JPH07328808A - Surface covered tungsten car bidf rdadical cemented carbide cutting tool having hard overlater superior in interlayer a adhesion performance - Google Patents

Abstract

PURPOSE:To exhibit superior cutting performance for a long time in the case of used for cutting soft steel, etc., having high cutting resistance by setting a titanium carbide nitride layer into a longitudinally oblong growth crystal structure and setting an aluminum oxide layer into a structure mainly consisting of kappa type crystal. CONSTITUTION:On the surface of a cemented carbide base body, a hard overlayer which is formed from the first layer consisting of TiN having a granular crystal structure, the second layer consisting of TiCN having similar granular crystal structure, the third layer consisting of TiCO or TiCNO having similar granular crystal structure, and the forth layer consisting of Al2O3 having alpha crystal structure is formed in prescribed mean layer thickness in the range of 3-30mum. In this occasion, the second TiCN layer is set to a longitudinally oblong growth crystal structure and the forth Al2O3 is set to a structure mainly consisting of kappa crystal. The interlayer adhesion performance of the hard overlayer is thus improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a hard coating layer having excellent interlayer adhesion, and therefore exhibits excellent cutting performance over a long period of time when used for cutting, for example, mild steel having a large cutting resistance. The present invention relates to a surface-coated tungsten carbide based cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide cutting tool).

[0002]

2. Description of the Related Art Conventionally, as described in Japanese Patent Publication No. 57-1585 and Japanese Patent Publication No. 59-52703, for example, an entirely homogeneous tungsten carbide based cemented carbide substrate and a binder phase forming component have been used. For example, a tungsten carbide based cemented carbide substrate having a surface portion in which the content of Co or the like is relatively high compared to the inside of the substrate, that is, a surface portion having a binder phase enriched zone (hereinafter, these are collectively referred to as cemented carbide substrate. On the surface of which is formed by a chemical vapor deposition method or a physical vapor deposition method, a first layer made of titanium nitride (hereinafter referred to as TiN), a second layer made of titanium carbonitride (hereinafter referred to as TiCN), and carbonation. Third layer made of titanium (hereinafter referred to as TiCO) or titanium carbonitride oxide (hereinafter referred to as TiCNO), and fourth layer made of aluminum oxide (hereinafter referred to as Al ₂ O ₃ ).
Layer, and if necessary, a hard coating layer composed of a fifth layer made of TiN with a predetermined average layer thickness within a range of 3 to 30 μm is mainly used for alloy steel or alloy steel. It is well known that it is used for turning and milling cast iron.

[0003]

On the other hand, in recent years, FA of cutting machines has been remarkably changed, and together with the demand for labor saving in cutting, there is a tendency that cutting tools are required to have general versatility. In carbide cutting tools, there is no problem when using it for cutting alloy steel or cast iron,
In particular, when used for cutting mild steel with high cutting resistance, interlayer adhesion of the hard coating layer is insufficient, so delamination and chipping of the hard coating layer easily occur, which causes a relatively short service life. The current situation is that

[0004]

Therefore, the present inventors have
From the viewpoints described above, as a result of focusing on the above-mentioned conventional coated carbide cutting tool and conducting a study for improving the interlayer adhesion of the hard coating layer constituting the same, (a) the above conventional coated carbide In the hard coating layer constituting the cutting tool, there is no problem in the adhesion of the TiN layer of the first layer to the cemented carbide substrate, but the TiC of the first layer and the second layer
N layer, TiCO layer or TiCN of the second and third layers
The interlayer adhesion of the O layer, the Al ₂ O ₃ layers of the _third and fourth layers, and the TiN layers of the fourth and fifth layers is low, which causes delamination and chipping. Be easy. (B) In the hard coating layer constituting the above-mentioned conventional coated carbide cutting tool, a TiN layer as a first layer and a TiCN layer as a second layer
The layer, the TiCO layer or the TiCNO layer of the third layer, and the TiN layer of the fifth layer formed as necessary all have a granular crystal structure, and the Al ₂ O ₃ layer of the fourth layer has an alpha type crystal structure. To have. (C) In the hard coating layer constituting the above conventional coated carbide cutting tool, the second TiCN layer has a vertically elongated crystal structure, and the fourth Al ₂ O ₃ layer mainly has a copper crystal. Assuming that the structure has a structure (preferably, a structure in which a copper type crystal occupies 50% by volume or more, and the balance is an alpha type crystal, or a structure in which a copper type crystal is substantially formed), the resulting hard coating layer has any layer structure. Adhesion is also significantly improved, so even when cutting a work material with high cutting resistance, delamination chipping does not occur and excellent cutting performance is exhibited over a long period of time. The research results shown in (a) to (c) above were obtained.

The present invention has been made on the basis of the above-mentioned research results, and comprises a first layer of TiN having a granular crystal structure on the surface of a cemented carbide substrate, and TiCN also having a granular crystal structure. Second layer, third layer made of TiCO or TiCNO which also has a granular crystal structure
And a hard coating layer composed of a fourth layer made of Al ₂ O ₃ having an alpha-type crystal structure and a fifth layer made of TiN having a granular crystal structure, which is formed as required, by a conventional chemical method. A coated cemented carbide cutting tool formed by a vapor deposition method and / or a physical vapor deposition method to have a predetermined average layer thickness within a range of 3 to 30 μm.
Characterized by a coated carbide cutting tool in which the interlayer adhesion of the hard coating layer is improved by making the layer a vertically grown crystal structure and the fourth layer Al ₂ O ₃ layer a structure mainly composed of a kappa type crystal. I have.

The TiCN layer having the vertically elongated crystal structure of the second hard coating layer constituting the coated cemented carbide cutting tool of the present invention is, for example, as described in JP-A-6-8010. reaction gas composition: by _{volume%, TiCl 4: 1~10%,} C
_{H 3 CN: 0.1~5%, N} 2: 0~35%, H 2: remainder, reaction temperature: 850 to 950 ° C., atmospheric pressure: 30～200Torr, from forming in the conditions desired. On the other hand, a TiCN layer having a granular crystal structure usually has a reaction gas composition: volume%, TiCl ₄ : 1 to 5%, CH
_{4: 2~7%, N 2:} 15~30%, H 2: remainder, reaction temperature: 950 to 1050 ° C., atmospheric pressure: 30～200Torr, is formed by the conditions. Further, the Al ₂ O ₃ layer having a structure mainly composed of copper-type crystals is formed by reacting gas: vol.
Cl ₃ : 1 to 20%, HCl: 1 to 20% if necessary
And / or H ₂ S: 0.05 to 5%, H ₂ : remaining,
And then, _{thereafter, AlCl 3: 1~20%, CO} 2: 0.5
-30%, if necessary HCl: 1-20% and / or H ₂ S: 0.05-5%, H ₂ : remaining, reaction temperature: 850-1000 ° C., atmospheric pressure: 30-200 torr, conditions Is formed by.

In the hard coating layer constituting the coated cemented carbide cutting tool of the present invention, the TiN layer of the first layer is first deposited on the surface of the cemented carbide substrate, and then the TiCN layer of the second layer and the TiCN layer of the third layer are deposited.
Layer of TiCO layer or TiCNO layer, and fourth layer of A
It is formed by sequentially vapor-depositing a 1 ₂ O ₃ layer and, if necessary, a TiN layer of a fifth layer. When forming the second and subsequent layers, the cemented carbide is added to the TiN layer of the first layer. In some cases, the C component in the substrate may form a solid solution by diffusion, and in this case, the first layer exists as a TiCN layer after the hard coating layer is formed.

Further, the hard coating layer has an average layer thickness of 3 to
It is preferable that the average layer thickness is 3 μm.
This is because when the thickness is less than m, the desired excellent wear resistance cannot be ensured, and when the average layer thickness exceeds 30 μm, the fracture resistance rapidly decreases. Average TiN layer thickness is 0.1-5μ
m, that of the second TiCN layer is 3 to 20 μm, that of the third TiCO layer or TiCNO layer is 0.01 to 2 μm,
The Al ₂ O ₃ layer of the fourth layer is 0.1 to 15 μm, and the fifth layer
The TiN layer of the layer preferably has an average layer thickness of 0.1 to 5 μm.

[0009]

EXAMPLES Next, the coated cemented carbide cutting tool of the present invention will be specifically described by way of examples. As the raw material powder, a medium-grain WC powder having an average particle diameter of 3 μm and a coarse-grain WC having the same particle diameter of 5 μm
Powder, 1.5 μm (Ti, W) C (weight ratio, same below, TiC / WC = 30/70) powder, 1.2 μm
(Ti, W) CN (TiC / TiN / WC = 24/2
0/56) powder, 1.3 μm of (Ta, Nb) C (T
aC / NbC = 90/10) powder, and the same 1.2 μm
Co powder of No. 1 was prepared, these raw material powders were compounded to the compounding composition shown in Table 1, and wet-mixed for 72 hours with a ball mill,
After being dried, it is press-molded into a green compact having a shape defined by ISO / CNMG120408 (for cemented carbide base bodies A to D) and SEEN42AFTN1 (for cemented carbide base body E),
Cemented carbide base bodies A to E were manufactured by vacuum-sintering the green compact under the conditions shown in Table 1. Further, the cemented carbide base material B was held in a CH ₄ gas atmosphere of 100 torr at a temperature of 1400 ° C. for 1 hour and then subjected to a slow carburizing treatment.
By removing o by acid and barrel polishing, a Co-enriched zone having a maximum Co content of 15% by weight and a depth of 40 μm was formed in the surface layer of the substrate at a position of 10 μm from the surface.
Further, on the cemented carbide base bodies A and D, as-sintered, a Co-enriched zone having a maximum Co content of 9 wt% and a depth of 20 μm was formed on the surface layer portion at a position of 15 μm from the surface. And the remaining Cemented Carbide Substrates C and E contain the above C
o There was no formation of enriched zones, and there was an overall homogeneous structure. Further, Table 1 shows the above cemented carbide substrates AE.
The internal hardness (Rockwell hardness A scale) of each is shown.

Then, the surfaces of these cemented carbide substrates A to E were subjected to honing, using a conventional chemical vapor deposition apparatus, under the conditions shown in Table 2 under the conditions shown in Table 2 and the compositions shown in Tables 3 to 6 The coated carbide cutting tools 1 to 7 of the present invention and the coated carbide cutting tools 1 to 7 of the related art were manufactured by forming a crystal structure and a hard coating layer having an average layer thickness. In addition,
FIG. 1 shows a structure photograph (5000 times) of the coated carbide cutting tool 1 of the present invention by a metallurgical microscope. Next, the above-mentioned coated carbide cutting tools 1 to 5 of the present invention and the conventional coated carbide cutting tool 1
About 5, the work material: round bar of mild steel, cutting speed: 280 m / min., Feed: 0.23 mm / rev., Depth of cut: 2 mm, cutting time: 30 min., Continuous cutting test of mild steel, And the work material: mild steel square bar, cutting speed: 260 m / min., Feed: 0.23 mm / rev., Depth of cut: 1.5 mm, cutting time: 40 min. In each of the cutting tests, the flank wear width of the cutting edge was measured. The results of these measurements are shown in Tables 4 and 6. Further, regarding the above-mentioned coated carbide cutting tools 6 and 7 of the present invention and conventional coated carbide cutting tools 6 and 7, the work material: square bar of mild steel, cutting speed: 260 m / min., Feed: 0.33 mm / blade, Milling of mild steel was performed under the following conditions: depth of cut: 2.5 mm, cutting time: 40 min, and the flank wear width of the cutting edge was measured. The measurement results are also shown in Tables 4 and 6.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

[Table 4]

[0015]

[Table 5]

[0016]

[Table 6]

[0017]

From the results shown in Tables 3 to 6, the coated carbide cutting tools 1 to 7 of the present invention are not susceptible to delamination or chipping of the hard coating layer despite the cutting of mild steel having high cutting resistance. While it does not occur and shows excellent wear resistance,
Since the conventional coated carbide cutting tools 1 to 7 have insufficient interlayer adhesion in the hard coating layer, delamination and chipping occur in the cutting of mild steel, and it is clear that they reach the service life in a relatively short time. is there. As described above, the coated cemented carbide cutting tool of the present invention has excellent interlayer adhesion of the hard coating layer forming the same, so that not only cutting of alloy steel or cast iron, but also of mild steel having high cutting resistance, etc. Even when it is used for cutting, it exhibits excellent cutting performance for a long period of time.

[Brief description of drawings]

FIG. 1 is a microstructure photograph (5000 times) of a surface portion of a coated carbide cutting tool 1 of the present invention, taken by a metallurgical microscope.

[Procedure amendment]

[Submission date] July 5, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

[Table 1]

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Claims (2)

[Claims] 1. A titanium carbide-based cemented carbide substrate that is wholly homogeneous, or a titanium carbide-based cemented carbide substrate that has a binder phase enriched zone in the surface layer and is made of titanium nitride having a granular crystal structure. One layer, a second layer made of titanium carbonitride having the same grain structure, a third layer made of titanium carbonate or titanium oxycarbonitride having the same grain structure, and a third layer made of aluminum oxide having an alpha type crystal structure. 3 to 4 hard coating layers composed of 4 layers
A surface-coated tungsten carbide-based cemented carbide cutting tool formed to have a predetermined average layer thickness within a range of 30 μm, wherein the second titanium carbonitride layer has a vertically elongated crystal structure,
A surface-coated tungsten carbide-based cemented carbide cutting tool having excellent interlayer adhesion with a hard coating layer, characterized in that the fourth aluminum oxide layer has a structure mainly composed of copper crystals. 2. A tungsten carbide-based cemented carbide substrate which is wholly homogeneous, or a titanium carbide-based cemented carbide substrate which has a binder phase-enriched zone in the surface layer, and which comprises titanium nitride having a granular crystal structure. One layer, a second layer made of titanium carbonitride also having a granular crystal structure, a third layer made of titanium carbonate or titanium carbonitride oxide also having a granular crystal structure, a fourth layer made of aluminum oxide having an alpha type crystal structure. A hard coating layer composed of a layer and a fifth layer made of titanium nitride having a granular crystal structure.
A surface-coated tungsten carbide-based cemented carbide cutting tool formed with a predetermined average layer thickness within a range of μm, wherein the second titanium carbonitride layer has a vertically elongated crystal structure,
A surface-coated tungsten carbide-based cemented carbide cutting tool having excellent interlayer adhesion with a hard coating layer, characterized in that the fourth aluminum oxide layer has a structure mainly composed of copper crystals.