JPS63274771A - Surface-treated cemented carbide alloy member - Google Patents

Abstract

PURPOSE:To obtain a surface-treated cemented carbide alloy member free from peeling of coating layer and excellent in machinability, by successively forming an intermediate softened layer, a surface semihard layer, and a coating layer each having a specific composition on the surface of a base material for a cemented carbide alloy with a specific composition to respectively specified layer thicknesses. CONSTITUTION:A base material of cemented carbide alloy has a composition consisting of, by volume, 5-30% Co and the balance WC and further containing, if necessary, 5-30% of NaCl-type crystalline structure of the carbides (excluding WC), nitrides, and carbonitrides of the group-IVa, -Va, and -VIs metals of the periodic table. On the surface of the above, an intermediate softened layer which has a composition consisting of 15-30% Co and the balance WC and further containing, if necessary, 5-30% of the same NaCl-type crystalline structure as mentioned above is formed to 2-50mum layer thickness. On the surface of the above layer, a surface semihard layer consisting of 3-15% Co and the balance WC and further containing, if necessary, 5-30% of the same NaCl-type crystalline structure as mentioned above is formed to 0.1-30mum layer thickness. Further, a single or multiple coating layer consisting of the same carbides, etc., as mentioned above and Al2O3 is formed to 1-20mum layer thickness on the above-mentioned layer. Moreover, by constituting the above-mentioned layers of structures having respectively proper hardnesses, the surface-treated cemented carbide alloy member can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention has excellent wear resistance and plastic deformation resistance, is rich in toughness, has a strong adhesion of the coating layer, and has excellent machinability. The present invention relates to a surface-coated cemented carbide member showing the following.

[Conventional technology]

Conventionally, for example, 4a, 5a, and 6 of the periodic table are coated on the surface of a tungsten carbide (hereinafter referred to as we)-based cemented carbide substrate.
Group A metal carbides (excluding WC), nitrides, carbonitrides, carbonates, and carbonitrides, aluminum oxide, and solid solutions of two or more of these. A surface-coated cemented carbide member having a coating layer or a multilayer of two or more layers is known, and in order to further improve the toughness of this known surface-coated cemented carbide member, it is necessary to Surface [By modifying the cemented carbide base by providing an intermediate soft layer made of WC-Go and a hard surface layer made of NaCl-type crystal structure -Co on top of it, and then forming the final coating layer, A method of improving the adhesion of the coating layer has been attempted (Japanese Unexamined Patent Publication No. 55-134107), and has shown excellent results.

[Problem that the invention seeks to solve]

However, although the coated tool material obtained by the method described in JP-A-55-134107 exhibits good properties in continuous cutting, there is a problem in that the coating layer peels off in interrupted cutting.

[Means for solving problems]

Therefore, the present inventors solved the problems of the conventional surface-coated cemented carbide members, and achieved excellent plastic deformation resistance and toughness even during interrupted cutting, and high adhesion of the coating layer to prevent peeling. This is the result of research into surface-coated cemented carbide parts that prevent this from occurring.

Between the surface of the cemented carbide base and the coating layer, an intermediate softened layer is formed in which the interior of the cemented carbide base is soft and has high toughness, and a semi-hard surface layer is formed in which the interior of the cemented carbide base is also hard. Ba,
Good followability to deformation between the coating layer and the cemented carbide substrate suppresses the occurrence of peeling, further suppresses the propagation of cracks from the coating layer to the coating layer, significantly improves toughness, and facilitates interrupted cutting. They obtained the knowledge that good characteristics can be obtained for.

This invention was made based on this knowledge, and includes an intermediate softening layer with a layer thickness of 2 to 50 μm formed on the surface of a cemented carbide base, and a layer thickness of 0 μm formed on the intermediate softening layer. .1
A surface-coated cemented carbide member consisting of a semi-hard surface layer of ~30 μm and a coating layer of 21 to 20 μm in thickness formed on the semi-hard surface layer, the interior of the cemented carbide base being Co: 5 to 3o capacity CH (hereinafter, CH regarding component composition is volume %), WC: composition consisting of the remainder, or carbides of metals of groups 4a, 5a and 6a of the periodic table (excluding WC), NaCt type crystal structure consisting of one or more types of nitride and carbonitride = 5 to 30%, Co:
The intermediate softening layer has a composition consisting of Co: 15 to 30% and WC: the balance, or a composition of metals from groups 4a, 5a and 6a of the periodic table. carbide(
(excluding WC), NaCt type crystal structure consisting of one or more types of nitrides and carbonitrides: 5 to 30
%, Co: l 5-30%.

WC: The surface semi-hard layer is composed of the remainder.

Composition consisting of Co2 3-15%, WC: balance, or 2
NaCt-type crystal structure consisting of one or more types of carbides (excluding WC), nitrides, and carbonitrides of metals in groups 4a, 5a, and 6a of the periodic table: 5 to 30%
, Co: 3 to 15%, and WC: the balance.

, carbides of metals of groups 4a, 5a and 6a of the periodic table (
(excluding wC), nitrides and carbonitrides.

One of the group consisting of solid solutions of two or more of carbonates, carbonate nitrides, aluminum oxide, and K.
The surface ratio hardened layer is 5 to 125% harder in terms of Vickers hardness than the intermediate softened layer, and the intermediate softened layer is , Vickers hardness is 20 to 6 compared to the inside of the cemented carbide base.
This is characterized by a surface-coated cemented carbide member having a zero-softened structure.

Next, the reasons for limiting the composition and hardness of the coating layer, semi-hard surface layer, intermediate softening layer, and cemented carbide base in the surface-coated cemented carbide member of the present invention will be described. Since the internal composition is well known, it will not be described in detail, but the composition and hardness of the surface semi-hard layer and the intermediate soft layer will be described in detail.

(a) Surface semi-hard layer Peeling of the coating layer largely depends on the degree of mismatch in toughness between the coating layer and the cemented carbide substrate against plastic deformation during cutting. Therefore, in this invention, a semi-hard surface layer harder than the intermediate softening layer is formed between the coating layer and the intermediate softening layer to alleviate the difference in hardness between the coating layer and the intermediate softening layer. The aim is to compensate for the lack of strength in the steel, improve the ability to follow deformation, and improve the adhesion of the coating layer.

The composition of this surface semi-hard layer is Co: 3 to 15%, WC:
The remainder, or Co: 3-15%, 4a, 5 of the periodic table
NaCl-type crystal structure (hereinafter simply referred to as NaCl-type compound) consisting of one or more types of carbides (excluding WC), nitrides, and carbonitrides of metals of group a and 6a groups (hereinafter simply referred to as NaCl-type compounds)': 5 to 30 %, WC: composed of any of the remaining parts
, Co: If the content is less than 3%, the desired toughness cannot be obtained, and if the content exceeds 15%, the desired hardness cannot be obtained, leading to insufficient wear resistance. Regarding the NaCL type compound, if it is less than 5%, the wear resistance is insufficient, and if it exceeds 30%, the toughness is insufficient.

Regarding the particle size of WC and NaCl type compounds.

Generally, it is preferable that the particle size be slightly smaller than that of the WC and NaCl type compounds in the intermediate softening layer.

The hardness of the surface semi-hard layer needs to be 5 to 125% harder in terms of hardness than the hardness of the intermediate softening layer; if it is less than 5%, the desired improvement effect cannot be obtained, while if it exceeds 125%, it is hard. When this happens, the toughness decreases significantly.

In addition, if the thickness of the surface semi-hard layer is less than 0.1 μm, the desired improvement effect will not be obtained, and if it exceeds 30 μm, the toughness will decrease.
It was set as m.

(b) Liquid level on the surface of the intermediate softened layer It is thought that fractures in cemented carbide tools are usually caused by crack propagation from the coating layer into the interior of the cemented carbide base. Between the semi-hard layer and the surface of the cemented carbide substrate, the layer thickness is 2 to 50 μm, and the hardness of the inside of the cemented carbide substrate is 20 to 60%.
By forming a softened layer rich in toughness,
The aim was to suppress the propagation of cracks from the hard coating layer and to improve strength and toughness. The hardness of the intermediate softened layer is 2 Vickers hardness compared to the inside of the cemented carbide base.
If the softening is less than 0%, the desired toughness improvement effect cannot be ensured, while if the softening exceeds 60%, the plastic deformation resistance and peeling resistance of the coating are significantly reduced.
The hardness of the intermediate softened layer is set to be 20 to 60 degrees softer in terms of Vickers hardness than the internal hardness of the base.

Furthermore, if the layer thickness is less than 2 μm, the desired toughness improvement effect cannot be obtained, whereas if the layer thickness exceeds 50 μm,
Since this results in a significant decrease in plastic deformation resistance, the thickness of the intermediate softened layer was set at 2 to 50 μm.

The intermediate softening layer is composed of Co: 15-30%, WC: balance, or Co: 15-30%, Na C type compound: 5-3
0%, WC: the balance, and the reason for this limitation is the same as that described in the surface hard layer. However, W
The particle sizes of C and NaCt type compounds are.

It is preferable that the particle size of the WC and NaCl type compounds in the semi-hard surface layer be slightly coarser.

Regarding the thickness of the coating layer, if the layer thickness is less than 1 μm, the desired effect of improving wear resistance cannot be secured;
If the layer thickness exceeds 1 m, the toughness will decrease significantly.
It was determined to be ~20 μm. This coating layer can be formed by conventional coating layer forming methods such as chemical vapor deposition, ion blasting, and sputtering.

〔Example〕

Next, the present invention will be specifically explained based on examples.

Commercially available raw material powders were blended so as to have the final component composition shown in Table 1 as the internal composition of the cemented carbide base, and mixed for 48 hours in a ball mill.

Form a green compact by drying and pressing.

Next, N
After uniformly spraying in a N2 gas atmosphere and drying under reduced pressure, the mixed powder mixture slurry shown in Table 1 for forming a semi-hard layer on the surface was similarly sprayed to a predetermined thickness in a N2 gas atmosphere. Spray uniformly at , dry under reduced pressure and then at temperature:
By holding and sintering at 1400°C for 1 hour, a SNU 432 type indexable chip with a semi-hard surface layer and an intermediate softening layer was manufactured, and the layer thickness and Vickers hardness of the semi-hard surface layer and the intermediate softening layer were determined. The results are shown in Table 1.

On the surface of the above SNU 432 type throwaway tip,
It was prehoned to 0.0513+, charged into a chemical vapor processing furnace, and heated to 4% TiCL4 under atmospheric pressure.
While introducing a gas consisting of 4% tCH4 and 92% (volume %) N2, the temperature was kept at 1050°C for 5 hours to coat TiCfffl with a thickness of 5 μm, followed by 2% AlCl3, While introducing a gas consisting of Co□:6 and N2:9296 (volume %), a temperature of 1000°C was maintained for 2 hours to coat a 'yt2o3 layer with a layer thickness of 1 μm, resulting in a total coating layer of 6 μm. A throw-away tip of the present invention was manufactured.

Regarding the above indexable insert of the present invention, (1) Work material: SN0M439 (HB: 320) Cutting speed:
150 m/mJL Feed: 0.6 NL/rev.

Continuous cutting tests were conducted under conditions of depth of cut: 3B, and flank wear and crater wear were measured.

(2) Work material: SN0M439 (HB: 270) Grooved round bar Cutting speed: 120m/Ugly feed: 0.4 pieces/rev.

An interrupted cutting test was conducted at a depth of cut of 23M, and the time until the cutting edge broke was measured.

The results of the cutting tests in (1) and [2) above are also shown in Table 1.

Next, as a conventional example, the above-mentioned Japanese Patent Application Laid-Open No. 55-134107
A cutting test was conducted under the same conditions as (1) and (2) above using the conventional throw-away tip shown in the above publication and having a hardened surface layer that does not contain WC. The results are also shown in Table 2.

〔Effect of the invention〕

Comparing the results of cutting tests using the indexable insert of the present invention (Table 1) and the results of cutting tests using the conventional indexable insert (Table 2),
Although both have almost the same effect in continuous cutting tests, it is clear that the indexable insert of the present invention is far superior to interrupted cutting tests.

Therefore, even if the present invention is used as a cutting tool to cut a workpiece that has an uneven surface, the chipping time is longer than that of conventional cutting tools, and it is effective against interrupted cutting. be.

Claims (1)

[Claims] An intermediate softened layer formed on the surface of the cemented carbide substrate with a layer thickness of 2 to 50 μm, and a layer thickness formed on the intermediate softened layer of 0.1 μm.
A surface coated cemented carbide member consisting of a semi-hard surface layer of ~30 μm and a coating layer formed on the semi-hard surface layer with a thickness of 1 to 20 μm, the interior of the cemented carbide base being A composition consisting of Co: 5 to 30%, WC: the balance, or one or two of carbides (excluding WC), nitrides, and carbonitrides of metals in groups 4a, 5a, and 6a of the periodic table. NaCl type crystal structure consisting of the above: 5 to 30%
, Co: 5-30%, WC: balance, the intermediate softening layer has a composition consisting of Co: 15-30%, WC: balance, or a composition of groups 4a, 5a and 6a of the periodic table. NaCl-type crystal structure consisting of one or more of metal carbides (excluding WC), nitrides, and carbonitrides: 5 to 30%
, Co: 15-30%, WC: balance, the surface semi-hard layer has a composition consisting of Co: 3-15%, WC: balance, or Groups 4a, 5a and 6a of the periodic table. NaCl-type crystal structure consisting of one or more of metal carbides (excluding WC), nitrides, and carbonitrides: 5 to 30%
, Co: 3 to 15%, and WC: the balance, and the coating layer includes carbides (excluding WC), nitrides, and carbonitrides of metals in groups 4a, 5a, and 6a of the periodic table. , carbonate, carbonate nitride, aluminum oxide, and a composition consisting of a single layer or a multilayer of two or more of the solid solutions of two or more of these (%
is % by volume), the hardness of the semi-hardened surface layer is 5 to 125% harder in Vickers hardness than the hardness of the intermediate softened layer, and the intermediate softened layer has a Vickers hardness of 5 to 125% harder than the hardness of the intermediate softened layer, and A surface-coated cemented carbide member characterized by having a structure whose hardness is softened by 20 to 60%.