Patent ID: 7923101

Claim:
A cutting tool insert comprising a cemented carbide body and a coating; wherein the cemented carbide body comprises: WC; about 4-12 wt-% Co; and about 5-10 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 0.79-0.90 and a coercivity of about 9-18 kA/m; wherein at least one surface of the cemented carbide body comprises a binder phase enriched surface zone having a thickness of about 5-50 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 1-20 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 texture coefficient TC(0006)≧1.33 (ln h)+2; where: h is the thickness of the α-Al 2 O 3 layer in μm; and texture coefficient TC(0006) is defined as follows: 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: (1012), (1014), (1120), (0006), (1123), and (1126).