JP4193053B2 - Surface-coated cermet cutting tool that exhibits excellent chipping resistance with a hard coating layer in heavy cutting - Google Patents

Description

  This invention is a surface-coated cermet cutting tool (hereinafter referred to as coated cermet) that exhibits excellent chipping resistance with a hard coating layer, particularly in heavy cutting with high mechanical and thermal shock such as various steels and cast iron. Tool).

Conventionally, generally on the surface of a substrate (hereinafter collectively referred to as a tool substrate) composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet. ,
(A) Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer, oxide (hereinafter referred to as TiO) layer, Ti compound layer composed of one or more of a carbon oxide (hereinafter referred to as TiCO) layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer and having an overall average layer thickness of 3 to 20 μm ,
(B) having an average layer thickness of 1 to 30 μm and a composition formula: (Al _1-Y Cr _Y ) ₂ O ₃ (where Y is an atomic ratio, Y: 0.03 to 0.20),
A solid solution oxide of Al and Cr satisfying the following conditions (hereinafter referred to as vapor-deposited (Al, Cr) ₂ O ₃ ) layer:
A coated cermet tool formed by chemical vapor deposition of the hard coating layer composed of (a) and (b) above is known, and this coated cermet tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is well known to be used in

In general, the Ti compound layer and the vapor deposition (Al, Cr) ₂ O ₃ layer constituting the hard coating layer of the above coated cermet tool have a granular crystal structure, and further, the TiCN layer constituting the Ti compound layer is provided. For the purpose of improving the strength of the layer itself, it is formed by chemical vapor deposition in a medium temperature range of 700 to 950 ° C. using a mixed gas containing organic carbonitride as a reaction gas in a normal chemical vapor deposition apparatus. It is also known to have a vertically elongated crystal structure.
Japanese Patent Publication No.58-53065

In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting work. With this, cutting works under heavy cutting conditions such as higher cutting depth and higher feed. However, in the conventional coated cermet tool described above, there is no problem when it is used for continuous cutting or intermittent cutting under normal conditions such as steel or cast iron. Is used for heavy cutting with high mechanical and thermal shock, the vapor deposition (Al, Cr) ₂ O ₃ layer that constitutes the hard coating layer is excellent due to the action of the Al component with a relatively large content. Although it has high-temperature hardness and heat resistance, it does not have sufficient high-temperature strength, so chipping (slight chipping) is likely to occur in the hard coating layer, resulting in a service life in a relatively short time. Is

In view of the above, the present inventors pay attention to the coated cermet tool in which the above-described vapor-deposited (Al, Cr) ₂ O ₃ layer constitutes a hard coating layer, and to improve the chipping resistance thereof. As a result of research,
On the surface of the tool base, the Ti compound layer is formed as a hard coating layer, and in place of the conventional vapor deposition (Al, Cr) ₂ O ₃ layer,
Composition _{formula: (Cr 1-X Al X} ) 2 O 3, ( provided that, X is atomic ratio, X: 0.3~0.45),
A solid solution oxide of Cr and Al satisfying the following conditions (hereinafter referred to as vapor-deposited (Cr, Al) ₂ O ₃ ) layer:
Then, the Ti compound is subjected to heat treatment at a temperature of 600 to 800 ° C. for 1 to 5 hours in a non-oxidizing atmosphere (for example, 1013 hPa hydrogen atmosphere or Ar atmosphere) or a vacuum atmosphere. There is no change in the layer, but phase separation occurs in the deposited (Cr, Al) ₂ O ₃ layer, and a solid solution oxide separation phase of Cr and Al containing Cr higher than that of Al [hereinafter referred to as high Cr- An Al oxide separated phase] and a Cr having a two-phase mixed structure consisting of a solid solution oxide separated phase of Al and Cr having a high Al content compared to Cr [hereinafter referred to as a high Al-Cr oxide separated phase] A heated two-phase separation oxide layer of Al (hereinafter referred to as a two-phase separation (Cr, Al) ₂ O ₃ layer) is formed. In the two-phase separation (Cr, Al) ₂ O ₃ layer, the high Cr—Al oxidation is performed. Excellent material separation phase due to high Cr content Has a high temperature strength, has excellent high-temperature hardness and heat resistance the high Al-Cr oxide isolation phase by the high content of Al, and the deposition (Cr, Al) ratio of the Cr component in the ₂ O ₃ layer is Since it is relatively high compared to the Al component, the ratio of the high Cr—Al oxide separated phase is higher than the ratio of the high Al—Cr oxide separated phase, and as a result, the overall Compared with the conventional vapor deposition (Al, Cr) ₂ O ₃ layer of the present invention, it has excellent high-temperature strength, and also has excellent high-temperature hardness and heat resistance. Therefore, the two-phase separation (Cr, Al) _The coated cermet tool formed with the ₂ O ₃ layer coexisting with the Ti compound layer as a hard coating layer is chipped to the cutting edge by heavy cutting such as high cutting and high feed with high mechanical and thermal shock. (Slight chipping) In comparison with the conventional coated cermet tools is to obtain a finding that comes to exhibit more excellent wear resistance.

The present invention has been made based on the above research results, and on the surface of a tool base composed of a WC-based cemented carbide or TiCN-based cermet,
(A) a Ti compound layer composed of one or more of a TiC layer, a TiN layer, a TiCN layer, a TiO layer, a TiCO layer, and a TiCNO layer, and having an overall average layer thickness of 3 to 20 μm,
(B) the composition _{formula: (Cr 1-X Al X} ) 2 O 3, ( provided that, X is atomic ratio, X: 0.30~0.45),
A vapor-deposited (Cr, Al) ₂ O ₃ layer that satisfies the following conditions: a two-phase mixed structure comprising a high Cr—Al oxide separated phase and a high Al—Cr oxide separated phase, and 1 to Two-phase-separated (Cr, Ai) ₂ O ₃ layers having an average layer thickness of 30 μm,
The present invention is characterized by a coated cermet tool which is formed by the hard coating layer constituted by the above (a) and (b) and exhibits excellent chipping resistance in heavy cutting processing.

The reason why the constituent layers of the hard coating layer of the coated cermet tool of the present invention are numerically limited as described above will be described below.
(A) X value of vapor-deposited (Cr, Al) ₂ O ₃ layer If the X value is less than 0.30 in terms of atomic ratio (hereinafter the same), the ratio of high Al—Cr oxide separated phase after heat treatment is high Cr—Al It becomes too small compared with the oxide separation phase, and the desired high-temperature hardness and heat resistance cannot be ensured for the two-phase separation (Cr, Al) ₂ O ₃ layer, so that the wear of the hard coating layer is promoted. On the other hand, if the X value exceeds 0.45, the ratio of the high Cr-Al oxide separated phase after the heat treatment is reduced, and the desired excellent high-temperature strength cannot be ensured. Therefore, the X value was set to 0.30 to 0.45.
(B) Overall average layer thickness of the Ti compound layer The Ti compound layer basically exists as a lower layer of the two-phase separation (Cr, Al) ₂ O ₃ layer, and has a hard coating layer due to its excellent strength. In addition to providing strength, the tool base and the two-phase-separated (Cr, Al) ₂ O ₃ layer are firmly adhered to each other, and thus have an effect of improving the adhesion of the hard coating layer to the tool base. If the total average layer thickness is less than 3 μm, the above-mentioned effect cannot be sufficiently exerted. On the other hand, if the total average layer thickness exceeds 20 μm, it is easy to cause thermoplastic deformation especially in heavy cutting with high heat generation. Since this causes uneven wear, the overall average layer thickness was determined to be 3 to 20 μm.
(C) 2-phase separation (Cr, _Al) 2 _{O 3} Average layer thickness 2 phase separation of layers (Cr, _Al) in the 2 _{O 3} layer, excellent high-temperature strength caused by high Cr-Al oxide separate phase, In addition, due to the excellent high temperature hardness and heat resistance due to the high Al-Cr oxide separated phase, the hard coating layer exhibits excellent wear resistance over a long period of time without heavy chipping even in heavy cutting conditions. However, if the average layer thickness is less than 1 μm, the above-mentioned effect cannot be sufficiently exerted. On the other hand, if the average layer thickness exceeds 30 μm, chipping tends to occur. The average layer thickness was determined to be 1-30 μm.

The covered cermet tool of the present invention has a two-phase separation (Cr, Al) ₂ O ₃ layer that forms a hard coating layer even in heavy cutting of various steels and cast irons with high mechanical and thermal shock. Since it has excellent high-temperature strength and also has high-temperature hardness and heat resistance, it exhibits excellent wear resistance over a long period of time without occurrence of chipping in the hard coating layer.

  Next, the coated cermet 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 diameter of 1 to 3 μm are prepared as raw material powders. These raw material powders were blended into the composition shown in Table 1, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and pressed into a green compact with a predetermined shape at a pressure of 98 MPa. The green compact was vacuum sintered at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa. After sintering, the cutting edge portion was R: 0.07 mm honing By performing the processing, tool bases A to F made of a WC-base cemented carbide having a throwaway tip shape specified in ISO · CNMG120408 were manufactured.

In addition, as raw material powders, TiCN (mass ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder, all having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and pressed into a compact at a pressure of 98 MPa. The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after the sintering, the cutting edge portion was subjected to a honing process of R: 0.07 mm. Tool bases a to f made of TiCN-based cermet having a standard / CNMG12041 chip shape were formed.

Next, a normal chemical vapor deposition apparatus was used on the surfaces of these tool bases A to F and tool bases a to f. First, Table 3 (l-TiCN in Table 3 is described in JP-A-6-8010). The TiCN layer and the vapor deposition (Cr are shown under the conditions shown in the conditions for forming a TiCN layer having a vertically grown crystal structure, and other conditions for forming a normal granular crystal structure). , Al) ₂ O ₃ -A to D, a hard coating layer composed of any one of the layers shown in Table 4 is deposited and formed with the target layer thickness shown in Table 4 and then 1013 hPa (1 atm) ) In a hydrogen atmosphere at a temperature of 700 ° C. under the condition of holding for a predetermined time within a range of 1 to 5 hours, and each of the deposited (Cr, Al) ₂ O ₃ -A to D layers is phase-separated. High Cr-Al oxide separated phase and high A 2-phase separation with a 2-phase mixed structure consisting -Cr oxide isolation phase (Cr, _Al) 2 _{O 3} layer [Table 4 heat treatment, vapor deposition _{(Cr, Al)} indicated by 2 O 3 -A~D] and By doing this, this invention coated cermet tool 1-13 was manufactured, respectively.

Further, for comparison purposes, as shown in Table 5, instead of the above-described deposition (Cr, Al) ₂ O ₃ -A to D layers, deposition (Al, Cr) ₂ O was performed under the conditions shown in Table 3. _{3−a to} d layers are formed, respectively, and the hard coating layer [the deposited (Al, Cr) ₂ O ₃ −a to d layers] is subjected to the same conditions except that the heat treatment under the above conditions is not performed. Conventionally coated cermet tools 1 to 13 were produced.

  Regarding the constituent layers of the hard coating layers of the above-described coated cermet tools 1 to 13 of the present invention and the conventional coated cermet tools 1 to 13, the thicknesses thereof were measured using a scanning electron microscope (longitudinal section measurement). The average layer thickness (average value of 5-point measurement) substantially the same as the target layer thickness was shown.

Moreover, the two-phase separation (Cr, Al) ₂ O ₃ layer of the hard coating layer of the above-described coated cermet tools 1 to 13 and the vapor deposition (Al, Cr) ₂ O ₃ layer of the conventional coated cermet tools 1 to 13 Were observed with a high-resolution electron microscope using a post-column type energy filter, respectively, and in the two-phase separated (Cr, Al) ₂ O ₃ layer, both the high Cr-Al oxide separated phase and the high Al -A two-phase mixed structure composed of a Cr oxide separated phase was exhibited, and the vapor-deposited (Al, Cr) ₂ O ₃ layer exhibited a single-phase structure composed of a solid solution.

Next, with respect to the present invention coated cermet tools 1 to 13 and the conventional coated cermet tools 1 to 13 in a state where any of the above various coated cermet tools is screwed to the tip of the tool steel tool with a fixing jig. ,
Work material: JIS · SCM440 lengthwise equidistant 4 vertical grooved round bar,
Cutting speed: 150 m / min,
Incision: 9mm,
Feed: 0.60mm / rev,
Cutting time: 5 minutes
Dry interrupted high cutting test of alloy steel under the conditions of (normal cutting amount is 4mm),
Work material: JIS / S45C round bar,
Cutting speed: 200 m / min,
Incision: 4mm,
Feed: 0.80mm / rev,
Cutting time: 5 minutes
Dry continuous high feed cutting test of carbon steel under the conditions (normal feed is 0.40 mm / rev),
Work material: JIS / FC300 round bar,
Cutting speed: 250 m / min,
Incision: 6mm,
Feed: 0.40mm / rev,
Cutting time: 10 minutes,
The dry continuous high-cutting cutting test (normal cutting amount is 3 mm) of cast iron under the above conditions was performed, and the flank wear width of the cutting blade was measured in any cutting test. The measurement results are shown in Table 6.

表４〜６に示される結果から、本発明被覆サーメット工具１〜１３は、高い機械的熱的衝撃を伴なう各種の鋼や鋳鉄の重切削加工でも、硬質被覆層にチッピングの発生なく、硬質被覆層がすぐれた耐摩耗性を発揮するのに対して、従来被覆サーメット工具１〜１３においては、いずれも硬質被覆層にチッピングは発生し、これが原因で比較的短時間で使用寿命に至ることが明らかである。

From the results shown in Tables 4 to 6, the coated cermet tools 1 to 13 of the present invention have no chipping in the hard coating layer even in heavy cutting of various steels and cast irons accompanied by high mechanical thermal shock. The hard coating layer exhibits excellent wear resistance, whereas in the conventional coated cermet tools 1 to 13, chipping occurs in the hard coating layer, which leads to a service life in a relatively short time. It is clear.

  As described above, the coated cermet tool of the present invention has a hard coating layer not only for continuous cutting and interrupted cutting under normal conditions such as various steels and cast iron, but also for heavy cutting such as high cutting and high feed. Because it shows excellent chipping resistance and exhibits excellent cutting performance over a long period of time, it can sufficiently satisfy the high performance of cutting equipment, labor saving and energy saving of cutting work, and further cost reduction. Is.

Claims (1)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) Ti carbide layer, nitride layer, carbonitride layer, oxide, carbonate layer, and one or more layers of carbonitride oxide layer, and an overall average layer of 3 to 20 μm A Ti compound layer having a thickness;
(B) the composition _{formula: (Cr 1-X Al X} ) 2 O 3, ( provided that an atomic ratio, X: 0.30 to 0.45),
The Cr and Al vapor-deposited solid solution oxide layer satisfying the above conditions is heat-treated, and the Cr-rich Cr and Al solid solution oxide separated phase compared with Al and the Al-rich Cr and Al-rich Al and Cr A heated two-phase separated oxide layer of Cr and Al having a two-phase mixed structure composed of a solid solution oxide separated phase and having an average layer thickness of 1 to 30 μm,
A surface-coated cermet cutting tool that exhibits excellent chipping resistance in heavy cutting by forming the hard coating layer constituted by (a) and (b) by vapor deposition.