JPH07328809A - Surface covered tungsten carbide radical cemented carbide cutting tool having hard overlayer superior in interlayer adhesion performance - Google Patents

Abstract

PURPOSE:To exhibit superior cutting performance for a long time in the case of use for cutting soft steel, etc. having high cutting resistance by setting a titanium carbide nitride layer into a longitudinally oblong growth crystal structure, setting an aluminum oxide layer into mean layer thickness of a prescribed range, and setting it to 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 granular crystal structure, the second layer consisting of TiCN having similar granular crystal structure, the third layer consisting of TiC having similar granular structure, and the forth layer consisting of Al2O3 having alpha crystal structure is formed in a prescribed mean layer thickness in the range of 3-3mum. In this case, the second TiCN layer is set to a longitudinally oblong growth crystal structure and the forth Al2O3 layer is set to a structure mainly consisting of kappa crystal. A covered cemented carbide cutting tool whose interlayer adhesion performance of the hard overlayer is improved is thus provided.

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 chemical vapor deposition or physical vapor deposition, the first layer of titanium nitride (hereinafter, TiN), the second layer of titanium carbonitride (hereinafter, TiCN), titanium carbide. A third layer made of (hereinafter referred to as TiC) and a 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,
Particularly when used for cutting mild steel with high cutting resistance, interlayer adhesion of the hard coating layer is not sufficient, so delamination and chipping of the hard coating layer are likely to 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
The N layer, the second and third TiC layers, and the third layer
The interlayer adhesion between the first layer and the fourth Al ₂ O ₃ layer, and further between the fourth and fifth TiN layers, is low, which easily causes delamination and chipping. (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 TiC 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 layer has an alpha-type crystal structure. (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, and therefore, even when cutting a work material with high cutting resistance, chipping due to delamination 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. A second layer, a third layer made of TiC which also has a granular crystal structure, a fourth layer made of Al ₂ O ₃ having an alpha type crystal structure, and TiN having a granular crystal structure formed as necessary. In a coated carbide cutting tool formed by forming a hard coating layer composed of a fifth layer by a normal chemical vapor deposition method and / or physical vapor deposition method to a predetermined average layer thickness within a range of 3 to 30 μm, the TiCN layer of the second layer and longitudinal growth crystal structure, and has a the Al ₂ O ₃ layer of the fourth layer allowed improving the interlayer adhesion of the hard coating layer by a tissue mainly composed of kappa type crystal coating than Those characterized by a cutting tool.

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:} 15~35%, 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.
It is formed by sequentially depositing a TiC layer as a layer, an Al ₂ O ₃ layer as a fourth layer, and a TiN layer as a fifth layer if necessary. In some cases, the C component in the cemented carbide substrate may diffuse and form a solid solution in the TiN layer of the layer. In this case, the first layer is present as the 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 of the second TiCN layer is 3 to 20 μm, the third TiC layer is 1 to 10 μm, the fourth Al ₂ O ₃ layer is 0.1 to 15 μm, and the fifth TiN layer is 0 m. 1 ~
An average layer thickness of 5 μm is desirable.

[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 at a temperature of 1400 ° C. for 1 hour in a CH ₄ gas atmosphere of 100 torr, then subjected to a carburizing treatment by slow cooling, and after the treatment, carbon and C adhered to the surface of the base material.
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, in the cemented carbide base bodies A and D, a Co-enriched zone having a maximum Co content of 9% by weight and a depth of 20 μm was formed in the surface layer portion at a position of 15 μm from the surface as it was sintered. 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. Next, regarding the above-mentioned coated carbide cutting tools 1 to 5 of the present invention and conventional coated carbide cutting tools 1 to 5, work material: round bar of mild steel, cutting speed: 250 m / min., Feed: 0.27 mm / rev ., Depth of cut: 2 mm, Cutting time: 30 min., Continuous cutting test of mild steel, Work material: Square bar of mild steel, Cutting speed: 230 m / min., Feed: 0.27 mm / rev., Depth of cut An intermittent cutting test of mild steel was performed under the conditions of: 1.5 mm, cutting time: 40 min., And the flank wear width of the cutting edge was measured in each cutting test. 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 is a square piece of mild steel, the cutting speed is 230 m / min., The feed is 0.37 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.

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[Procedure amendment]

[Submission date] June 6, 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 carbide having the same grain structure, and a fourth layer made of aluminum oxide having an alpha crystal structure. A surface-coated tungsten carbide-based cemented carbide cutting tool comprising a hard coating layer having a predetermined average layer thickness within the range of 3 to 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 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. One layer, a second layer made of titanium carbonitride having the same granular crystal structure, a third layer made of titanium carbide having the same granular crystal structure, a fourth layer made of aluminum oxide having an alpha type crystal structure, and a granular crystal structure. A surface-coated tungsten carbide-based cemented carbide cutting tool comprising a hard coating layer composed of a fifth layer of titanium nitride having a predetermined average layer thickness within the range of 3 to 30 μm. The titanium carbonitride layer of the 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.