CN101088759B - Coat cutting tool blade - Google Patents

Abstract

The present invention relates to a CVD coating cutting tool blade, which is provided with a modified toughness capacity, the toughness capacity is provided with a faculty of enduring the high temperature, and it not sacrifice the security of the blade. The blade coating includes a TiCxNy layer, which is provided with a low drawing stress level from 50 to 500 MPa, and an alpha-Al2O3 layer, the alpha-Al2O3 layer is provided with a high surface flatness that the average Ra is less than 0.12 mu m measured by the AFM technology, wherein the layer is obtained by overpowering wet abrasive blasting operation to the coating.

Description

Coated cutting tool insert

Technical field

The present invention relates to a kind of high-performance coating coated cutting tool, it is particularly useful for being polished to turning low-alloy steel in the rough machined scope, carbon steel and tough and tensile hardened steel with high cutting speed under dried wet condition, and have the ability that stands high temperature, and do not sacrifice the blade security.This blade based on WC, cubic carbide and cobalt binder mutually, and rich cobalt surf zone provides good plasticity_resistant deformation and high tenacity performance for cutting tip.In addition, coating comprises a plurality of wearing layers, and this wearing layer is through surperficial post processing, thereby provides surprising improvement cutting ability for tool blade.

Background technology

Current cutting element major part is based on carbide chip, and this carbide chip scribbles some solid beds, as TiC, TiC _xN _y, TiN, TiC _xN _yO ₂And Al ₂O ₃Careful order and the thickness of selecting each coating is to be fit to different cutting application and workpiece materials.The coating technology of frequent employing is chemical vapor deposition (CVD) and physical vapor deposition (PVD).The CVD coated chip especially has the very big advantage that surpasses no coated chip aspect anti-flank wear and the anti-crescent hollow abrasion.

The CVD technology is in quite high temperature range, carries out in 950-1050 ℃.Because the mismatch in coefficient of thermal expansion between this temperature high deposition and coating deposited material and the sintered-carbide tool blade is so CVD may cause coating to have cooling crack and high tensile stress (sometimes up to 1000MPa).High tensile stress may be disadvantageous under some machining conditions, and its reason is that this can make cooling crack extend further to cemented carbide body and makes cutting edge fracture.

In the metal cutting industry, make great efforts to improve machining condition environment (envelope) always, promptly do not sacrificing the ability that under the situation of anti-breaking capacity during the interruption slow cutting or anti-smear metal ability, stands higher cutting speed.

Realize important improvement in the applied environment by the more thick coating that makes blade be combined with rich bonding phase surface zone and to optimize.

Yet, if increase coating layer thickness, the positive effect on the wearability will be by the counter productive that increases disequilibrium, the form of this counter productive is for the risk that is coated with delamination layer that increases and reduce toughness and make cutting element more unreliable.This is particularly useful for softer workpiece material, such as mild steel and stainless steel and when coating layer thickness surpasses 5-10 μ m.In addition, thick coating has more uneven surface usually, and when cutting as mild steel and stainless smearing (smearing) material, it will become negative characteristics.Come coating is carried out the back smooth treatment by brushing or wet abrasive blasting, to use remedial measure, this is disclosed in a plurality of patents, and for example EP 0 298 729, among EP1 306 150 and the EP 0 736 615.For example, at US 5,861, in 210, its purpose is for obtaining smooth cutting edge, and with Al ₂O ₃Expose,, thereby TiN is retained on the clearance side, as the abrasion detection layer as the outermost layer on the rake face.Obtained the coating of high spalling resistance.

The post-processing technology of every kind of exposed surface for example is exposed to coating surface the mechanical shock of for example wet abrasive blasting or dry blasting, all will produce some influences to the surface smoothness of coating and the stress state of coating (α).

The tensile stress that can reduce in the CVD coating is impacted in strong sandblast, but usually will be with because to lose coating surface fineness along cooling crack formation groove be cost, perhaps even can cause being coated with delamination layer.

Very strong processing in addition may will make stress state big change takes place, for example, change into height pressure from high tension, disclosed as EP-A-1 311 712, in this patent, used the dry blasting technology.

Find surprisingly now, make up some carbide alloy substrate synthetic and some coating structure and thickness, and the coated cutting tool that utilizes wet abrasive blasting to carry out post processing under controlled conditions obtains good cutting performance on the range of application wideer than prior art coated cutting tool.

Cobalt binder and W height alloy.W content in boning mutually can be expressed as CW-ratio:

CM-ratio＝M _s/(wt-％Co×0.0161)

Wherein, M _sThe saturation magnetization that measures, unit is hAm ²/ kg; And wt-%Co is the cobalt content in the carbide alloy.Low CW-ratio is equivalent to the high W content of cobalt binder in mutually.The post processing of being adopted will provide favourable tensile stress level for coating, be Al ₂O ₃Layer provides some important crystalline characteristics, and provides good surface smoothness for top surface.

Above-mentioned and combination sandblast technology has enlarged the restriction of the coating layer thickness that can apply effectively, and does not have mis-behave.Therefore, the present invention has the application of non-constant width now.To tenacity properties and the bonding remarkable improvement of coating will be surprising.

In order to change the stress state of coating significantly by sandblast, blast media (Al for example ₂O ₃Gravel) must HI high impact ground bump coating surface.Impulsive force can be by following condition control, for example angle of shock of the concentration of the granularity of the distance between spray pressure (wet abrasive blasting), sandblast jet pipe and the coating surface, blast media, blast media and sandblast stream.

Summary of the invention

The purpose of this invention is to provide a kind of CVD coated tool blade, this CVD coated tool blade has the toughness performance of improvement, and this toughness performance has the ability that stands high temperature, and does not sacrifice blade security or toughness.

Description of drawings

Fig. 1 illustrates the angular instrument device that is used for the residual stress that estimates by the X-ray measurement, wherein

E=Euler 1/4 support

The S=sample

I=incident X-ray bundle

D=diffraction X-ray bundle

θ=angle of diffraction

ω＝θ

ψ=along the inclination angle of Euler's 1/4 support

Φ=around the anglec of rotation of sample axis

The specific embodiment

Therefore, the present invention relates to a kind of coated cutting tool insert, this coated cutting tool insert comprises polygon or circular main body substantially, and this main body has at least one rake face and at least one clearance plane, comprises coating and carbide substrate.The composition of this main body is 4.4-6.6, be preferably 5.0-6.0, most preferably be the Co of 5.0-5.8wt-%, the cubic carbide of 4-8.5wt-%, the WC of surplus, the WC of preferred 85-91wt-%, most preferably be the WC of 87-90wt-%, preferably, average grain size is 1-4 μ m, CW-ratio is in the 0.78-0.92 scope, and surf zone is made up of cubic carbide TiC, TaC and/or NbC.

The thickness of the described surf zone of being made up of cubic carbide is for from 10 μ m, and is perhaps optional from 20 μ m perhaps from 15 μ m, to 40 μ m, perhaps to 35 μ m, perhaps to 30 μ m, perhaps optional to 25 μ m.

Coating comprises at least one TiC _xN _yLayer and 100% a α-Al ₂O ₃Good crystalline layer (well crystalline layer).A this α-Al ₂O ₃Layer be on the rake face and along the outermost visible layer of cutting edge line, and this outermost visible layer can utilize enough high-energy to carry out the processing of wet abrasive blasting consumingly, with at Al ₂O ₃And TiC _xN _yThe tensile stress relaxation that produces in the layer.Al ₂O ₃The outermost layer smear metal contact zone on rake face at least has very smooth surface.

Find surprisingly, if polygon or circular coated cutting tool insert have at least one rake face and at least one clearance plane substantially, then can realize the toughness performance significantly improved, described blade is coated to small part, and is fabricated to and has following feature:

The TiC of inferior end layer _xN _yThe thickness of layer is from 3 μ m, preferably from 4 μ m, more preferably from 5 μ m, most preferably from 6 μ m, to 15 μ m, preferably to 13 μ m, most preferably to 10 μ m, x 〉=0 wherein, y 〉=0 and x+y=1, and preferably make by MTCVD, and tensile stress is 50-500MPa, be preferably 50-450MPa, most preferably be 50-400Mpa; With

Outside α-Al ₂O ₃Layer, its thickness is from 3 μ m, preferably from 3.5 μ m, most preferably from 4 μ m, to 12 μ m, preferably to 11 μ m, most preferably to 10 μ m, it is the outermost layer on the rake face, and along edge line, it has average roughness Ra＜0.12 μ m at least on the smear metal contact zone of rake face, be preferably≤0.10 μ m, this mean roughness utilizes AFM (AFM) to measure on the zone of 10 μ m * 10 μ m, and the XRD diffracted intensity ratio of I (012)/I (024) (peak height value subtracting background value) 〉=1.3, be preferably 〉=1.5.

Preferably, at TiC _xN _yLayer and α-Al ₂O ₃Having thickness between the layer is the TiC of 0.2-2 μ m _xN _yO _zBinder course, x 〉=0, z＞0, and y 〉=0.This two-layer gross thickness≤25 μ m.

In addition, according to the present invention, extra play can be introduced in the coating structure between substrate and the above-mentioned layer, and this extra play is made up of the metal nitride that is selected from following metal and/or carbide and/or oxide: Ti, Nb, Hf, V, Ta, Mo, Zr, Cr, W and Al, always coating layer thickness＜5 μ m.

Preferably, at TiC _xN _yKeep some tensile stresses in the layer, it is former because find during machining aspect the occurrence temperature rising, and is stable when this compression stress of bringing out still has tensile stress unlike coating.Also find,, then need very high sandblast impulsive force, under this condition, peeling off of coating often taken place along cutting edge if compression stress is brought out by sandblast.

Inner TiC _xN _yThe residual stress σ of layer measures, utilizes known sin by XRD ²The ψ method determines that this method is described in I.C.Noyan, in Residual Stress Measurementby Diffraction and Interpretation one literary composition of J.B.Cohen (Springer-Verlag, New York, 1987 (pp117-130)).By using angular instrument device as shown in Figure 1, utilize TiC _xN _y(422) CuK in the reflection _αRadiation is measured.Measuring on the even curface as far as possible.Recommend to use the laterally inclined technology (how much of ψ) with six to 11 ψ angles, this angle is at the sin of 0-0.5 ²ψ scope equidistant (ψ=45 °).Further preferably, the equidistant Φ angle of distributing in 90 ° Φ is fan-shaped.In order to confirm the biaxial stress state, sample should tilt with Φ=0 ° and 90 ° of rotations and with ψ.Recommend research the possibility of shear stress to occur, thereby measure negative ψ angle and positive ψ angle.Under the situation of Euler's 1/4 support, finish by measuring sample in Φ=180 ° with 270 ° the time for different ψ angles.Sin ²The ψ method is used for preferably utilizing some business softwares that residual stress is estimated, software is such as Bruker AXS DIFFAC ^PlusStress32 v.1.04, wherein Young's modulus is constant, E=480Gpa, (C, N) layer time is v=0.20, utilizes the Pseudo-Voigt-Fit function that reflection is positioned and Poisson's ratio is at MTCVD Ti.In following situation, use following parameter: E modulus=480Gpa, and Poisson's ratio v=0.20.In the situation of biaxial stress state, tensile stress is calculated as the mean value of the biaxial stress that is obtained.

For α-Al ₂O ₃, since required high 2 θ angle XRD reflection usually too a little less than, so can not use sin usually ²The ψ technology.Yet, found useful optional measure, this measure makes α-Al ₂O ₃State relevant with cutting ability.

For α-Al ₂O ₃Powder, diffracted intensity than I (012)/I (024) near 1.5.PowderDiffraction File JCPDS No 43-1484 stipulates I ₀(012)=72, I ₀(024)=48.For (the σ CVD α-Al approximately＞350Mpa) of the tensile stress on the carbide alloy ₂O ₃Layer, strength ratio I (012)/I (024) significantly less than desired value 1.5, is generally surprisingly most＜and 1.This may be because by some unordered (disorder) in the lattice that tensile stress caused.Have been found that when for example discharging the stress of this layer, if perhaps this layer is removed and by efflorescence, then this ratio I (012)/I (024) will be more approaching, equal or even greater than 1.5 from substrate fully by strong sandblast operation.The big more height of the sandblast power that is applied, this ratio also will be big more.Therefore, this strength ratio can be used as α-Al ₂O ₃The important state feature of layer.

According to the present invention, coated cutting tool has the CVD coating, and this CVD coating comprises the TiC of layer second from the bottom _xN _yLayer and outside α-Al ₂O ₃Layer.This Al ₂O ₃Can make according to patent EP 603 144, it is Al ₂O ₃Layer provides the crystallization texture of 012 direction, texture coefficient T C (012)＞1.3, and perhaps make according to patent US 5,851,687 and US 5,702,808 preferred＞1.5, and it provides along the texture of 110 directions, texture coefficient T C (110)＞1.5.In order to obtain high surface flatness and low tensile stress level, coating is carried out the wet abrasive blasting operation, wherein, whitewash in water by Al ₂O ₃F150 granularity (FEPA standard) form, air pressure is 2.2-2.6bar, the time is 10-20 second/blade.Spray gun is arranged to from the about 100mm of blade, and becomes 90 ° spray angle.This blade has the color different with the rake face of black in clearance side.Preferably, depositing TiN (yellow), TiC _xN _y(grey or bronze colour), ZrC _xN _yThe thickness of the outermost of (blush or bronze colour) is the color layer of 0.1-2 μ m, x 〉=0 wherein, and y 〉=0 and x+y=1, perhaps preferably, depositing Ti C (grey).Then, this blade is carried out sandblast, thereby remove top layer, to expose the Al of black ₂O ₃Layer.Coating on the rake face will have low required tensile stress 50-500Mpa, and this clearance side will have high tensile stress, scope is 500-700Mpa, according to the selection of coating and the thermal coefficient of expansion of employed carbide chip (CTE), the tensile stress on the rake face is lower than the tensile stress on the clearance plane.In another embodiment of the present invention, on rake face and clearance side, coated chip is carried out sandblast, and colored heat-resisting enamelled coating is sprayed on the clearance side, perhaps Cai Se PVD layer is deposited on this place, so that acquisition can be recognized the ability of used cutting edge.

Example 1

Prepare following sample:

A) carbide cutting blade, composition: 5.5wt-%Co, 2.9wt-%TaC, 0.5wt-%NbC, 1.4wt-%TiC, 0.9wt-%TiN, surplus WC, average grain size are about 2 μ m, and surf zone is made up of cubic carbide, thickness is 29 μ m.

B) carbide cutting blade, composition: 5.5wt-%Co, 2.9wt-%TaC, 0.5wt-%NbC, 1.9wt-%TiC, 0.4wt-%TiN, surplus WC, average grain size are about 2 μ m, and surf zone is made up of cubic carbide, and thickness is 18 μ m.

C) carbide cutting blade, composition: 5.5wt-%Co, 2.9wt-%TaC, 0.5wt-%NbC, 1.6wt-%TiC, 0.7wt-%TiN, surplus WC, average grain size are about 2 μ m, and surf zone is made up of cubic carbide, and thickness is 23 μ m.

Measurement A)-C) saturation magnetization M _sBe 0.077hAm ²/ kg, CW-ratio are 0.87.With A)-C) blade utilizes traditional CVD technology to apply the thick TiN layers of 0.5 μ m at 930 ℃, utilizes the MTCVD technology then, uses TiCl ₄, H ₂, N ₂And CH ₃CN applies the thick TiC of 7 μ m as handling gas at 885 ℃ _xN _yLayer.In the treatment step subsequently in same coating cycle, utilize TiCl ₄, CO and H ₂, be approximately the thick TiC of 0.5 μ m 1000 ℃ of depositions _xO _zLayer is then at the thick α-Al of deposition 7 μ m ₂O ₃Before, utilize 2%CO ₂, 3.2%HCl and 94.8%H ₂Mixture flushing reactor started Al in 2 minutes ₂O ₃Handle.Deposit the TiN layer of about 0.5 μ m at the top.Process conditions during the deposition step are as follows:

	TiN	TiC xN y	TiCxO z	Al 2O 3Start	Al 2O 3
						Step	1 and 6	2	3	4	5
TiCl 4	1.5％	1.4％	2％
						N 2	38％	38％
CO 2				2％	4％
						CO			6％
AlCl 3					3.2％
						H 2S	-				0.3％
HCl				3.2％	3.2％
						H 2	Surplus	Surplus	Surplus	Surplus	Surplus
CH 3CN	-	0.6％
						Pressure	160mbar	60mbar	60mbar	60mbar	70mbar
Temperature	930℃	885℃	1000℃	1000℃	1000℃
						Time	30min	4.5h	20min	2min	7h

Extra blade is:

D) with A) carbide cutting blade that type is identical, its difference only is: TiC _xN _yLayer and α-Al ₂O ₃The thickness of layer, its thickness is respectively 6 μ m and 10 μ m are thick, utilizes identical process conditions to make, except TiC _xN _yAnd Al ₂O ₃Sedimentation time is respectively 4h and 10h.

E) with B) carbide cutting blade that type is identical, its difference only is: TiC _xN _yLayer and α-Al ₂O ₃The thickness of layer is respectively 6 μ m and 10 μ m, utilizes identical process conditions to make, except TiC _xN _yAnd Al ₂O ₃Sedimentation time is respectively 4h and 10h.

F) with C) carbide cutting blade that type is identical, its difference only is: TiC _xN _yLayer and α-Al ₂O ₃The thickness of layer is respectively 6 μ m and 10 μ m, utilizes identical process conditions to make, except TiC _xN _yAnd Al ₂O ₃Sedimentation time is respectively 4h and 10h.

According to A)-Al of the deposition of F) blade ₂O ₃The XRD analysis of layer shows: it is only by the α phase composition, and texture coefficient T C (012)=1.6, and it is as to give a definition:

$\mathrm{TC}\left(012\right)=\frac{I\left(012\right)}{I_0\left(012\right)}{\left\{\frac{1}{n}\mathrm{\Σ}\frac{I\left(\mathrm{hk}1\right)}{I_0\left(\mathrm{hk}1\right)}\right\}}^{-1}$

Wherein

The tested intensity of I (hk1)=(hk1) reflection

I ₀(hk1)=normal intensity of Powder Diffraction File JCPDS No 43-1484

N=calculates employed reflection number in (hk1) reflection: (012), (104), (110), (113), (024), (116).

According to A)-F) coated chip carries out post processing by aforesaid blasting method, utilize 2.4bar blasting pressure and open-assembly time 20 seconds blade rake face carry out sandblast.

The smoothness of coating surface is expressed as known roughness value Ra, and the AFM that is used on the equipment of SurfaceImgaing System AG (SIS) measures.Ten plane surfaces of selecting at random (10 μ m * 10 μ m) in the smear metal contact zone on rake face are gone up and are measured roughness.The mean value MRa that is drawn from these ten Ra values is 0.11 μ m.

Adopt Siemens D5000, the Bragg-Brentano diffractometer carries out X light diffracting analysis, is used to utilize Cu K α radiation to determine I (012)/I (024) ratio.

The I that is obtained (012) on the clearance side/I (024) ratio is about 1.4.Corresponding measurement on the rake face shows: the I that is obtained (012)/I (024) ratio is about 2.2.

Utilize the ψ on the X-ray diffractometer Bruker D8 Discover-GADDS to determine residual stress how much, this X-ray diffractometer is equipped with laser video location Euler 1/4-support rotary anode as X source (CuK α radiation) and regionally detecting device (Hi-star).The pointing instrumentation that is of a size of 0.5mm is used for focused beam.Utilize goniometer be provided with 2 θ=126 °, ω=63 °, Φ=0 °, 90 °, 180 °, 270 °, carry out TiC _xN _y(422) Fan She analysis for each Φ angle, is carried out eight inclinations of ψ between 0 ° and 70 °.Sin ²The ψ method is used to utilize the DIFFAC of software Bruker AXS ^PlusV.1.04, Stress32 estimates residual stress, and wherein Young's modulus is constant, and E=480Gpa, and Poisson's ratio v=0.20 utilize the Pseudo-Voigt-Fit function that reflection is positioned.Confirm the biaxial stress state, and mean value is used as residual-stress value.On rake face and clearance side, measure.For according to A)-F) blade, the tensile stress that is obtained on the clearance side is about 630Mpa.Corresponding measurement on the rake face shows: for according to A)-C) blade, obtain to be approximately the tensile stress of 370MPa, for according to D)-F) blade, obtain to be approximately the tensile stress of 390MPa.

Example 2

The blade A of test sample 1), and with commercially available not sandblast blade (the high-performance blade in the P15 zone) carry out comparing about the toughness in the vertical turning operation that is interrupted cutting.

Material: charcoal steel SS1312

The cutting data:

Cutting speed=120m/min

Cutting depth=1.5mm

Feeding=begin to be 0.15mm, the speed with 0.08mm/min increases gradually, ruptures up to blade

Test 10 blades of each modification

Blade type: CNMG120408-PM

The result:

Average feeding during fracture

Commercially available blade 0.244mm/rev

The blade A of example 1) 0.275mm/rev

Example 3

The blade D of test sample 1), and with commercially available blade carry out comparing about the toughness in the vertical turning operation that is interrupted cutting similar in appearance to example 2.

Material: charcoal steel SS1312

The cutting data:

Cutting speed=140m/min

Cutting depth=1.5mm

Feeding=begin to be 0.15mm, the speed with 0.08mm/min increases gradually, ruptures up to blade

Test 10 blades of each modification

Blade type: CNMG120408-PM

The result:

Average feeding during fracture

Commercially available blade 0.232mm/rev

The blade D of example 1) 0.315mm/rev

Example 4

And carry out about the tolerance total plastic property in the oriented manipulation of SS2541 distortion with commercially available blade and compare the blade A of test sample 1), similar in appearance to example 2.

The cutting data:

Cutting speed=220m/min

Feed speed=0.35mm/rev

Cutting depth=2mm

Life tools standard: outside of belly wearing and tearing 〉=0.5mm

The result:

Reach required process-cycle number life tools

Commercially available blade 65

The blade A of example 1) 85

Example 5

The blade A of test sample 1), and with commercially available blade carry out comparing about tolerance plastic deformation in the turning of SS2544-05 near blade similar in appearance to example 2.

The cutting data:

Cutting speed=200m/min

Feed speed=0.35mm/rev

Cutting depth=2.5mm

Life tools standard: outside of belly wearing and tearing 〉=0.4mm

The result:

Reach required process-cycle number life tools

Commercially available blade 19

The blade A of example 1) 27*

* test blade A) stops after 27 cycles in advance, and does not still reach standard life tools that is limited.

Example 3-5 shows the blade A according to example 1 of the present invention) and D) show extraordinary tolerance plastic deformation and better toughness characteristic than blade according to prior art.

Example 6

The blade B of test sample 1), E C)) and F), and carry out comparing about the toughness in the vertical turning operation that is interrupted cutting with commercially available blade similar in appearance to example 2.

Material: charcoal steel SS1312

The cutting data:

Cutting speed=150m/min

Cutting depth=1.5mm

Feeding=begin to be 0.15mm, the speed with 0.08mm/min increases gradually, ruptures up to blade

Test 10 blades of each modification

Blade type: CNMG120408-PM

The result:

	Average feeding (mm/rev) during fracture
		Commercially available blade	0.206
B)	0.270
		C)	0.259
E)	0.230
		F)	0.216

Example 7

The blade B of test sample 1) and C), and with commercially available blade carry out comparing about the anti-total plastic property distortion in shaving (facing) operation of SS2541 similar in appearance to example 2.

The cutting data:

Cutting speed=200m/min

Feed speed=0.35mm/rev

Cutting depth=2mm

Life tools standard: outside of belly wearing and tearing 〉=0.5mm

Blade type: CNMG120408-PM

The result:

	Reach required process-cycle number life tools
		Commercially available blade	59.5
B)	61
		C)	63

Example 8

The blade B of test sample 1), E C)) and F), and carry out comparing about the tolerance total plastic property distortion in the shaving operation of SS2541 with commercially available blade similar in appearance to example 2.Test comprises two kinds of different blade size, is represented as two kinds of different blade types: CNMG160612-PR (cutting edge length=16mm) and CNMG190612-PR (cutting edge length=19mm).

The cutting data:

Cutting speed=220m/min

Feed speed=0.35mm/rev

Cutting depth=3mm

Life tools standard: outside of belly wearing and tearing 〉=0.5mm

The result:

Claims (15)

1. the coated cutting tool insert of a carbide alloy, it comprises polygon or circular main body substantially, this main body has at least one rake face and at least one clearance plane, it is characterized in that: the composition of described blade is as follows, the Co of 4.4-6.6wt-%, the cubic carbide of 4-8.5wt-%, the WC of surplus, CW is than in the 0.78-0.92 scope, and the thickness of surf zone is 10-40 μ m, and form by cubic carbide TiC, TaC and/or NbC, described blade to small part is coated with the thick coating of 10-25 μ m, and this coating comprises at least one TiC _xN _yLayer, x 〉=0 wherein, y 〉=0 and x+y=1, and α-Al ₂O ₃Layer, this α-Al ₂O ₃Layer be a skin, its at least on rake face,

And,

On described at least one rake face,

-TiC _xN _yThe layer thickness from 3 μ m to 15 μ m, and tensile stress level be 50-500MPa and

-α-Al ₂O ₃The thickness of layer is from 3 μ m, and to 12 μ m, it is an outermost layer, and XRD diffracted intensity ratio I (012)/I (024) 〉=1.3, and has average Ra value MRa＜0.12 μ m at least on the smear metal contact zone of rake face, and on described at least one clearance plane,

-TiC _xN _yThe layer tensile stress in the scope of 500-700Mpa, and

-α-Al ₂O ₃XRD diffracted intensity ratio I (the 012)/I (024)＜1.5 of layer,

Perhaps,

On described at least one rake face and described at least one clearance plane,

-TiC _xN _yThe layer thickness from 3 μ m to 15 μ m, and tensile stress level be 50-500MPa and

-α-Al ₂O ₃The thickness of layer is from 3 μ m to 12 μ m, XRD diffracted intensity ratio I (012)/I (024) 〉=1.3, and it is the outermost layer on the rake face, and on the smear metal contact zone of rake face, has average Ra value MRa＜0.12 μ m at least, and on described clearance plane, outermost layer is made up of the heat-resisting enamelled coating or the colored PVD layer of colour.

2. coated cutting tool as claimed in claim 1 is characterized in that: at described TiC _xN _yLayer and described Al ₂O ₃Has the TiC that thickness is 0.2-2 μ m between the layer _xN _yO _zBinder course, x 〉=0, z＞0, and y 〉=0.

3. as each the described coated cutting tool in the above-mentioned claim, it is characterized in that: described α-Al ₂O ₃Layer has along the texture of 012 direction texture coefficient T C (012)＞1.3.

4. coated cutting tool as claimed in claim 1 is characterized in that: described α-Al ₂O ₃Layer has along the texture of 012 direction texture coefficient T C (012)＞1.5.

5. coated cutting tool as claimed in claim 1 is characterized in that: described α-Al ₂O ₃Layer has along the texture of 110 directions texture coefficient T C (110)＞1.5.

6. coated cutting tool as claimed in claim 1, it is characterized in that: described coating comprises the extra play between blade substrate and above-mentioned layer, this extra play is made up of one or more metal nitride and/or carbide and/or the oxide that is selected from the following metal: Ti, Nb, Hf, V, Ta, Mo, Zr, Cr, W and Al, total coating layer thickness of described extra play＜5 μ m.

7. coated cutting tool as claimed in claim 1 is characterized in that: the thickness of the described surf zone of being made up of cubic carbide is from 15 μ m to 35 μ m.

8. coated cutting tool as claimed in claim 1 is characterized in that: the thickness of the described surf zone of being made up of cubic carbide is from 10 μ m to 25 μ m.

9. coated cutting tool as claimed in claim 1 is characterized in that: the composition of described blade is as follows, the Co of 4.4-6.0wt-%, the cubic carbide of 4-8.5wt-%, the WC of surplus.

10. coated cutting tool as claimed in claim 1 is characterized in that: the composition of described blade is as follows, the Co of 5.0-5.8wt-%, the cubic carbide of 4-8.5wt-%, the WC of surplus.

11. coated cutting tool as claimed in claim 1 is characterized in that: described at least one TiC _xN _yThe thickness of layer is from 4 μ m to 13 μ m, and described α-Al ₂O ₃The thickness of layer is from 3.5 μ m to 11 μ m.

12. coated cutting tool as claimed in claim 1 is characterized in that: described at least one TiC _xN _yThe tensile stress level of layer is 50-450MPa.

13. coated cutting tool as claimed in claim 1 is characterized in that: on described at least one rake face, described α-Al ₂O ₃XRD diffracted intensity ratio I (the 012)/I (024) 〉=1.5 of layer.

14. coated cutting tool as claimed in claim 1 is characterized in that: described α-Al ₂O ₃Layer has average Ra value MRa≤0.10 μ m at least on the smear metal contact zone of rake face.

15. coated cutting tool as claimed in claim 1 is characterized in that: described α-Al of XRD diffracted intensity ratio I (012)/I (024)＜1.5 ₂O ₃Layer is coated with 0.1-2 μ m thick TiN, TiC _xN _y, ZrC _xN _yOr the TiC layer, thereby on clearance plane, provide different colors for blade.