Surface-coated cubic boron nitride sintered material tool

A surface-coated cubic boron nitride sintered material tool comprising:

• a tool body which is made of a cubic boron nitride sintered material;
• and
• a hard coating layer formed on a surface of the tool body, the hard coating layer being made of an alternate laminated structure, in which at least one A layer and at least one B layer are alternately laminated, and having a total layer thickness of 0.7 to 4.0 μm,
• wherein (a) the cubic boron nitride sintered material has a composition including:
• 10 to 50 vol % of one or more of TiC, TiN, and TiCN;
• 0.1 to 2 vol % of WC;
• 0.3 to 5 vol % of A1N;
• 2 to 10 vol % of TiB2;
• 1.5 to 10 vol % of Al2O3;
• and
• 30 to 80 vol % of cBN (cubic boron nitride),
• (b) the A layer is a Ti and Al complex nitride layer, which has an average single layer thickness of 0.1 to 3.0 μm and has an average composition satisfying 0.4≤x≤0.7 (x represents a content ratio of Al in terms of atomic ratio) in a case where the A layer is represented by a composition formula (Ti1-xAlx)N,
• (c) the B layer is a Cr, Al and M complex nitride layer, which has an average single layer thickness of 0.6 to 3.0 μm and has an average composition satisfying 0.03≤y≤0.4 and 0≤z≤0.05 (y represents a content ratio of Al in terms of atomic ratio, z represents a total content ratio of the component M in terms of atomic ratio, and the component M represents one or more elements selected from group 4a elements excluding Cr, group 5a elements, group 6a elements, B and Si in the periodic table) in a case where the B layer is represented by a composition formula (Cr1-y-zAlyMz)N, and
• (d) a hardness of the B layer obtained by performing a nano-indentation test with a load set such that an indentation depth is 1/10 or less of the layer thickness is in a range of 28 to 40 GPa, and a value of a plastic deformation work ratio Wplast/(Wplast+Welast) is in a range of 0.35 to 0.50.