DE102012022466A1 - Coated cutting insert for removing material i.e. chip formation, from workpiece, has multilayer coating scheme including aluminum oxide layer and outer layer exhibiting blasted stress condition - Google Patents

Abstract

The insert (10) has a multilayer coating scheme including an aluminum oxide layer and an outer layer made of zirconium carbon nitride or hafnium carbon nitride, where the outer layer is placed on the aluminum oxide layer. The outer layer exhibits a blasted stress condition ranging 700 megapascal to -4.0 gigapascal or -2.0 gigapascal and -4.0 gigapascal. The multilayer coating scheme comprises innermost titanium nitride and a titanium carbo-nitride layer on a titanium nitride layer, where the aluminum oxide layer is arranged on the titanium carbo-nitride layer. An independent claim is also included for a method for manufacturing a coated cutting insert.

Description

RELATED APPLICATION DATA

According to 35 U.S.C. § 120, the present application is a continuation-in-part of US Patent Application No. 12 / 615,530, filed on Nov. 10, 2008, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a coated cutting insert suitable for removing material from a workpiece, e.g. B. in the chip-forming machining of a workpiece. In particular, the present invention relates to a cutting insert suitable for removing material from a workpiece, the coated cutting insert comprising a substrate coated with a multi-layer coating of a carbonitride of Zr or Hf and Al ₂ O ₃ . The coating scheme includes an exposed Zr or Hf coating layer having a compressive stress.

The U.S. Patent No. 6,224,968 for van den Berg et al. (Assigned to Kennametal Inc.) discloses the use of a coating comprising a first TiN layer, a second carbonitride layer, a third Al ₂ O ₃ layer and an outer Zr, Hf, V, Nb, Ta or Cr Carbonitride layer on a cemented carbide, steel, cermet or ceramic substrate.

The U.S. Patent No. 6,884,496 for Westphal et al. (Assigned to Kennametal Inc.) discloses a method of increasing the compressive residual stress or reducing the tensile residual stress of a Zr or Hf carbonitride coating layer by dry blasting the material with a spray-compacted hard material metal granules.

The U.S. Patent No. 6,350,510 for Konig et al. (Assigned to Kennametal Inc.) discloses a multiphase layer of Zr or Hf carbonitride with internal compressive stresses. The compressive stress of the Zr or Hf layer is the result of an uninterrupted CVD coating process between 900 ° C and 1100 ° C, followed by a heat treatment.

The US Pat. No. 2009/0004449 and 2009/0004440 for Ban et al. (Assigned to Kennametal Inc.) discloses a wet pressure blast method for a cutting insert having an outer wear resistant coating comprising M (O _x C _y N _z ) wherein M is selected from the group comprising one or more of the following: titanium, hafnium, zirconium, chromium , Titanium-aluminum alloy, hafnium-aluminum alloy, zirconium-aluminum alloy, chromium-aluminum alloy and their alloys, wherein x> 0, y≥0, z≥0 and y + z> 0.

BRIEF SUMMARY OF THE INVENTION

A coated cutting insert is provided for removing material from a workpiece with a substrate. A wear resistant coating on the substrate comprising an aluminum oxide (Al ₂ O ₃ ) layer and a Zr or Hf carbonitride outer layer deposited on the aluminum oxide layer. In some embodiments, the alumina layer is an alpha alumina layer. The alumina layer is a κ-alumina layer in some embodiments. In some embodiments, the alumina layer comprises a mixture of α-alumina and κ-alumina. Further, the Zr or Hf carbonitride outer layer is subjected to wet pressure jet treatment after coating. The wet pressure blasting method changes the stress state of the Zr or Hf carbonitride outer layer from an initial tensile or light compressive stress state to a more pressure stress state.

One aspect of the invention is to provide a coated cutting insert comprising a substrate and a multilayer coating scheme comprising an Al ₂ O ₃ layer and an outer layer of ZrCN or HfCN on the Al ₂ O ₃ layer, the outer layer being blasted Stress state in the range between -700 MPa and about -4.0 GPa as measured by X-ray diffraction using the psi tilt method and the (220) reflection of ZrCN. As described herein, the Al ₂ O ₃ layer may be an α-Al ₂ O ₃ layer, a κ-Al ₂ O ₃ layer or a layer comprising a mixture of α-Al ₂ O ₃ and κ-Al ₂ O Be ₃ .

In some embodiments, a coated cutting insert as described herein comprises a substrate and a multilayer coating scheme comprising an α-Al ₂ O ₃ layer and an outer layer of ZrCN or HfCN on the α-Al ₂ O ₃ layer, wherein the α- Al ₂ O ₃ layer has a blasted stress state in the range between 300 MPa and about -1.0 GPa as measured by X-ray diffraction using the psi tilt method and the (024) reflection of α-Al ₂ O ₃ . In some embodiments, a coating cutting insert as described herein comprises a substrate and a multilayer coating scheme comprising a κ-Al ₂ O ₃ layer and an outer layer of ZrCN or HfCN on the κ-Al ₂ O ₃ layer, wherein the κ-Al ₂ O ₃ layer has a blasted stress state in the range between 200 MPa and about -1.3 GPa as measured by X-ray diffraction using the psi tilt method and the (122) reflection of κ-Al ₂ O ₃ .

A method of making a coated cutting insert, in some embodiments, comprises the steps of providing a substrate, coating the substrate with a multi-layer wear resistant coating having an Al ₂ O ₃ layer and an outer Zr or Hf carbonitride outer layer on the Al ₂ O ₃ layer and subjecting the outer layer of a wet pressure jet treatment. In some embodiments of the methods described herein, the Al ₂ O ₃ layer may be an α-Al ₂ O ₃ layer, a κ-Al ₂ O ₃ layer, or a layer comprising a mixture of α-Al ₂ O ₃ and κ -Al ₂ O ₃ , be.

BRIEF DESCRIPTION OF THE DRAWINGS

The following is a brief description of the drawings which form part of this patent application. Show it:

1 an isometric view of a specific embodiment of a coated cutting insert of the present invention, wherein the coated cutting insert is in a re-radiated state;

2 a partial cross-sectional view of the coated cutting insert 1 , The cut represents a portion of the coated cutting insert along the cutting line AB and near the surface of the insert.

3 a micrograph of a portion of a coated cutting insert according to an embodiment of the present invention. The section shows a dome seam showing the substrate and the coating layers on the rake surface of the insert.

DETAILED DESCRIPTION

Referring to the drawings shows 1 a coated cutting insert 10 according to an embodiment of the present invention. The cutting insert 10 is suitable for removing material from a workpiece, e.g. B. in the chip-forming machining of a workpiece. The coated cutting insert 10 can be a cutting corner 11 exhibit. 2 shows a cross-sectional view of the section of 1 along the cutting line AB and at the cutting corner 11 ,

In relation to 2 points the cutting insert 10 a substrate 12 with a multi-layer coating on top. The substrate comprises a WC cemented carbide, cermet, ceramic or steel. According to one embodiment of the present invention and progressively outwardly starting from the innermost coating adjacent to the substrate, the layers of the multilayer coating close a TiN layer 13 , a TiCN layer 14 , an Al ₂ O ₃ layer 15 and an outer coating 16 one. The TiCN layer 14 may be a moderate temperature TiCN coating or a high temperature TiCN coating. In a particular embodiment, the Al ₂ O ₃ layer is 15 a structured α-Al ₂ O ₃ with a predominant (104) growth structure. In another embodiment, the Al ₂ O ₃ layer 15 a κ-Al ₂ O ₃ layer. Furthermore, in some embodiments, the Al ₂ O ₃ layer is 15 a mixture of α-Al ₂ O ₃ and κ-Al ₂ O ₃ . In some embodiments, where the Al ₂ O ₃ layer 15 is a mixture of α-Al ₂ O ₃ and κ-Al ₂ O ₃ , the κ / α ratio is greater than 1. In some embodiments, the κ / α ratio is greater than 10 or greater than 100. The outer coating 16 comprises a Zr-based or Hf-based carbonitride, preferably ZrCN.

In a particular embodiment of the present invention, a tie layer 18 between the Al ₂ O ₃ layer 15 and an outer coating 16 be arranged. The binding layer 18 may include M (O _x C _y N _z ) wherein M is selected from the group comprising one or more of the following: titanium, hafnium, zirconium, chromium, titanium-aluminum alloy, hafnium-aluminum alloy, zirconium-aluminum alloy, chromium-aluminum alloy and their alloys; where x ≥ 0, y ≥ 0, z ≥ 0 and y + z> 0. If Aluminum is contained in the "M" component of the wear indicating layer, it is in combination with one or more other of the other elements (ie, titanium, hafnium, zirconium, chromium). Another embodiment of the present invention provides a (Ti _1-b Al _b ) (O _x C _y N _z ) layer 17 where 0≤b <1, x≥0, y≥0, z≥0 and x + y + z> 0. The (Ti _1-b Al _b ) (O _x C _y N _z ) layer 17 is in some embodiments between the TiCN layer 14 and the Al ₂ O ₃ layer 15 arranged.

3 Figure 11 is a micrograph of a portion of a coated cutting insert according to one embodiment of the present invention. The section shows a dome seam showing the substrate and the coating layers on the rake surface of the insert. The micrograph shows a WC co-substrate 20 with a multi-layer coating on top. Starting with the coating layer adjacent to the substrate and progressing outwardly, the following layers are a TiN layer 22 , an MT-TiCN layer 24 , a TiOCN layer 26 , an α-Al ₂ O ₃ layer 28 and a ZrCN layer 30 ,

The Zr or Hf carbonitride outer layer coating can be applied by CVD, wherein the gas phase at a reaction temperature between 700 ° C and 1100 ° C and preferably at pressures between 5 kPa and 100 kPa in addition to H ₂ and / or Ar and chlorides of above metals also contains carbon donors and nitrogen donors having a C - N molecular group. This is preferably a cyanide group having a triple bond between the carbon and nitrogen whose spacing at room temperature is between 0.114 and 0.118 nm. Such compounds are hydrogen cyanide, cyanamide, cyanogen, cyanoacetylene or acetonitrile. Alternatively or in part, it is also possible to use those gaseous compounds which have CN molecule groups with a single bond between the carbon and the nitrogen. Molecules with single CN bonds include methylamine and ethylenediamine. The present invention includes, within this scope, appropriate substances containing the cyanide group; Compounds of this type are known in principle from the prior art. Other gaseous media which can form cyano groups at the reaction temperature may be introduced into the reaction vessel.

The thickness of the TiN layer 13 may be 0 to 2.0 microns, z. B. 0.1 to 0.5 microns. The thickness of the TiCN layer 14 may be 1.0 to 20.0 microns, z. B. 2.0 to 10 microns. The thickness of the Al ₂ O ₃ layer 15 may be 1.0 to 15.0 μm, e.g. B. 2.0 to 8.0 microns. In some embodiments, where the Al ₂ O ₃ layer is κ-Al ₂ O ₃ , the Al ₂ O ₃ layer comprises a single κ-Al ₂ O ₃ layer or multiple κ-Al ₂ O ₃ layers. For example, in some embodiments, an Al ₂ O ₃ layer of a coating as described herein comprises 2 to 30 κ-Al ₂ O ₃ layers. Furthermore, in some embodiments, an Al ₂ O ₃ layer comprises alternating layers of κ-Al ₂ O ₃ and α-Al ₂ O ₃ . In some embodiments, the (T _{1 -b} Al _b ) (O _x C _y N _z ) layers are between multiple κ-Al ₂ O ₃ layers or alternating layers of κ-Al ₂ O ₃ and α-Al ₂ O ₃ arranged. The thickness of the outer coating 16 may be 0.5 to 5.0 microns, for. B. 1.0 to 3.0 microns. The post-coating wet pressure blasting step removes the outer coating layer 16 to a certain extent. The thickness of the outer coating 16 may be 0.5 to 4.5 microns, z. B. 1.0 to 3.0 microns.

The multilayer coating is subjected to a post-coating wet pressure jet treatment. The post-coat wet pressure jet process step comprises pneumatically exposing the alumina particles to a liquid (eg, water) slurry to impact all surfaces of the pre-blast coating regime. The post-coating wet pressure jet step converts the tensile stress in the outer layer to a compressive stress or increases the compressive stress of the outer layer. The post-coating wet pressure jet step also smoothes the surface of the outer coating layer 16 , It is clear that the wet pressure blasting step changes the state of stress and the surface of the outer coating 16 smoothes. The outer coating 16 (as deposited) is under slight tension or pressure. At a slight draft, the post-coating wet pressure jet step converts the tensile stress of the outer coating 16 to a re-radiated pressure voltage level. In the case of light pressure, the post-coating wet pressure blasting step increases the compressive stress of the outer coating layer 16 further.

The post-coating wet pressure blasting step also smoothes the outer coating 16 , In one alternative, the exposed aluminum oxide coating layer has a surface roughness R _a of between about 0.2 μm and about 0.5 μm using a WYKO measuring technique. In another alternative, the exposed aluminum oxide coating layer exhibits a surface roughness Ra of between about 0.2 μm and about 0.4 μm using a WYKO measuring technique. In yet another alternative, the exposed aluminum oxide coating layer exhibits a surface roughness R _a of between about 0.3 μm and about 0.4 μm using a WYKO measuring technique. In another alternative, the exposed alumina layer has a surface roughness R _a of less than 0.2 μm using the WYKO measurement. With regard to the WYKO technique, a sampling range of 0.3 mm to 0.2 mm was chosen for the WYKO measurement in vertical scanning interferometry mode.

In one alternative of the wear-resistant coating scheme, the outer coating exhibits a pre-blasted (or as deposited) stress state equal to between about 100 MPa tensile stress to about -400 MPa compressive stress. As used herein, stress states of a positive number coating refer to a tensile state and a negative number to a compressive stress state. Upon completion of the wet pressure radiation, the outer coating layer is facing 16 a compressive stress state of between -700 MPa and about -4.0 GPa. In another alternative, the outer coating 16 a stress state of between -2.0 GPa and about -4.0 GPa after completion of the wet-pressure radiation.

In a further alternative of the wear-resistant coating scheme shows the Al ₂ O ₃ layer 15 a pre-blasted (or as deposited) stress state in the range of about 200 MPa tensile stress to about 800 MPa tensile stress. After completion of the wet pressure radiation, the Al ₂ O ₃ layer 15 a tensile / compressive state of between 300 MPa and about -1.0 GPa. In some embodiments, the Al ₂ O ₃ layer has a tensile / compressive stress state in the range of about 200 MPa to about -1.3 GPa upon completion of the wet pressure radiation. The Al ₂ O ₃ layer, in some embodiments, has a compressive stress state in the range of about -200 MPa to about -1.5 GPa upon completion of the wet-pressure radiation. In some embodiments, the Al ₂ O ₃ layer has a compressive stress state in the range of about -500 MPa to about -1.0 GPa upon completion of the wet pressure radiation. As further described herein, the Al ₂ O ₃ layer having a tensile stress state as cited herein may also include an α-Al ₂ O ₃ layer, a κ-Al ₂ O ₃ layer or a layer comprising a mixture of α-Al ₂ O ₃ and κ-Al ₂ O ₃ .

With regard to the measurement technique for the stress of a ZrCN outer coating, the technique is an X-ray diffraction technique. The X-ray diffraction measurement is based on the psi tilt method and the reflection (220) of the ZrCN coating layer was selected for the measurement. Psi slopes of 0 degrees, 28.9 degrees, 43.1 degrees, 56.8 and 75 degrees were selected for the measurement of residual stress levels. Positive and negative psi slopes have been selected to provide the data necessary to determine possible shearing loads. In addition, three Phi rotation angles (0 degrees, 45 degrees and 90 degrees) were selected to provide the data required to determine the biaxial stress status of the material.

worin:

S₁ und ½ S2

für die röntgen-elastischen Konstanten stehen

d_φψ

für die gemessene Scheitelpunkt-d-Beabstandung für die psi-Neigung und Phi-Drehung steht

d₀

für die spannungsfreie Scheitelpunkt-d-Beabstandung der gebeugten Reflexion steht

δ₁ und δ₂

für die primären Spannungen

σ_φ = σ₁cos²φ + σ₂sin²φ stehen.The biaxial stress calculations were performed using the following equation:

wherein:

S ₁ and ½ S2

stand for the X-ray-elastic constants

d _φψ

for the measured vertex d spacing for the psi slope and phi rotation

d ₀

represents the stress-free vertex-d spacing of the diffracted reflection

δ ₁ and δ ₂

for the primary voltages

σ _φ = σ ₁ cos ² φ + σ ₂ sin ² φ stand.

The Young's modulus (E) is given as 434 GPa, the Poisson's number (v) as 0.2 and the X-ray elastic constants (S ₁ and S ₂ ) as -0.46 × 10 ⁶ mm ² / N and 2, respectively. 76 × 10 ⁶ mm ² / N to calculate the stress in the ZrCN coating. Similar measurements can be made for a HfCN coating.

With regard to the measurement technique for the voltage of the Al ₂ O ₃ layer, the technique is substantially the same as that described above, with the following exceptions. In the embodiments in which When the Al ₂ O ₃ layer is an α-Al ₂ O ₃ layer, the reflection (024) of the α-Al ₂ O ₃ layer was selected for the measurement. The Young's modulus (E) is given as 401 GPa, the Poisson's number (ν) as 0.22 and the X-ray elastic constants (S ₁ and S ₂ ) as -0.53 × 10 ⁶ mm ² / N and 2, respectively. 94 × 10 ⁶ mm ² / N for calculating the stress in the α-Al ₂ O ₃ coating. Furthermore, in the embodiments where the Al ₂ O ₃ layer is a κ-Al ₂ O ₃ layer, the reflection (122) of the κ-Al ₂ O ₃ layer was selected for the measurement. The Young's modulus (E) for the κ-Al ₂ O ₃ layer is given as 408 GPa, the Poisson number (ν) as 0.22, and the X-ray elastic constants (S ₁ and S ₂ ) as -0.56 × 10 ⁶ mm ² / N or 3.01 × 10 ⁶ mm ² / N for calculating the stress in the κ-Al ₂ O ₃ coating.

The wet pressure radiation is achieved using a slurry comprising alumina particles and water. The slurry of alumina particles and water is pneumatically projected on the surface to impact the surface of the substrate. The essential parameters of the alumina-water slurry are the concentration by weight (i.e., the alumina particles) in volume percent and the alumina particle size in microns (microns). In one alternative, the slurry comprises between about 5% by volume and about 35% by volume of alumina particles with the conditioned water. In another alternative, the slurry comprises between about 8% by volume and about 25% by volume of alumina particles with the conditioned water. The particle size in one alternative may be an alumina particle size in the size range between about 20 μm and about 100 μm. In another alternative, the alumina particles may be in size in the range between about 35 μm and about 75 μm.

The operating parameters for the wet pressure blasting step are pressure, angle of incidence and duration. In this application, the angle of incidence is about ninety degrees, that is, the particles strike the surface at a 90 degree angle. In one alternative, the pressure varies between about 35 pounds per square inch (psi) and about 55 psi. In another alternative, the pressure varies from about 40 pounds per square inch (psi) to about 50 psi. The duration of the wet-pressure radiation varies with the specific wet-pressure radiation operation, the aim being to achieve optimum stress levels in the outer coating and the Al ₂ O ₃ -layer. Exemplary durations include between about 6 seconds and about 45 seconds. An area of duration is between about 9 seconds and about 30 seconds. Yet another range of duration is between about 12 seconds and about 21 seconds.

With respect to a method of manufacturing a coated cutting insert, the basic steps are the following steps. The first step comprises providing a substrate, wherein the substrate is selected from the group consisting of hard metals, cermets or ceramics.

Secondly, the substrate is coated with a multi-layer, wear-resistant coating having an Al ₂ O ₃ layer and an outer Zr or Hf carbonitride outer layer on the Al ₂ O ₃ layer. As described herein, the Al ₂ O ₃ layer may be an α-Al ₂ O ₃ layer, a κ-Al ₂ O ₃ layer or a layer comprising a mixture of α-Al ₂ O ₃ and κ-Al ₂ O Be ₃ . Third, the coating is subjected to a wet pressure jet treatment.

Specific examples of the inventive coated cutting insert and comparative tests thereof are listed below. In a comparative test, the tool life in minutes of an inventive coated cutting insert versus tool life in minutes was measured by two prior art cutting inserts.

Table 1 shows the basic process parameters used to deposit the alumina-containing base coat region and the zirconium-containing outer coat region for the specific examples, both for the prior art cutting inserts and for the inventive ceramic cutting insert. In this regard, the method of the parameters in Table 1 represents the steps used to apply a coating scheme to the surface of the cemented carbide substrate. Table 1 - Process parameters for the invented coating process materials Temperature (° C) Pressure (mbar) Total time (minutes) used gases TiN 905 160 60 H _2, N _2, TiCl4, HCl TiCN 880 70-90 240 TiCl ₄ , H ₂ , N ₂ , (Ti _1-b Al _b ) (O _x C _y N _z ) 1000 75-500 70 H ₂ , N ₂ , CH ₄ , TiCl ₄ , CO, AlCl ₃ α-Al ₂ O ₃ 1000 75 300 H ₂ , A ₁ Cl ₃ , CO ₂ , HCl, H ₂ S ZrCN 960-1000 80 240 ZrCl ₃ , H ₂ , CH ₃ CN, Ar

The above steps follow each other, beginning with the TiN step via the ZrCN application step.

With respect to the above steps in Table 1, control of Al ₂ O ₃ to ensure α-phase results is important in some embodiments for the integrity of the outer coating. The poor adhesion between ZrCN and other alumina phases can lead to exfoliation of the outer layer during wet pressure radiation or cutting of the metal. Nevertheless, the coated cutting inserts of the present invention having a κ-Al ₂ O ₃ layer can exhibit adhesion between ZrCN and κ-Al ₂ O ₃ suitable for wet-pressure radiation and / or for metal cutting applications, thereby providing an alternative to the α- Al ₂ O ₃ embodiments is offered. Therefore, with respect to the above steps in Table I, the deposition of Al ₂ O _{3 is} controlled in some embodiments to ensure the κ phase results.

In a first example, the prior art cutting inserts used for the comparative test included a coating scheme similar to that of the present invention, except that the prior art inserts employ a TiCN / TiN outer coating layer , The cutting inserts of the present invention of this first example indicated the coating structure in Table I using an α-Al ₂ O ₃ layer together with the ZrCN outer layer. Both the prior art coated cutting inserts and the inventive coated ceramic cutting insert were cutting inserts of the prior art ANSI standards CNMA432 , Table 2. Post-coating jet parameters parameter description Composition alumina particle water slurry In the range of 5 to 35% by volume Size of the alumina particles In the range of 20 μm-100 μm Pressure during the impact process In the range of 35 to 55 psi Duration of impact In the range of 6 to 45 seconds

For the comparison test for tool life measurement, the parameters were as follows: Workpiece material: 80-55-06 ductile iron; Speed equal to 656 surface feet per minute (sfm) (200 surface meters per minute); a foot rate equal to 0.004 inches (0.1 millimeter) per revolution (ipr); a cut depth (doc) equal to 0.08 inches (2.03 millimeters); a guide angle equal to -5 degrees with coolant. The failure criteria were: UNF equal to 0.012 inches (0.3 millimeters) maximum; Nose wear (NW) equal to 0.012 inches (0.3 millimeters); Depth of cut indentation (DOCN) equal to 0.012 inches (0.3 millimeters); CR equals 0.004 inches (0.1 millimeter); and TW equal to 0.012 inches (0.3 millimeters).

In the comparative test, samples, ie, three each of the prior art coated cutting inserts and three inventive coated cutting inserts, were run through. The results of the comparative test are shown in Table 3 below. Table 3. Tool life results from the comparison test Tool life (in minutes) / failure mode State of the art - 1A 10.3 / NW Prior art - 2A 9.6 / NW Prior Art - 3A 7.3 / NW Invention - 1 14.0 / NW Invention - 2 9.9 / NW Invention - 3 11.9 / NW

These cut test results show an improvement of approximately 30% of the life (tool life) of the inventive cutting inserts in terms of wear resistance as compared to the wear resistance of the prior art cutting inserts.

A second comparative trade mark score was also performed. A wet-turn cycle was used with the following parameters: Workpiece materials: 316 Ti stainless steel; Speed equal to 656 surface feet per minute (sfm) (200 surface meters per minute); a foot rate equal to 0.01 inches (0.25 millimeters) per revolution and a cutting depth equal to 0.08 inches (2 millimeters); a lead angle equal to -5 degrees. The prior art is a commercial carbide cutting tool coated with kappa Al ₂ O ₃ having a ZrCN topcoat treated with dry radiation. The cutting insert of the present invention in this example indicated the coating architecture of Table I. Both the prior art coated cutting inserts and the inventive coated cutting insert exhibit the nature of the art ANSI standards CNMG432RP on. Table 4 below presents the results of a comparison of tool life determined by the depth of cut score for the prior art coated cutting inserts and the inventive coated cutting insert. The failure criterion is: depth of cut indentation (DOCN) equal to 0.012 inches (0.3 millimeters). Table 4 Comparison of cutting inserts of the prior art and inventive cutting inserts Tool life according to DOCN (in minutes) Use of the prior art 10.7 Inventive use 12.7

The inventive cutting inserts showed a 20% improvement in the depth of notch resistance in the machining of 316 Ti stainless steel.

The patents and other documents cited herein are hereby incorporated by reference in their entirety. Other embodiments of the invention will be apparent to one of ordinary skill in the art having regard to the specification or practice of the invention disclosed herein. The specification and examples are merely illustrative and are not intended to limit the scope of the invention in any way. The following claims set forth the true scope and spirit of the invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 6224968 [0003]
• US 6884496 [0004]
• US 6350510 [0005]
• US 2009/0004449 [0006]
• US 2009/0004440 [0006]

Cited non-patent literature

• ANSI standards CNMA432 [0037]
• ANSI standards CNMG432RP [0041]

Claims (27)

A coated cutting insert comprising: a substrate; and a multilayer coating scheme comprising: a κ-Al ₂ O ₃ layer; and an outer layer of ZrCN or HfCN on the κ-Al ₂ O ₃ layer, the outer layer having a blasted stress state in the range between about -700 MPa and about -4.0 GPa, as determined by X-ray diffraction using the psi Tilting process and the (220) reflection of ZrCN or HfCN, and a bonding layer between the κ-Al ₂ O ₃ layer and the outer layer, wherein the bonding layer comprises M (O _x C _y N _z ), wherein M is selected is from the group comprising one or more of the following: titanium, hafnium, zirconium, chromium, titanium-aluminum alloy, hafnium-aluminum alloy, zirconium-aluminum alloy, chromium-aluminum alloy and their alloys, and x ≥ 0, y ≥ 0, z ≥ 0 and y + z> 0, and wherein when M is aluminum, at least one of titanium, hafnium, zirconium or chromium is also present. The coated cutting insert of claim 1, wherein the blasted stress state is in the range between about -2.0 GPa and about -4.0 GPa. The coated cutting insert of claim 1 or 2, wherein the multilayer coating scheme further comprises an innermost TiN layer and a TiCN layer on the TiN layer, wherein the κ-Al ₂ O ₃ layer is disposed on the TiCN layer. A coated cutting insert according to any one of claims 1 to 3, wherein the κ-Al ₂ O ₃ layer has a blasted stress state ranging from 200 MPa to -1.3 GPa as determined by X-ray diffraction using the psi tilt method and of the (122) reflection of κ-Al ₂ O ₃ . The coated cutting insert of claim 1, wherein the κ-Al ₂ O ₃ layer further comprises a mixture with α-Al ₂ O ₃ . The coated cutting insert of claim 1, wherein the κ-Al ₂ O ₃ layer has a blasted stress state that is in the range of -200 MPa to -1.5 GPa as determined by X-ray diffraction using the psi tilt method and (122 ) Reflection of κ-Al ₂ O ₃ . The coated cutting insert of claim 3, further comprising a (Ti _1-b Al _b ) (O _x C _y N _z ) layer between the TiCN layer and the κ-Al ₂ O ₃ layer, where 0 ≤ b <1, x ≥ 0, y ≥ 0, z ≥ 0 and x + y + z> 0. The coated cutting insert of claim 1, wherein the substrate comprises a cemented carbide, a cermet or a ceramic. The coated cutting insert of claim 1, wherein the outer layer has a thickness of 0.5 μm to 4.5 μm, and the κ-Al ₂ O ₃ layer has a thickness of 1.0 μm to 15.0 μm. The coated cutting insert according to claim 9, wherein the κ-Al ₂ O ₃ layer a plurality of κ-Al ₂ O ₃ layers. The coated cutting insert of claim 9, wherein the κ-Al ₂ O ₃ layer further comprises alternating layers of κ-Al ₂ O ₃ and α-Al ₂ O ₃ . A coated cutting insert comprising: a substrate; and a multilayer coating scheme comprising: a κ-Al ₂ O ₃ layer; and an outer layer of ZrCN or HfCN on the κ-Al ₂ O ₃ layer, wherein the κ-Al ₂ O ₃ layer has a blasted stress state in the range between about 200 MPa and about -1.3 GPa, as by means X-ray diffraction was measured using the psi tilt method and the (122) reflection of κ-Al ₂ O ₃ . The coated cutting insert of claim 12, wherein the multilayer coating scheme further comprises an innermost TiN layer and a TiCN layer on the TiN layer, wherein the κ-Al ₂ O ₃ layer is disposed on the TiCN layer. The coated cutting insert of claim 12, further comprising a bonding layer between the κ-Al ₂ O ₃ layer and an outer layer, wherein the bonding layer comprises M (O _x C _y N _z ) wherein M is selected from the group comprising one or more more of the following: titanium, hafnium, zirconium, chromium, titanium-aluminum alloy, hafnium-aluminum alloy, zirconium-aluminum alloy, chromium-aluminum alloy and their alloys, and x≥0, y≥0, z≥0 and y + z> 0 , and wherein when M is aluminum, at least one of titanium, hafnium, zirconium or chromium is also present. The coated cutting insert of claim 14, further comprising a (Ti _{1 -b} Al _b ) (O _x C _y N _z ) layer between the TiCN layer and the κ-Al ₂ O ₃ layer, where 0 ≤ b <1, x ≥ 0, y ≥ 0, z ≥ 0 and x + y + z> 0. The coated cutting insert of claim 12, wherein the substrate comprises a cemented carbide, a cermet or a ceramic. The coated cutting insert according to claim 12, wherein the κ-Al ₂ O ₃ layer a plurality of κ-Al ₂ O ₃ layers. The coated cutting insert of claim 12, wherein the κ-Al ₂ O ₃ layer further comprises alternating layers of κ-Al ₂ O ₃ and α-Al ₂ O ₃ . The coated cutting insert of claim 12, wherein the outer layer has a thickness of 0.5 μm to 4.5 μm, and the κ-Al ₂ O ₃ layer has a thickness of 1.0 μm to 15.0 μm. The coated cutting insert of claim 12, wherein the κ-Al ₂ O ₃ layer has a blasted stress state in the range between about -200 MPa and about -1.5 GPa. A method of making a coated cutting insert comprising the steps of: providing a substrate; Coating the substrate with a multi-layer, wear-resistant coating having a κ-Al ₂ O ₃ layer and an outer Zr or Hf carbonitride outer layer on the κ-Al ₂ O ₃ layer; and subjecting the outer layer to a wet pressure jet treatment, wherein the κ-Al ₂ O ₃ layer has a blasted stress state in the range between about 200 MPa to about -1.3 GPa as determined by X-ray diffraction using the PSI tilt method and (122 ) Reflection of κ-Al ₂ O ₃ . A method of making a coated cutting insert according to claim 21, wherein the wet pressure jet treatment uses a slurry comprising alumina particles and water, the alumina comprising from 5% to 35% by volume of the slurry. The method of producing a coated cutting insert according to claim 21, wherein the alumina particles are 20 μm to 100 μm in size. A method of making a coated cutting insert according to claim 21 wherein the slurry is blasted at a pressure of 35 psi to 55 psi and the wet pressure blast process is continued for six seconds to forty five seconds. The method of claim 21, wherein the κ-Al ₂ O ₃ layer further comprises a mixture of α-Al ₂ O ₃ . The coated cutting insert of claim 1, wherein the outer layer of ZrCN or HfCN has a compressive stress state as deposited. The coated cutting insert of claim 12, wherein the outer layer of ZrCN or HfCN has a compressive stress state as deposited.

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