n = 1 n ⁢ I ⁡ ( hkil ) I 0 ⁡ ( hkil ) ] - 1 where: I(hkil)=measured intensity of the (hkil) reflection; I 0 (hkil)=standard intensity according to JCPDS card no. 46-1212; n=number of reflections used in the calculation where the (hkil) reflections used are: (012), (104), (110), (113) and (116).