Surface-coated cutting tool

A surface coated cutting tool comprising:

• a tool substrate and a coating layer on a surface of the tool substrate;
• wherein
• 1) the coating layer has an average thickness in a range of 0.5 μm to 8.0 μm, and the coating layer comprises a lower layer, an intermediate layer, and an upper layer, in sequence from the tool substrate toward the surface of the tool;
• 2) the lower layer has an average thickness in a range of 0.1 μm to 4.0 μm and comprises an A layer having an average composition represented by formula:
• (Al1-xCrx)N, where x is 0.20 to 0.60;
• 3) the intermediate layer has an average thickness in a range of 0.1 μm to 4.0 μm and comprises a B layer having an average composition represented by formula:
• (Al1-a-bCraSib)N, where a is 0.20 to 0.60 and b is 0.01 to 0.20;
• 4) the B layer has a repeated variation in Si level with an average interval of 1 nm to 100 nm between adjacent local maxima and local minima, and satisfies the relation:
• 1.0<Simax/b≤2.0 where Simax is the average of the local maxima of the Si level and the relation:
• 0.0≤Simin/b<1.0 where Simin is the average of the local minima of the Si level;
• 5) the upper layer has an average thickness in a range of 0.1 μm to 4.0 μm and comprises a C layer having an average composition represented by formula:
• (Ti1-α-βSiαWβ)N where α is 0.01 to 0.20 and β is 0.01 to 0.10;
• and
• 6) the C layer has a repeated variation in W level with an average interval of 1 nm to 100 nm between adjacent local maxima and local minima, and satisfies the relation:
• 1.0<Wmax/β≤2.0 where Wmax is the average of the local maxima of the W level and the relation:
• 0.0≤Wmin/β<1.0 where Wmin is the average of the local minima of the W level.