JP2009056537A - Surface-coated cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool the hard coating layer of which achieves excellent chipping resistance and wear resistance in high-speed intermittent cutting work. <P>SOLUTION: In the surface-coated cutting tool on which at least (Ti, Cr)CN layer is formed by deposition for the hard coating layer, at least one layer is composed of (a) (Ti, Cr) CN layer, in which, on an inclination angle frequency distribution graph for normal lines of ä111} faces, the highest peak exists in an inclination angle section in a range of 0-10 deg., and the total of the frequencies occupies a ratio of 45% or more of all the frequencies. At least further one layer is composed of (b) (Ti, Cr)CN layer, in which, on an inclination angle frequency distribution graph for normal lines for ä112} faces, the highest peak exits in an inclination angle section in a range of 0-10 deg., and the total of the frequencies occupies a ratio of 45% or more of all the frequencies. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention exhibits excellent chipping resistance and wear resistance with a high hard coating layer in high-speed intermittent cutting of steel or cast iron that is accompanied by large heat generation and has a large impact and mechanical load on the cutting edge. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool).

On the surface of a substrate composed of tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet (hereinafter collectively referred to as a tool substrate),
(A) All formed by chemical vapor deposition, comprising one or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, and having a total average layer thickness of 0.1 to 15 μm When the Ti compound layer has a total average layer thickness of 2.5 to 15 μm and is represented by a composition formula: (Ti _1−α Cr _α ) CN, the atomic ratio is α: 0.005 to 0.00. A lower layer composed of a carbonitride layer of Ti and Cr satisfying 05,
(B) an upper layer comprising an α-type Al ₂ O ₃ layer formed by chemical vapor deposition and having an average layer thickness of 1 to 15 μm;
In a coated tool provided with the hard coating layer comprised by the above (a) and (b),
The Ti and Cr carbonitride layers of the Ti compound layer of (a) above are individually divided into crystal grains having a cubic crystal lattice existing within the measurement range of the surface polished surface using a field emission scanning electron microscope. Irradiate with an electron beam to measure the tilt angle formed by the normal of the {112} plane that is the crystal plane of the crystal grain with respect to the normal of the surface polished surface. In the inclination angle number distribution graph obtained by dividing the measured inclination angle within the range of 45 degrees for each pitch of 0.25 degree and totaling the frequencies existing in each division, it is within the range of 0 to 10 degrees. An inclination angle distribution graph in which the highest peak exists in the inclination angle section and the sum of the frequencies existing in the range of 0 to 10 degrees occupies 45% or more of the entire frequency in the inclination angle distribution graph is shown. Ti and Cr carbonitride (hereinafter, conventional (Ti, C ) Shown in the CN) layer,
It is known that it exhibits excellent chipping resistance in high-speed heavy cutting.

The conventional (Ti, Cr) CN is
Reaction gas composition (volume%): TiCl ₄ : 2 to 10%, CrCl ₃ : 0.01 to 0.5%, CH ₃ CN: 0.5 to 3%, N ₂ : 30 to 45%, Ar: remaining ,
Reaction atmosphere temperature: 900-1020 ° C.
Reaction atmosphere pressure: 6-20 kPa,
It is known that it is formed by chemical vapor deposition under the following conditions.
JP 2006-334710 A

In recent years, the performance of cutting devices has been remarkably improved. On the other hand, there are strong demands for labor saving and energy saving in cutting, and further cost reduction. In the above conventional coated tool, the conventional (Ti, Cr) CN is used as a lower layer. Al ₂ O ₃ layer is provided as the upper layer, and the conventional (Ti, Cr) CN layer as the lower layer has a predetermined high temperature strength, and the upper layer Al ₂ O ₃ layer is excellent in high temperature hardness. Therefore, there is no problem when it is used for continuous cutting and interrupted cutting under normal conditions such as steel and cast iron. When used in high-speed intermittent cutting of steel and cast iron that are subject to mechanical and mechanical loads, the high-temperature strength of the conventional (Ti, Cr) CN layer provided as the lower layer cannot be said to be sufficient. Satisfying mechanical shock The present situation is that it is difficult to respond, chipping is likely to occur due to mechanical impact force during cutting, and the service life is reached in a relatively short time.

In view of the above, the inventors of the present invention have proposed a conventional (Ti, Cr) CN layer among Ti compound layers in order to improve the chipping resistance and wear resistance of the hard coating layer of the coated tool. As a result of research on the following, the following knowledge was obtained.
(A) In the hard coating layer of the conventional coated tool, the conventional (Ti, Cr) CN layer of the Ti compound layer constituting the lower layer is, for example, as described above, for example, with a normal chemical vapor deposition apparatus.
Reaction gas composition (volume%): TiCl ₄ : 2 to 10%, CrCl ₃ : 0.01 to 0.5%, CH ₃ CN: 0.5 to 3%, N ₂ : 30 to 45%, Ar: remaining ,
Reaction atmosphere temperature: 900-1020 ° C.
Reaction atmosphere pressure: 6-20 kPa,
By chemical vapor deposition under the conditions of
When expressed by the composition formula: (Ti _1-Y Cr _Y ) CN, a (Ti, Cr) CN layer satisfying Y: 0.005 to 0.05 in atomic ratio can be formed. (Ti, Cr) CN layer (conventional (Ti, Cr) CN layer) is a NaCl-type face-centered cubic in which constituent atoms composed of Ti, Cr, carbon (C), and nitrogen (N) are present at lattice points. It has a crystal structure and has excellent high-temperature strength.

(B) Then, the conventional (Ti, Cr) CN layer of (a) is subjected to surface polishing using a field emission scanning electron microscope, as schematically shown in FIGS. 1 (a) and 1 (b). A method of the {112} plane which is the crystal plane of the crystal grain with respect to the normal line of the surface-polished surface by irradiating an electron beam to each crystal grain having a cubic crystal lattice existing within the measurement range of the plane Measure the tilt angle formed by the line, and divide the measured tilt angles within the range of 0 to 45 degrees out of the measured tilt angles by pitch of 0.25 degrees, and count the frequencies existing in each section In the inclination angle distribution graph, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees, and the total of the frequencies existing within the range of 0 to 10 degrees is the inclination angle number distribution graph. Inclination angle frequency distribution graph that accounts for more than 45% of the total frequency at It.

(C) When forming the conventional TiCN layer, the Cr content ratio in the layer is 0.005 to 0.05 in terms of the atomic ratio to the total amount with Ti as described above, whereby the above 0 to 10 degrees. Therefore, the total of the frequencies existing in the range of 45% occupies a ratio of 45% or more of the entire frequencies in the inclination angle frequency distribution graph. Therefore, the Cr content ratio in the conventional (Ti, Cr) CN layer is Even if it deviates from the above range to the lower side or deviates from the higher side, the total frequency within the range of 0 to 10 degrees becomes less than 45%. In this case, the high temperature strength is improved. What you can't do.

(D) Moreover, in a normal vapor deposition apparatus,
Reaction gas composition (volume%): TiCl ₄ : 1 to 5%, CrCl ₃ : 0.7 to 2.5%, CH ₃ CN: 3 to 6%, N ₂ : 20 to 40%, HCl: 0.5 ~2%, H _2: remainder,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 5 to 20 kPa,
When chemical vapor deposition is performed under the conditions, Ti and Cr carbonitride layers are formed by vapor deposition.
Compositional formula: (Ti _1-X Cr _X ) CN, when expressed in terms of atomic ratio, Ti: Cr carbonitride satisfying X: 0.12-0.2 (hereinafter, modified (Ti, Cr)) This modified (Ti, Cr) CN layer has constituent atoms composed of Ti, Cr, carbon (C), and nitrogen (N) at lattice points, respectively. The crystal structure of the NaCl type face centered cubic crystal has the same crystal structure as that of the conventional (Ti, Cr) CN layer, and a higher temperature than the conventional (Ti, Cr) CN layer. Must have strength, high temperature hardness and heat resistance.

(E) About the modified (Ti, Cr) CN layer,
Using a field emission scanning electron microscope, as illustrated in the schematic explanatory diagrams of FIGS. 2A and 2B, the electron beam is individually applied to each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface. Is measured with respect to the normal of the surface polished surface, and the tilt angle formed by the normal of the {111} plane that is the crystal plane of the crystal grain is measured. When the measured inclination angle within the range of 0.25 degrees is divided for every pitch of 0.25 degrees and the inclination angle number distribution graph is formed by counting the frequencies existing in each division, the modification (Ti, Cr 4) As shown in FIG. 4, the CN layer has a sharp maximum peak at a specific position in the tilt angle section. In such a case, the modified (Ti, Cr) CN layer has uniform cooling cracks. Dispersion and thereby modification by increasing the Cr content ( i, Cr) The high temperature strength of the CN layer can be suppressed, and at the same time, excellent high temperature hardness can be maintained. Furthermore, the stability of the grain boundary is increased, and the cracks in the layer generated during the cutting process can be reduced. Propagation is suppressed, and even when a shocking load is intermittently applied to the cutting edge, chipping resistance is greatly improved, and wear resistance is also greatly improved.

(F) As described above, when the modified (Ti, Cr) CN layer is formed, the Cr content in the layer is 0.12 to 0.20 in terms of the ratio (atomic ratio) to the total amount with Ti. By doing so, in the inclination angle number distribution graph of the modified (Ti, Cr) CN layer, the sharpest peak of the {111} plane appears in the range of 0 to 10 degrees of the inclination angle section, and the 0 The frequency ratio existing in the range of -10 degrees shows an inclination angle number distribution graph that occupies a ratio of 45% or more of the entire frequency in the inclination angle number distribution graph. Therefore, the modification (Ti, Even if the Cr content ratio in the Cr) CN layer deviates from the above range to the lower or higher range, the sharp maximum peak in the inclination angle number distribution graph is in the range of 0 to 10 degrees of the inclination angle section. And the above 0 to 10 The frequency ratio existing in the range of less than 45%, in this case, not only can not expect a further heat resistance improvement effect, the decrease in high-temperature strength due to the increase of the Cr content ratio is uniform cooling cracks It cannot be suppressed by dispersion.
That is, the Cr component of the modified (Ti, Cr) CN layer has a desired heat resistance improvement effect at a ratio (atomic ratio) of 0.12 (12 atomic%) or more in the total amount with Ti, When the content ratio exceeds 0.20 (20 atomic%), in high-speed intermittent cutting with high heat generation, the modified (Ti, Cr) CN layer softens rapidly, and it is easy to cause thermoplastic deformation and uneven wear. Therefore, the content ratio needs to be 0.12 to 0.20 in a ratio (atomic ratio) to the total amount with Ti.

(G) Layer structure of hard coating layer The hard coating layer is composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer. It is composed of a compound layer and a (Ti, Cr) CN layer, and at least one of the (Ti, Cr) CN layers is the conventional (Ti, Cr) CN layer, and at least one layer is It must be composed of the modified (Ti, Cr) CN layer.
As described above, the conventional (Ti, Cr) CN layer is excellent in high-temperature strength, but does not have sufficient impact resistance required in high-speed intermittent cutting, but the conventional (Ti, Cr) CN is not provided. By providing a modified (Ti, Cr) CN layer as a constituent layer of the hard coating layer, which has superior high-temperature strength, high-temperature hardness and heat resistance as compared to the layer, and at the same time, excellent impact resistance Since the high-temperature strength of the hard coating layer as a whole can be increased and at the same time the high-temperature hardness can be maintained, the coated tool formed by vapor deposition of the hard coating layer has improved impact resistance during high-speed intermittent cutting, As a result, it exhibits excellent chipping resistance and exhibits excellent wear resistance over a long period of time.
The research results shown in (a) to (g) above were obtained.

This invention was made based on the above research results,
“(1) At least a Ti compound layer, Ti and Cr as a hard coating layer having a total average layer thickness of 4 to 20 μm on the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet In the surface-coated cutting tool formed by vapor deposition of the carbonitride layer of
(A) The Ti compound layer is composed of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer,
(B) At least one of the Ti and Cr carbonitride layers has an average layer thickness of 2 to 15 μm, and
When represented by composition formula: (Ti _1-X Cr _X ) CN, it is a carbonitride layer of Ti and Cr that satisfies X: 0.12-0.2 in atomic ratio,
Further, by using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the normal line of the surface polishing surface is The inclination angle formed by the normal line of the {111} plane, which is the crystal plane of the crystal grain, is measured, and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is set every pitch of 0.25 degrees. In the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak is present in the inclination angle section in the range of 0 to 10 degrees, and within the range of 0 to 10 degrees. Is formed by a carbonitride layer of Ti and Cr showing an inclination angle distribution graph occupying a ratio of 45% or more of the entire frequency in the inclination angle distribution graph,
(C) Further, at least one of the Ti and Cr carbonitride layers has an average layer thickness of 2 to 15 μm, and
When represented by a composition formula: (Ti _1-Y Cr _Y ) CN, it is a carbonitride layer of Ti and Cr satisfying Y: 0.005 to 0.05 in atomic ratio,
Further, by using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the normal line of the surface polishing surface is The inclination angle formed by the normal of the {112} plane, which is the crystal plane of the crystal grain, is measured, and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is set every pitch of 0.25 degrees. In the slope angle distribution graph formed by summing up the frequencies existing in each section, the highest peak exists in the slope angle section in the range of 0 to 10 degrees, and within the range of 0 to 10 degrees. Is formed of Ti and Cr carbonitride layers showing an inclination angle distribution graph that occupies a ratio of 45% or more of the entire frequencies in the inclination angle distribution graph.
A surface-coated cutting tool (coated tool).
(2) The aluminum oxide layer having an average layer thickness of 1 to 15 μm is further formed on the surface of the hard coating layer having a total average layer thickness of 4 to 20 μm by vapor deposition. Surface coated cutting tool (coated tool). "
It has the characteristics.

  Next, the reason why the constituent layers of the hard coating layer of the coated tool of the present invention are numerically limited as described above will be described below.

(A) Ti compound layer The Ti compound layer as a hard coating layer composed of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride oxide layer itself has a predetermined high-temperature strength. In addition to the hard coating layer having high-temperature strength due to the presence thereof, the tool base and the conventional (Ti, Cr) CN layer or the modified (Ti, Cr) CN layer are firmly adhered to each other. Although it has the effect | action which contributes to the adhesive improvement with respect to the tool base | substrate of a hard coating layer, if the total average layer thickness is less than 4 micrometers, the said effect cannot fully be exhibited, On the other hand, the total average layer thickness exceeds 20 micrometers Then, it becomes easy to cause thermoplastic deformation by intermittent cutting, and this causes uneven wear. Therefore, the total average layer thickness of the Ti compound layer was determined to be 4 to 20 μm.

(B) Conventional (Ti, Cr) CN layer As described above, the conventional (Ti, Cr) CN layer has an atomic ratio of the Cr content (Y value) in the layer to the total amount of Ti. By setting 005 to 0.05, in the inclination angle number distribution graph obtained by adding up the inclination angles formed by the normal of the {112} plane, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees. In addition, the total of the frequencies existing in the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire frequencies in the inclination angle frequency distribution graph and has a high temperature strength (Ti, Cr). Although the CN layer can be formed by vapor deposition, if the average layer thickness is less than 2 μm, the desired excellent high-temperature strength improvement effect cannot be exhibited. On the other hand, if the average layer thickness exceeds 15 μm, it causes uneven wear. The thermoplastic deformation that becomes , From becoming so worn accelerates, it determined the average layer thickness and 2 to 15 [mu] m.

(C) Modified (Ti, Cr) CN layer For the modified (Ti, Cr) CN layer of the Ti compound layer, the atomic ratio of the Cr content ratio (X value) in the layer to the total amount of Ti In the inclination angle number distribution graph obtained by adding up the inclination angles formed by the normal lines of the {111} plane by setting to 0.12 to 0.2, the inclination angle section within the range of 0 to 10 degrees is the highest. A modified (Ti, Cr) CN layer is formed in which a peak is present and the total frequency within the range of 0 to 10 degrees occupies 45% or more of the total frequency in the gradient angle distribution graph. And such a modified (Ti, Cr) CN layer has a high temperature of the modified (Ti, Cr) CN layer due to the uniform distribution of cooling cracks, thereby increasing the Cr content. It is possible to suppress a decrease in strength and at the same time excellent In addition, the stability of the grain boundaries is increased, the propagation of cracks in the layer generated during cutting is suppressed, and an intermittent impact load is applied to the cutting edge. In this case, the chipping resistance can be greatly improved and the wear resistance can be improved.
Therefore, even if the content ratio is less than 0.12 or exceeds 0.2, not only the improvement effect of high temperature hardness and heat resistance can be expected, but also the decrease in high temperature strength is suppressed by uniform dispersion of cooling cracks. Therefore, in the intermittent cutting process in which an intermittent and repeated impact load is applied, the wear resistance is inferior due to the occurrence of thermoplastic deformation or uneven wear.
And, as in the case of conventional (Ti, Cr) CN, if the average layer thickness is less than 2 μm, the desired excellent high-temperature strength improvement effect cannot be exhibited, while if the average layer thickness exceeds 15 μm, The average layer thickness was determined to be 2 to 15 μm because thermoplastic deformation that causes uneven wear tends to occur and wear accelerates.

  Regarding C and N, which are constituent components other than Ti and Cr in the conventional (Ti, Cr) CN layer and modified (Ti, Cr) CN layer, the C component improves the hardness of the layer, and The N component has the effect of improving the high-temperature strength, and by coexisting both these components, it becomes a carbonitride layer having high hardness and excellent strength. Therefore, the inclusion of the N component in the layer If the ratio is less than 0.35 (provided that the atomic ratio) is the ratio of the total amount with the C component (= N / (C + N)), the desired strength cannot be ensured. If it exceeds 55, the content ratio of the C component becomes relatively small and the desired high hardness cannot be obtained. Therefore, the C in the conventional (Ti, Cr) CN layer and the modified (Ti, Cr) CN layer Content ratio of N component to total amount with component ( N / (C + N)) is preferably set to 0.35 to 0.55 in atomic ratio.

(D) Layer structure of hard coating layer The hard coating layer is a Ti compound layer comprising at least two of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer. And at least one of the (Ti, Cr) CN layers is the conventional (Ti, Cr) CN layer, and at least one of the modified layers is the modified (Ti, Cr) CN layer. It must be composed of a quality (Ti, Cr) CN layer.
As already described, although the conventional (Ti, Cr) CN layer is excellent in high-temperature strength, it cannot be said to have sufficient impact resistance required in high-speed interrupted cutting, so high-temperature strength, The high temperature strength of the hard coating layer is increased by providing a modified (Ti, Cr) CN layer with excellent impact resistance at the same time as high temperature hardness and heat resistance as a constituent layer of the hard coating layer. At the same time, the high temperature hardness can be maintained, and the Ti compound layer, the modified (Ti, Cr) CN layer, and the conventional (Ti, Cr) CN layer have high adhesion strength to each other, so that they are hard-coated. As a result, the high-temperature strength of the entire layer is further increased, and as a result, the coated tool of the present invention has improved impact resistance during high-speed intermittent cutting of various steels and cast irons, resulting in excellent chipping resistance. With showing So to exert excellent wear resistance for a long time.

Although it is well known that the wear resistance of the coated tool is improved by providing an Al ₂ O ₃ layer as the hard coating layer, in the present invention, Al is further provided on the outermost surface of the hard coating layer. _The wear resistance of the coated tool can be further improved by vapor deposition coating of the ₂ O ₃ layer. At that time, the the Al ₂ O ₃ layer, alpha type the Al ₂ O ₃ layer, but the Al ₂ O ₃ layer of κ type the Al ₂ O ₃ layer such various crystal structures are known, have these crystal structures The remaining Al ₂ O ₃ layer may be coated, and its crystal structure is not particularly limited.
However, when the Al ₂ O ₃ layer is deposited by vapor deposition, if the average layer thickness is less than 1 μm, further improvement in wear resistance of the hard coating layer cannot be expected, while the average layer thickness exceeds 15 μm. If the thickness is too thick, chipping is likely to occur. Therefore, the average layer thickness is preferably 1 to 15 μm.

  In addition, for example, for the purpose of identification before and after the use of the cutting tool, a TiN layer having a golden color tone can be vapor-deposited as the outermost surface layer as necessary. A layer thickness of 0.1 to 1 μm is sufficient.

  The coated tool according to the present invention has a conventional hard coating layer (Ti) even in high-speed intermittent cutting of various steels and cast irons that are accompanied by high heat generation and repeatedly repeatedly subjected to large impact and mechanical loads. , Cr) CN layer has excellent high temperature strength, and at least one layer is composed of a modified (Ti, Cr) CN layer, which further improves high temperature strength and heat resistance. As a result, the hard coating layer exhibits excellent chipping resistance and excellent wear resistance over a long period of time.

  Next, the coated tool of the present invention will be specifically described with reference to examples.

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder and Co powder all having an average particle size of 0.3 to 3 μm as raw material powder These raw material powders are blended in the blending composition shown in Table 1, and then added with wax, ball milled in acetone for 32 hours, dried under reduced pressure, and then pressed into a green compact with a predetermined shape at a pressure of 98 MPa. The green compact was press-molded and vacuum sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour. After sintering, the cutting edge portion had R: 0.07 mm. The tool bases A to F made of a WC-base cemented carbide having a throwaway tip shape specified in ISO · CNMG12041 were manufactured by performing the honing process.

Further, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, blend these raw material powders into the composition shown in Table 2, wet mix for 32 hours with a ball mill, dry, and press-mold into green compact at 98 MPa pressure Then, this green compact is sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after sintering, the cutting edge portion is subjected to a honing process of R: 0.09 mm. Tool bases a to f made of TiCN-based cermet having a chip shape conforming to ISO standards / CNMG 120212 were formed.

Next, a normal chemical vapor deposition apparatus is used on the surfaces of the tool bases A to F and the tool bases a to f, and a Ti compound layer, a conventional (Ti, Cr) CN layer, a modified (Ti, Cr) CN layer) is formed by vapor deposition under the conditions shown in Table 3, Table 4, and Table 5 with the combinations and target layer thicknesses shown in Table 6, and further, the conditions shown in Table 3 and Table 6 are formed on the surface. The coated tools 1 to 13 of the present invention were produced by vapor-depositing an Al ₂ O ₃ layer with the target layer thickness shown in FIG.

For comparison purposes, a Ti compound layer as a hard coating layer and a conventional (Ti, Cr) CN layer are vapor-deposited with the combinations and target layer thicknesses shown in Table 7 under the conditions shown in Tables 3 and 4. Furthermore, comparative coated tools 1 to 13 were manufactured by vapor-depositing an Al ₂ O ₃ layer on the surface under the conditions shown in Table 3 and the target layer thickness shown in Table 7.

Next, an inclination angle number distribution graph was created for each of the conventional (Ti, Cr) CN layers constituting the hard coating layer of the above-described coated tool of the present invention and the comparative coated tool using a field emission scanning electron microscope.
That is, the inclination angle number distribution graph is set in a lens barrel of a field emission scanning electron microscope with the surface of the conventional (Ti, Cr) CN layer as a polished surface, and 70 ° on the polished surface. An electron backscatter diffraction imaging apparatus is irradiated by irradiating an electron beam with an acceleration voltage of 15 kV at an incident angle of 1 nA with an irradiation current of 1 nA on each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface. Using a 30 × 50 μm region at an interval of 0.1 μm / step, the inclination angle formed by the normal of the {112} plane, which is the crystal plane of the crystal grain, is measured with respect to the normal of the polished surface. Based on this measurement result, among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are divided for each pitch of 0.25 degrees, and the frequencies existing in each section are tabulated. Created by.
Next, as for the modified (Ti, Cr) CN layer constituting the hard coating layer of the coated tool of the present invention, a gradient angle number distribution graph was created using a field emission scanning electron microscope in the same manner as described above.
That is, the modified (Ti, Cr) CN layer is set in a lens barrel of a field emission scanning electron microscope in a state where the surface is a polished surface, and an acceleration voltage of 15 kV is applied to the polished surface at an incident angle of 70 degrees. Is irradiated with an electron current of 1 nA to each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface, and an electron backscatter diffraction image apparatus is used to form a 30 × 50 μm region. At an interval of 0.1 μm / step, an inclination angle formed by a normal line of the {111} plane that is a crystal plane of the crystal grain is measured with respect to a normal line of the surface polished surface, and based on the measurement result, Among the measured inclination angles, the measurement inclination angles in the range of 0 to 45 degrees were divided for each pitch of 0.25 degrees, and the frequency existing in each section was totaled.
Furthermore, for the conventional (Ti, Cr) CN layer constituting the hard coating layer of the comparative coated tool, the frequency ratio of the highest peak within the range of 0 to 10 degrees on the {111} plane is described above for reference. Was measured in the same manner.

  Table 6 shows the frequency ratio of the highest peak of the {112} plane of the conventional (Ti, Cr) CN layer and the peak ratio of the highest peak of the {111} plane of the modified (Ti, Cr) CN layer. (For reference, Table 7 also shows the frequency ratio of the highest peak of the {111} plane of the conventional (Ti, Cr) CN layer).

As shown in Table 6, the frequency ratio of the highest peak of the {112} plane of the conventional (Ti, Cr) CN layer of the present coated tools 1 to 13 and the modification of the present coated tools 1 to 13 (Ti, The frequency ratio of the highest peak of the {111} plane of the Cr) CN layer is 45% or more.
On the other hand, as shown in Table 7, although the frequency ratio of the highest peak of the {112} plane of the conventional (Ti, Cr) CN layer of the comparative coated tools 1 to 13 is 45% or more, the conventional The frequency ratio of the highest peak on the {111} plane of the (Ti, Cr) CN layer is less than 45%.

Further, for the above-described coated tools 1 to 13 and comparative coated tools 1 to 13 described above, the constituent layers of the hard coating layer were observed using an electron beam microanalyzer (EPMA) and an Auger spectroscopic analyzer (longitudinal section of the layer). The former consists of a Ti compound layer having substantially the same composition as the target composition, a conventional (Ti, Cr) CN layer and a modified (Ti, Cr) CN layer, and the latter also has a target composition. It was confirmed to be composed of a Ti compound layer having substantially the same composition and a conventional (Ti, Cr) CN layer. Moreover, when the thickness of the constituent layer of the hard coating layer of these coated tools was measured using a scanning electron microscope (similarly longitudinal section measurement), the average layer thickness (5 The average value of point measurement) was shown. As hard coating layer, in further coated tool coated with the Al ₂ O ₃ layer, the Al ₂ O ₃ layer showed the target layer substantially the same average layer thickness and the thickness (average value of five point measurement).

Next, in the state where each of the above various coated tools is screwed to the tip of the tool steel tool with a fixing jig, the present coated tools 1 to 13 and the comparative coated tools 1 to 13 are as follows:
Work material: JIS · SCM440 lengthwise equidistant 4 vertical grooved round bar,
Cutting speed: 400 m / min,
Cutting depth: 1.5 mm,
Feed: 0.3 mm / rev,
Cutting time: 8 minutes,
Wet intermittent high-speed cutting test (normal cutting speed is 250 m / min) of alloy steel under the above conditions (referred to as cutting condition A),
Work material: JIS · S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 400 m / min,
Cutting depth: 1.5 mm,
Feed: 0.35 mm / rev,
Cutting time: 10 minutes,
Wet intermittent high-speed cutting test (normal cutting speed is 300 m / min) of carbon steel under the conditions (referred to as cutting condition B),
Work material: JIS / FCD450 lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 400 m / min,
Cutting depth: 1.5 mm,
Feed: 0.25 mm / rev,
Cutting time: 8 minutes,
Wet intermittent high-speed cutting test of ductile cast iron under the above conditions (referred to as cutting condition C) (normal cutting speed is 250 m / min),
And
In any cutting test (using water-soluble cutting oil), the flank wear width of the cutting edge was measured. The measurement results are shown in Table 8.

  From the results shown in Tables 6 to 8, all of the present coated tools 1 to 13 have a frequency ratio of the highest peak of the {112} plane of the conventional (Ti, Cr) CN layer of the hard coating layer of 45% or more. This has excellent high-temperature strength, and the frequency ratio of the highest peak of the {111} plane of the modified (Ti, Cr) CN layer is 45% or more, which is excellent high-temperature strength, high-temperature hardness and Because of its heat resistance, it has high heat strength, high temperature hardness, and heat resistance, which is superior in hard coating layer even in high-speed intermittent cutting of various steels and cast irons that are accompanied by large heat generation and are repeatedly subjected to large impact and mechanical loads. As a result, the hard coating layer exhibits excellent chipping resistance and wear resistance, whereas the hard coating layer does not have a modified (Ti, Cr) CN layer. ~ 13 is high speed In secondary cutting, the hard coating layer has insufficient high-temperature strength and heat resistance, causing chipping in the hard coating layer, or due to the occurrence of thermoplastic deformation or uneven wear. It is very inferior and it is clear that the service life is reached in a relatively short time.

  As described above, the coated tool of the present invention is not only continuous and intermittent cutting under normal conditions such as various steels and cast irons, but also generates a large amount of heat and has a large impact and mechanical load on the cutting edge. Even in high-speed intermittent cutting, the hard coating layer exhibits excellent chipping resistance and wear resistance, and exhibits excellent cutting performance over a long period of time. It can respond satisfactorily to the reduction in cost, energy saving, and cost reduction.

It is a schematic explanatory drawing which shows the measurement range of the inclination angle of the {112} plane of the crystal grain in the conventional (Ti, Cr) CN layer which comprises a hard coating layer. It is a schematic explanatory drawing which shows the measurement range of the inclination angle of the {111} plane of the crystal grain in the modification | reformation (Ti, Cr) CN layer which comprises a hard coating layer. It is an inclination angle number distribution graph of the {112} plane of the conventional TiCN layer which comprises the hard coating layer of this invention coated tool 5. It is an inclination angle number distribution graph of the {111} plane of the modified (Ti, Cr) CN layer constituting the hard coating layer of the present coated tool 5. It is an inclination angle number distribution graph of the {111} plane of the conventional (Ti, Cr) CN layer constituting the hard coating layer of the comparative coating tool 5.

Claims (2)

At least a Ti compound layer and Ti and Cr carbonitride as a hard coating layer having a total average layer thickness of 4 to 20 μm on the surface of the tool base composed of tungsten carbide base cemented carbide or titanium carbonitride base cermet In a surface-coated cutting tool in which a material layer is formed by vapor deposition,
(A) The Ti compound layer is composed of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer,
(B) At least one of the Ti and Cr carbonitride layers has an average layer thickness of 2 to 15 μm, and
When represented by composition formula: (Ti _1-X Cr _X ) CN, it is a carbonitride layer of Ti and Cr that satisfies X: 0.12-0.2 in atomic ratio,
Further, by using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the normal line of the surface polishing surface is The inclination angle formed by the normal line of the {111} plane, which is the crystal plane of the crystal grain, is measured, and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is set every pitch of 0.25 degrees. In the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak is present in the inclination angle section in the range of 0 to 10 degrees, and within the range of 0 to 10 degrees. Is formed by a carbonitride layer of Ti and Cr showing an inclination angle distribution graph occupying a ratio of 45% or more of the entire frequency in the inclination angle distribution graph,
(C) Further, at least one of the Ti and Cr carbonitride layers has an average layer thickness of 2 to 15 μm, and
When represented by a composition formula: (Ti _1-Y Cr _Y ) CN, it is a carbonitride layer of Ti and Cr satisfying Y: 0.005 to 0.05 in atomic ratio,
Further, by using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the normal line of the surface polishing surface is The inclination angle formed by the normal of the {112} plane, which is the crystal plane of the crystal grain, is measured, and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is set every pitch of 0.25 degrees. In the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak is present in the inclination angle section in the range of 0 to 10 degrees, and within the range of 0 to 10 degrees. Is formed of Ti and Cr carbonitride layers showing an inclination angle distribution graph that occupies a ratio of 45% or more of the entire frequency in the inclination angle distribution graph.
A surface-coated cutting tool characterized by that.   The surface-coated cutting tool according to claim 1, wherein an aluminum oxide layer having an average layer thickness of 1 to 15 µm is further deposited on the surface of the hard coating layer having a total average layer thickness of 4 to 20 µm. .

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