JP5003308B2 - Surface coated cutting tool - Google Patents

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) Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer, carbon oxide (hereinafter referred to as TiC) layer formed by chemical vapor deposition , A lower layer consisting of a Ti compound layer having a total average layer thickness of 3 to 20 μm, and two or more of a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(B) an upper layer made of an aluminum oxide (Al ₂ O ₃ ) layer having an average layer thickness of 1 to 15 μm formed by chemical vapor deposition;
In a coated tool provided with the hard coating layer comprised by the above (a) and (b),
One of the Ti compound layers of (a) above is a cubic having an average layer thickness of 2.5 to 15 μm and existing within the measurement range of the surface polished surface using a field emission scanning electron microscope. Irradiating each crystal grain having a crystal lattice with an electron beam, and measuring an inclination angle formed by a normal of a {112} plane that is a crystal plane of the crystal grain with respect to a normal of the surface-polished surface; In the inclination angle number distribution graph formed by dividing the measurement inclination angles within the range of 0 to 45 degrees among the measurement inclination angles for each pitch of 0.25 degrees and totaling the frequencies existing in each section. In addition, the highest peak exists in the inclination angle section in the range of 0 to 10 degrees, and the total of the frequencies existing in the range of 0 to 10 degrees is a ratio of 45% or more of the entire degrees in the inclination angle frequency distribution graph. It has a vertically-grown crystal structure showing an inclination angle distribution graph That TiCN (hereinafter, shown in the conventional TiCN) layer,
It is known that this coated tool exhibits excellent chipping resistance in high-speed intermittent cutting of steel or cast iron.

In addition, on the surface of the tool base,
(A) One or more of a TiC layer having a granular crystal structure, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer formed by chemical vapor deposition, and a TiCN having a vertically grown crystal structure (hereinafter referred to as l-TiCN). And a lower layer comprising a Ti compound layer having a total average layer thickness of 3 to 20 μm,
(B) an upper layer composed of an Al ₂ O ₃ layer having an average layer thickness of 1 to 15 μm formed by chemical vapor deposition;
In a coated tool provided with the hard coating layer comprised by the above (a) and (b),
An average of 1 to 10 μm adjacent to the l-TiCN layer, in which a part of Ti in the l-TiCN layer is replaced with 10 atomic% or less of Cr (hereinafter referred to as a conventional (Ti, Cr) CN layer). It is known that by interposing with a layer thickness, excellent wear resistance is exhibited in high-speed cutting of steel or cast iron.
JP 2006-15426 A JP-A-10-244405

In recent years, the performance of cutting machines has been remarkable. On the other hand, there are strong demands for labor saving and energy saving in cutting, as well as high efficiency and low cost, and coating with both chipping resistance and wear resistance characteristics. Where a tool is desired, the above-mentioned conventional coated tool is provided with a conventional TiCN layer having a predetermined high-temperature strength as a lower layer and an Al ₂ O ₃ layer having excellent high-temperature hardness as an upper layer. Therefore, when this was used for high-speed intermittent cutting of steel or cast iron, there was no particular problem with the occurrence of chipping, but because the heat resistance of the conventional TiCN layer was not sufficient, thermoplastic deformation, uneven wear It was easy to generate | occur | produce, and it could not be said that it had the characteristic which was satisfactory about abrasion resistance.
Therefore, in order to improve the wear resistance of the conventional coated tool, it is conceivable to further provide the conventional (Ti, Cr) CN layer having excellent wear resistance as a constituent layer of the hard coating layer. The Ti, Cr) CN layer is subject to a large impact and mechanical load on the cutting edge, and furthermore, heat resistance is still insufficient in high-speed intermittent cutting with high heat generation, so uneven wear due to thermoplastic deformation occurs. As a result, it is very difficult to improve both the chipping resistance and the wear resistance of the coated tool provided with the conventional TiCN layer and the conventional (Ti, Cr) CN layer. It was.

  From the above viewpoints, the present inventors conducted research on the constituent layers of the hard coating layer in order to improve the wear resistance as well as the chipping resistance of the hard coating layer of the conventional coated tool described above. I got the knowledge.

(A) The conventional TiCN layer of the Ti compound layer constituting the lower layer of the hard coating layer of the conventional coated tool is, for example, a normal chemical vapor deposition apparatus.
Reaction gas composition _{(volume%): TiCl 4: 2~10%} , CH 3 CN: 0.5~3%, N 2: 10~30%, H 2: remainder,
Reaction atmosphere temperature: 800-920 ° C.
Reaction atmosphere pressure: 6-20 kPa,
And the content ratio of the film formation start point and film formation end point of the CH ₃ CN constituting the reaction gas is adjusted in accordance with the layer thickness within the above content range, TiCN layer under the condition that the content ratio of CH ₃ CN is gradually or intermittently increased from the film formation start time when the content ratio is lowered to the film formation end time when the content ratio is relatively increased It can be formed by evaporating.

(B) And, the conventional TiCN layer is a cubic that exists within the measurement range of the surface polished surface by using a field emission scanning electron microscope, as schematically shown in FIGS. 1 (a) and 1 (b). Irradiating each crystal grain having a crystal lattice with an electron beam, and measuring an inclination angle formed by a normal of a {112} plane that is a crystal plane of the crystal grain with respect to a normal of the surface-polished surface; In the inclination angle number distribution graph formed by dividing the measurement inclination angles within the range of 0 to 45 degrees among the measurement inclination angles for each pitch of 0.25 degrees and totaling the frequencies existing in each section. In addition, the highest peak exists in the inclination angle section in the range of 0 to 10 degrees, and the total of the frequencies existing in the range of 0 to 10 degrees is a ratio of 45% or more of the entire degrees in the inclination angle frequency distribution graph. The inclination angle number distribution graph which occupies (see Fig. 3)

(C) Further, when forming the conventional TiCN layer, the content of CH ₃ CN in the reaction gas is set to 0.5 to 3%, and the film formation start time corresponding to the layer thickness is within the content range. And adjusting the CH ₃ CN content at the end of film formation, and gradually increasing the CH ₃ CN content from the start of film formation to the end of film formation (that is, the thinner the layer, the more the film is formed). determine the amount of of CH 3 _CN beginning and the deposition end to a lower side within the 0.5% to 3%, the layer thickness of the deposition starting point and the deposition end point in the middle of CH 3 _CN The content is an intermediate content within the above range, and the further the layer thickness, the higher the content range of the CH ₃ CN, the higher the content range (ie, the CH ₃ CN at the end of film formation). Content)-(value of CH ₃ CN content at the start of film formation)) 1 ± 0.15% is desirable, and when the content width is less than 0.85%, the sum of the frequencies of the highest peak existing within the range of 0 to 10 degrees is the entire frequency in the gradient angle distribution graph. Therefore, when the content width exceeds 1.15%, the tilt angle section where the highest peak appears is not obtained. Is not within the range of 0 to 10 degrees, and the TiCN layer cannot secure the desired excellent high-temperature strength.

(D) On the other hand, the conventional (Ti, Cr) CN layer is, for example, a normal chemical vapor deposition apparatus.
Reaction gas composition: by _{volume%, TiCl 4: 3~10%,} CrF 5: 0.1~0.4%, CH 3 CN: 0.5~3%, N 2: 20~40%, H 2: remaining,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 6-20 kPa,
It is formed by vapor deposition under the conditions (called normal conditions)
Reaction gas composition: by _{volume%, TiCl 4: 1~5%,} CrCl 3: 0.7~2.5%, CH 3 CN: 3~6%, N 2: 20~40%, HCl: 0.5 ~2%, H _2: remainder,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 5 to 20 kPa,
Compared with the above conditions, that is, the above normal conditions, a small amount of CrCl ₃ and HCl were added instead of CrF ₅ which is one of the reaction gas components, and the content ratio of TiCl ₄ and CH ₃ CN was increased. Vapor deposition with conditions,
Composition formula: (Ti _1-X Cr _X ) CN (wherein, in atomic ratio, X: 0.12 to 0.20),
When the (Ti, Cr) CN layer satisfying the above is formed, the resulting (Ti, Cr) CN layer (hereinafter referred to as a modified (Ti, Cr) CN layer) is the conventional (Ti, Cr) CN layer described above. The crystal structure of the NaCl type face centered cubic crystal in which the constituent atoms composed of Ti, Cr, carbon (C), and nitrogen (N) are respectively present at the lattice points. It should have heat resistance that is much better than that of the Cr) CN layer.

(E) And, for the conventional (Ti, Cr) CN layer and 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 each pitch of 0.25 degrees and the inclination angle number distribution graph is formed by counting the frequencies existing in each division, the conventional (Ti, Cr) As illustrated in FIG. 5, the CN layer shows an unbiased inclination angle number distribution graph in the range of the measured inclination angle of the {111} plane in the range of 0 to 45 degrees, whereas the modification ( As illustrated in FIG. 4, the Ti, Cr) CN layer has a sharp peak at a specific position in the tilt angle section. A peak appears, and in such a case, cooling cracks are uniformly dispersed in the modified (Ti, Cr) CN layer, thereby modifying the (Ti, Cr) CN layer due to an increase in Cr content. In addition, the sharp maximum peak has a height that appears in the tilt angle section of the horizontal axis of the graph and the position of the tilt angle section in the modified (Ti, Cr) CN layer. It changes by adjusting the content ratio.

(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. In the gradient angle distribution graph of the modified (Ti, Cr) CN layer, a sharp maximum peak appears in the range of 0 to 10 degrees of the tilt angle section, and the range of 0 to 10 degrees In the modified (Ti, Cr) CN layer, the frequency ratio existing in the tilt angle frequency distribution graph occupies a ratio of 45% or more of the entire frequency in the tilt angle frequency distribution graph. Even if the Cr content ratio is out of the lower range or higher range, the sharp peak in the tilt angle number distribution graph is out of the range of 0 to 10 degrees of the tilt angle section, and Within the range of 0 to 10 degrees The frequency ratio is also less than 45%. In this case, not only can the heat resistance improvement effect be further improved, but also the decrease in high-temperature strength due to the increased Cr content ratio should be suppressed by uniform distribution of cooling cracks. What you can't do.
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) Therefore, one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer as a hard coating layer on the surface of the cutting tool base. And a modified (Ti, Cr) CN layer, and at least one of the Ti compound layers is the conventional TiCN layer, thereby increasing the high temperature strength of the entire hard coating layer. Since the wear resistance can be greatly improved at the same time, the coated tool with the hard coating layer deposited thereon was used for high-speed intermittent cutting with high heat generation and high mechanical and impact load. Even in this case, excellent chipping resistance is exhibited, and excellent wear resistance is exhibited over a long period of time.

This invention has been made based on the above findings,
“(1) At least a Ti compound layer and a carbonitriding of 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 composed of a WC-based cemented carbide or TiCN-based 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 TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer,
(B) At least one of the Ti compound layers has an average layer thickness of 2 to 10 μm, and a cubic crystal existing within the measurement range of the surface polished surface using a field emission scanning electron microscope. The crystal grains having a lattice are irradiated with an electron beam, and 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 surface-polished surface. In the inclination angle number distribution graph formed by dividing the measured inclination angles within the range of 0 to 45 degrees out of the inclination angles for each pitch of 0.25 degrees and totaling the frequencies existing in each section, 0 The highest peak exists in the inclination angle section within the range of -10 degrees, and the total of the frequencies existing within the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire degrees in the inclination angle frequency distribution graph. Ti carbonitride layer showing an inclination angle distribution graph It is a conventional TiCN layer),
(C) The Ti and Cr carbonitride layer 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. Ti and Cr carbonitride layer (modified (Ti, Cr) CN layer) showing a tilt angle frequency distribution graph in which the total number of frequencies present in the tilt angle frequency distribution graph accounts for 45% or more of the total frequency in the tilt angle frequency distribution graph Is,
A surface-coated cutting tool (coated tool).
(2) The Al ₂ O ₃ layer having an average layer thickness of 1 to 15 μm is further formed by vapor deposition on the surface of the hard coating layer having a total average layer thickness of 4 to 20 μm. 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 Ti compound layer composed of one or more of TiC layer, TiN layer, TiCN layer, TiCO layer, and TiCNO layer (Note that the conventional TiCN layer is described later (b ))) Itself has a predetermined high temperature strength, and the presence of this provides the hard coating layer with a high temperature strength, as well as a tool base and a conventional TiCN layer or modified (Ti, Cr) CN layer. Any of the above has an effect of improving the adhesion of the hard coating layer to the tool substrate, but if the total average layer thickness is less than 4 μm, the above-mentioned effect cannot be sufficiently exhibited, When the total average layer thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation by high-speed intermittent cutting, and this causes uneven wear. Therefore, the total average layer thickness of the Ti compound layer is set to 4 to 20 μm. I tried.

(B) Conventional TiCN layer As described above, the conventional TiCN layer of the Ti compound layer is formed, for example, with the content ratio of CH ₃ CN as a component of the reaction gas being 0.5 to 3%. In an inclination angle distribution graph in which the frequency of the inclination angle formed by the normal of the {112} plane is tabulated by gradually increasing the content of CH ₃ CN from the start time to the film formation end time, 0 to The highest peak is present in the inclination angle section within the range of 10 degrees, and the total of the frequencies existing within the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire degrees in the inclination angle frequency distribution graph, In addition, a conventional TiCN layer having a vertically elongated crystal structure and having excellent high-temperature strength can be formed by vapor deposition. However, if the average layer thickness is less than 2 μm, the desired excellent high-temperature strength improvement effect can be exhibited. Can't On the other hand, if the average layer thickness exceeds 10 μm, thermoplastic deformation that causes uneven wear tends to occur, and wear accelerates. Therefore, the average layer thickness was set to 2 to 10 μm.

(C) Modified (Ti, Cr) CN layer Composition formula: (Ti _1-X Cr _X ) For the modified (Ti, Cr) CN layer represented by CN, the Cr content ratio (X value) in the layer Is an atomic ratio occupying the total amount of Ti, and is 0.12 to 0.2, and has a vertically elongated crystal structure and totals the inclination angles formed by the normal of the {111} plane In the inclination angle distribution graph, the highest peak is present in the inclination angle section in the range of 0 to 10 degrees, and the total of the frequencies existing in the range of 0 to 10 degrees is the entire frequency in the inclination angle distribution graph. It is possible to form a modified (Ti, Cr) CN layer occupying a proportion of 45% or more of this, but this modified (Ti, Cr) CN layer has excellent heat resistance and further has uniform cooling cracks. Of the layer by increasing the Cr content. Because it can prevent a decrease in temperature strength, exhibit excellent high temperature strength, significant improvements in or wear resistance chipping resistance only is achieved.
Therefore, even if the content ratio is less than 0.12 or more than 0.2, the effect of improving the high temperature strength and heat resistance cannot be expected. In high-speed intermittent cutting with a heavy load, both chipping resistance and wear resistance are inferior due to the occurrence of thermoplastic deformation and uneven wear.
As in the case of conventional TiCN, if the average layer thickness is less than 2 μm, excellent high temperature strength and heat resistance improvement effect cannot be expected. On the other hand, if the average layer thickness exceeds 15 μm, it causes uneven wear. Therefore, the average layer thickness was determined to be 2 to 15 μm.

  In addition, regarding C and N, which are constituents other than Ti and Cr in the modified (Ti, Cr) CN layer, the C component improves the hardness of the layer, and the N component improves high temperature strength. By coexisting these two components, it becomes a carbonitride layer having high hardness and excellent strength. Therefore, the content ratio of the N component in the layer is the total amount with the C component. If the ratio (= N / (C + N)) is less than 0.35 (however, the atomic ratio), the desired strength cannot be ensured. On the other hand, if the content ratio exceeds 0.55, relatively C Since the content ratio of the component becomes too small and the desired high hardness cannot be obtained, the content ratio of the N component with respect to the total amount with the C component in the modified (Ti, Cr) CN layer (= N / (C + N) ) May be 0.35 to 0.55 in atomic ratio Masui.

In the present invention, the hard coating layer is formed of at least one of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer. Layer is the conventional TiCN layer) and the modified (Ti, Cr) CN layer, but the conventional TiCN layer and the modified (Ti, Cr) CN layer are adjacent to each other. It is not always necessary to provide the TiCN layer and the modified (Ti, Cr) CN layer as the hard coating layer. As a result, there is no significant change in the function and effect of the hard coating layer as a whole.

(D) Al ₂ O ₃ layer In order to improve the wear resistance of the coated tool, it is conventionally well known that an Al ₂ O ₃ layer is provided as a surface constituent layer of the hard coating layer. By further forming an Al ₂ O ₃ layer on the surface of the Ti compound layer or the modified (Ti, Cr) CN layer, the surface of the hard coating layer can be composed of the Al ₂ O ₃ layer. The wear resistance of the coated tool of the present invention can be further improved.
As 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, Izu these crystal structures The Al ₂ O ₃ layer may be vapor deposited and the crystal structure is not particularly limited.
However, when the Al ₂ O ₃ layer is formed 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 large, chipping is likely to occur. Therefore, the average layer thickness needs to be 1 to 15 μm.

  Furthermore, for the purpose of identification before and after the use of the cutting tool, for example, a TiN layer having a golden color tone can be further vapor-deposited as the outermost surface layer. An average layer thickness of 0.1-1 μm is sufficient.

  The coated tool of the present invention has at least one Ti compound layer that constitutes a hard coating layer even in high-speed intermittent cutting of steel, cast iron or the like that is accompanied by high heat generation and repeatedly repeatedly undergoes large impact and mechanical loads. Has a high temperature strength because it is conventionally composed of a TiCN layer, and a modified (Ti, Cr) CN layer has an excellent heat resistance in addition to an excellent high temperature strength, resulting in a hard coating. The layer will exhibit excellent chipping resistance and excellent wear resistance over 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 into the blending composition shown in Table 1, further added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and then formed into a 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 with a ball mill for 24 hours, dry, and press-mold into a 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, on the surfaces of these tool bases A to F and tool bases a to f, an ordinary chemical vapor deposition apparatus is used, and a hard coating layer is formed as a Ti compound layer (of which at least one layer is a conventional TiCN layer) and a modification. A (Ti, Cr) CN layer is formed by vapor deposition under the conditions shown in Table 3, Table 4, and Table 6 with the combinations and target layer thicknesses shown in Table 7, and the surface is shown in Table 3. The coated tools 1 to 13 of the present invention were manufactured by vapor-depositing Al ₂ O ₃ layers under the conditions and the target layer thicknesses shown in Table 7.

For comparison purposes, a Ti compound layer (at least one of which is a conventional TiCN layer) and a conventional (Ti, Cr) CN layer as hard coating layers and the conditions shown in Table 3, Table 4, and Table 5 are used. Comparison is made by vapor-depositing with the combinations and target layer thicknesses shown in Table 8 and further depositing an Al ₂ O ₃ layer on the surface with the conditions shown in Table 3 and the target layer thicknesses shown in Table 8. Coated tools 1-13 were produced.

Next, an inclination angle number distribution graph was created using a field emission scanning electron microscope for the conventional TiCN layer constituting the hard coating layer of the above-described coated tool of the present invention and the comparative coated tool.
That is, the tilt angle number distribution graph is set in a lens barrel of a field emission scanning electron microscope with the surface of the conventional TiCN layer as a polished surface, and 15 kV at an incident angle of 70 degrees on the polished surface. A 30 × 50 μm electron backscatter diffraction image apparatus was used to irradiate an electron beam with an acceleration voltage 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 polished surface. Is measured at an interval of 0.1 μm / step with respect to the normal of the surface-polished surface and the inclination angle formed by the normal of the {112} plane which is the crystal plane of the crystal grain. Based on the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees were divided for each pitch of 0.25 degrees, and the frequencies existing in each section were totaled.
Next, for the modified (Ti, Cr) CN layer that constitutes the hard coating layer of the coated tool of the present invention and the conventional (Ti, Cr) CN layer that constitutes the hard coating layer of the comparative coated tool, An inclination angle number distribution graph was prepared using an emission scanning electron microscope.
That is, the surface of the modified (Ti, Cr) CN layer and the conventional (Ti, Cr) CN layer is used as a polished surface, and is set in a lens barrel of a field emission scanning electron microscope. An electron backscatter diffraction image apparatus by irradiating an electron beam with an acceleration voltage of 15 kV at an incident angle of 1 degree 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. Is used to measure the inclination angle formed by the normal of the {111} plane, which is the crystal plane of the crystal grain, with respect to the normal of the polished surface at an interval of 0.1 μm / step in a 30 × 50 μm region Based on the measurement results, the measurement inclination angles within the range of 0 to 45 degrees out of the measurement inclination angles are divided for each pitch of 0.25 degrees, and the frequencies existing in each division are tabulated. Created by.

An inclination angle number distribution graph obtained for the {112} plane of the conventional TiCN layer of the present coated tool 5 is shown in FIG. 3, and the {111} plane of the modified (Ti, Cr) CN layer of the present coated tool 5 An inclination angle number distribution graph obtained with respect to is shown in FIG. 4, and an inclination angle number distribution graph obtained with respect to the {111} plane of the conventional (Ti, Cr) CN layer of the comparative coated tool 5 is shown in FIG.
Further, the inclination angle where the highest peak exists in the inclination angle number distribution graph obtained for the {112} plane of the conventional TiCN layer, the {111} plane of the conventional (Ti, Cr) CN layer and the modified (Ti, Cr) CN layer. Tables 7 and 8 show the frequency ratio of the classification and the highest peak, respectively.

As shown in Table 7, the highest peak frequency ratio of the {112} plane of the conventional TiCN layer of the present coated tools 1 to 13 and the highest peak frequency ratio of the {111} plane of the modified (Ti, Cr) CN layer. Indicates 45% or more.

On the other hand, as shown in Table 8, although the frequency ratio of the highest peak of the {112} plane of the conventional TiCN layer of the comparative coated tools 1 to 13 is 45% or more, the conventional (Ti, Cr) The frequency ratio of the highest peak on the {111} plane of the CN layer is less than 30%.

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 is composed of a Ti compound layer having substantially the same composition as the target composition, a conventional TiCN layer and a modified (Ti, Cr) CN layer, and the latter is also substantially the same as the target composition. It was confirmed that the Ti compound layer had a conventional TiCN layer 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. For the Al ₂ O ₃ layer formed by vapor deposition as the surface layer, the average layer thickness (average value of five-point measurement) substantially the same as the target layer thickness was measured.

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: 0.24 mm / rev,
Cutting time: 8 minutes,
Wet high-speed intermittent cutting test (normal cutting speed is 250 m / min) of alloy steel under the following conditions (referred to as cutting condition A),
Work material: JIS · S40C lengthwise equal length 4 round bar with round groove,
Cutting speed: 400 m / min,
Cutting depth: 1.5 mm,
Feed: 0.35 mm / rev,
Cutting time: 10 minutes,
Wet high-speed intermittent cutting test of carbon steel under the above conditions (referred to as cutting condition B) (normal cutting speed is 250 m / min),
Work material: JIS / FCD350 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 high-speed intermittent cutting test (normal cutting speed is 250 m / min) under the conditions (referred to as cutting condition C),
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 9.

  From the results shown in Tables 7 to 9, the coated tools 1 to 13 of the present invention all have a high peak frequency ratio of 45% or more of the {112} plane of the conventional TiCN layer of the hard coating layer, which is excellent at high temperature. It has high 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 has excellent high temperature strength and excellent heat resistance. The hard coating layer has excellent high-temperature strength and heat resistance even in high-speed intermittent cutting such as steel and cast iron, which are accompanied by large impacts and mechanical loads. As a result, the hard coating layer is excellent. In the conventional coated tools 1 to 13 that do not have a modified (Ti, Cr) CN layer as a hard coating layer, while exhibiting excellent chipping resistance and excellent wear resistance, the conventional (Ti, Cr) CN {111 of layers Since the frequency ratio of the highest peak of the surface is less than 30%, the heat resistance of the hard coating layer is particularly insufficient in high-speed intermittent cutting, and the resistance of the hard coating layer is increased due to the occurrence of uneven wear due to thermoplastic deformation. It is apparent that the wear life is inferior or that the service life is reached in a relatively short time due to the occurrence of chipping.

  As described above, the coated tool of the present invention not only performs continuous cutting and intermittent cutting under normal conditions such as various steels and cast irons, but also generates a large amount of heat, and also has a large impact / mechanical effect on the cutting edge. Even in high-speed interrupted cutting with high load, the hard coating layer exhibits not only excellent chipping resistance but also excellent wear resistance, and exhibits excellent cutting performance over a long period of time. In addition, it is possible to sufficiently satisfy the labor-saving and energy-saving of the cutting process and the 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 TiCN 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 a Ti and Cr carbonitride as a hard coating layer having a total average layer thickness of 4 to 20 μm on the surface of a tool base composed of tungsten carbide base cemented carbide or titanium carbonitride base cermet In a surface-coated cutting tool in which a 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 compound layers has an average layer thickness of 2 to 10 μm, and a cubic crystal existing within the measurement range of the surface polished surface using a field emission scanning electron microscope. The crystal grains having a lattice are irradiated with an electron beam, and 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 surface-polished surface. In the inclination angle number distribution graph formed by dividing the measured inclination angles within the range of 0 to 45 degrees out of the inclination angles for each pitch of 0.25 degrees and totaling the frequencies existing in each section, 0 The highest peak exists in the inclination angle section within the range of -10 degrees, and the total of the frequencies existing within the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire degrees in the inclination angle frequency distribution graph. Ti carbonitride layer showing an inclination angle distribution graph Yes,
(C) The Ti and Cr carbonitride layer 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 a Ti and Cr carbonitride layer 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 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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