JP2019042830A - Composite sintered cutting tool - Google Patents

Abstract

A composite sintered cutting tool made of a TiCN-based cermet and a WC-based cemented carbide, which reduces the amount of tungsten used and has excellent resistance to peeling and thermal cracking. A composite sintered body cutting tool of a TiCN-based cermet and a WC-based cemented carbide, wherein at least a part of the outer peripheral surface including the cutting edge is a WC-based cemented carbide layer (preferably, a composite sintered body). 0.03 to 0.3 times the thickness of the solid cutting tool), and the average layer thickness is from the interface between the WC-based cemented carbide layer and the TiCN-based cermet to the WC-based cemented carbide layer side An interfacial layer of 5 to 200 μm is formed, and the interfacial layer is composed of WC particles occupying 5 to 50 area % and a mixed phase occupying 50 to 95 area %. The total content is 0.8 to 1.2 times the total content of Co and Ni present in the mixed phase (atomic ratio), and the TiCN-based cermet contains one or more layers of TiCN A composite sintered cutting tool comprising a base cermet layer. [Selection diagram] Fig. 1

Description

  The present invention relates to a cutting tool composed of a composite sintered body of a TiCN-based cermet and a WC-based cemented carbide, and in particular, it is intended to reduce the amount of tungsten used as a rare metal while reducing the amount of tungsten used to perform composite sintering. Generation of peeling of WC base cemented carbide layer and heat in wet interrupted cutting where thermal and mechanical high load act on the cutting edge even when the layer thickness of WC base cemented carbide layer in the body is reduced The present invention relates to a composite sintered body cutting tool capable of suppressing the occurrence of a crack and exhibiting excellent cutting performance over long-term use.

  WC-based cemented carbide is widely used as a cutting tool for steel and cast iron, but various proposals have been made to reduce the amount of tungsten, which is a rare metal, and obtain desired cutting performance. It is done.

  For example, in Patent Document 1, a cemented carbide layer and a cermet layer containing WC and W in total of 15 to 65 mass% or less in total and 80 mass% or more of iron group metals in the binder phase are Co are laminated. In the cutting tool made of a base material, the base material has a maximum thickness h1 in the stacking direction and a maximum thickness h2 in the stacking direction of the cemented carbide layer of the cutting edge portion, h2 / h1 is 0.002 to 2. By setting it as 0.02, the composite sintered compact cutting tool which improved impact resistance and surface glossiness is proposed.

Further, for example, in Patent Document 2, in the case of a composite sintered body cutting tool comprising a composite sintered body of a TiCN-based cermet and a WC-based cemented carbide, the rake surface including the cutting edge of the cutting tool comprises an iron group metal component Of 4 to 17% by mass, the balance being WC base cemented carbide containing WC as the main hard phase component, and the thickness of the WC base cemented carbide is 0.05 to 0. 5 of the thickness of the composite sintered body. The TiCN-based cermet, which is three times as large as the mother body of the cutting tool, has 4 to 25 mass% of the iron group metal component and 15 mass% of W when the content ratio of constituent components of the cermet is expressed by the content ratio of the metal component Less than, 2 to 15 mass% of Mo, 2 to 10 mass% of Nb, 0.2 to 2 mass% of Cr, and total content of Co and Ni for Co and Ni which are iron group metal components The content ratio of Co to the amount satisfies 0.5 to 0.8 (mass ratio). Composite sintered body cutting tool in so that there has been proposed.
And, according to this cutting tool, while being able to aim at reduction of the amount of use of tungsten which is a rare metal, when it uses for intermittent cutting which an intermittent high impact acts on a cutting edge, propagation of a crack ・It is said that it can improve the progress suppressing action and suppress the occurrence of abnormal damage such as chipping, chipping and peeling.

Patent No. 5185032 JP, 2016-68156, A

  In the composite sintered body cutting tool shown in the above-mentioned Patent Document 1, since W and WC of 15% by mass or more are required in the cermet, the reduction of the amount of tungsten used is insufficient and such a reduction When the cutting tool is used for wet intermittent cutting, not only strength and toughness are insufficient but also peeling resistance and heat cracking resistance are not sufficient, so there is a problem that abnormal damage such as chipping and breakage is easily broken. there were.

In addition, in the composite sintered body cutting tool composed of WC-based cemented carbide and TiCN-based cermet shown in Patent Document 2 described above, the amount of tungsten used can be reduced to a certain extent, but the layer of WC-based cemented carbide layer When the thickness is reduced, stress concentration is generated at the interface between the WC-based cemented carbide layer and the TiCN-based cermet based on the difference in the thermal expansion coefficient, and interface peeling is likely to occur. In such a case, abnormal damage such as chipping, chipping or peeling due to the occurrence of interfacial peeling or the like may occur.
Therefore, it can not be said that the reliability in the cutting process in which a high thermal and mechanical high load acts by the cutting edge is satisfactory.

  Therefore, in the present invention, in the case of using a sintered compact of a TiCN based cermet and a WC based cemented carbide composite, while reducing the use amount of tungsten, which is a rare metal, and thinning the WC based cemented carbide layer. Even if the WC base cemented carbide layer can be suppressed from peeling, and even when used in wet interrupted cutting where a high thermal and mechanical load acts on the cutting edge, peeling and thermal cracking It is an object of the present invention to provide a composite sintered body cutting tool excellent in resistance to abnormal damage such as chipping, chipping and peeling, by suppressing the occurrence of

  The inventors of the present invention have attempted to reduce the amount of tungsten used in a composite sintered body cutting tool made of a composite sintered body of a TiCN based cermet and a WC based cemented carbide from the above viewpoint, and to use a WC based cemented carbide layer. The following findings were obtained as a result of intensive investigation on a cutting tool capable of suppressing the occurrence of peeling at the interface between the above and TiCN-based cermet.

  The present inventors specified a composite sintered body in a specific temperature range at the time of cooling of a sintering process when producing a composite sintered body by sintering a WC base cemented carbide and a TiCN base cermet. If a specific interface layer is formed on the WC-based cemented carbide layer side of the interface between the WC-based cemented carbide layer and the TiCN-based cermet by adding a heat treatment step of holding for a certain time, the presence of this interface layer And the peeling strength at the interface between the WC-based cemented carbide layer and the TiCN-based cermet even if the layer thickness of the WC-based cemented carbide layer is decreased because the bonding strength between the WC-based cemented carbide layer and the TiCN-based cermet is enhanced. First of all, I found that I could suppress the occurrence.

In addition, when sintering WC base cemented carbide and TiCN base cermet, at the interface of contact between WC base cemented carbide layer and TiCN base cermet, when sintering WC base cemented carbide and TiCN base cermet The stress concentration occurs due to the difference in thermal expansion coefficient, which is one of the causes of peeling of the WC-based cemented carbide layer. The present inventors, as a TiCN-based cermet, adjust the thermal expansion coefficient by adjusting the component composition. By using a TiCN-based cermet composed of two or more layers different from each other and arranging the TiCN-based cermet close to the thermal expansion coefficient of the WC-based cemented carbide as the TiCN-based cermet adjacent to the WC-based cemented carbide layer Since it is possible to apply a larger compressive stress to the thinned WC base cemented carbide layer through the interface layer having high bonding strength formed on the WC base cemented carbide layer, Beyond basic In addition to the peeling inhibition effect of the alloy layer it is was found that it is possible to also suppress the generation of heat cracking caused by thermal high load.

  That is, in the cutting tool made of the composite sintered body, the use amount of tungsten which is a rare metal is reduced by the presence of the interface layer having high bonding strength, and the layer thickness of the WC base cemented carbide layer is reduced. In addition to being able to prevent the occurrence of peeling at the interface between the WC-based cemented carbide layer and the TiCN-based cermet even when the WC-based cemented carbide layer is thinned, By adjusting the component composition of the adjacent TiCN-based cermet, the WC-based cemented carbide layer can provide a larger compressive stress, so intermittent high-impact mechanical high load and heating on the cutting edge Even in wet interrupted cutting of alloy steel or the like where high thermal load acts by the thermal cycle of cooling, long-term use can be achieved without causing abnormal damage caused by peeling, thermal cracking, etc. It was found to exert a cutting performance of gray.

The present invention has been made based on the above findings, and
“(1) In a composite sintered body cutting tool comprising a composite sintered body of a TiCN based cermet and a WC based cemented carbide,
(A) At least a part of the surface of the outer peripheral portion including the cutting edge of the composite sintered body cutting tool is composed of a WC-based cemented carbide layer,
(B) An interface layer having an average layer thickness of 5 to 200 μm is formed on the WC-based cemented carbide layer side from the interface between the WC-based cemented carbide layer and the TiCN-based cermet,
(C) The interface layer is composed of WC particles occupying 5 to 50 area% and a mixed phase occupying 50 to 95 area%,
(D) The total content of W and Mo present in the mixed phase is 0.8 to 1.2 times (in atomic ratio) the total content of Co and Ni present in the mixed phase Composite sintered body cutting tool characterized in that.
(2) WC containing at least 4 to 17% by mass of an iron group metal component as a binder phase component and at least WC as a hard phase component at least a part of the rake face including the cutting edge of the composite sintered body cutting tool The composite sintered body cutting tool according to (1), which is composed of a base cemented carbide layer.
(3) The thickness of the WC-based cemented carbide layer is 0.03 to 0.3 times the thickness of the composite sintered body cutting tool according to (1) or (2). Composite sintered cutting tools.
(4) The TiCN-based cermet is composed of two or more layers of TiCN-based cermet layers, and the TiCN-based cermet layer adjacent to the interface layer of the WC-based cemented carbide layer contains the content ratio of the component of the cermet When expressed by the content ratio of the components, at least 4 to 25 mass% of the iron group metal component, less than 15 mass% of W, 2 to 15 mass% of Mo, 2 to 10 mass% of Nb, and 0.2 to Cr That the Co content is 0.5 to 0.8 times (with an atomic ratio) relative to the total content of Co and Ni, which contains 2% by mass, and Co and Ni which are iron group metal components The composite sintered body cutting tool according to any one of (1) to (3), characterized in that
(5) A hard coating layer is formed on the surface of the WC-based cemented carbide layer including at least the cutting edge of the composite sintered body cutting tool according to any one of the above (1) to (4) The composite sintered body cutting tool according to claim 1. "
It is characterized by

  Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic longitudinal sectional view of a composite sintered body cutting tool according to the present invention, wherein (a) shows an example of the composite sintered body cutting tool according to the present invention, and (b) shows The other example of the composite sintered compact cutting tool of this invention in which the TiCN base cermet is comprised by multiple layers (two layers) is shown.
FIG. 2 shows a schematic vertical cross-sectional schematic view of a composite sintered body cutting tool according to the present invention in which a hard coating layer is provided on the surface of a WC-based cemented carbide layer, and FIG. In the composite sintered body cutting tool shown, a composite sintered body cutting tool in which a hard coating layer is provided on the surface of the WC base cemented carbide layer is shown, and (b) shows the composite sintering shown in FIG. 1 (b) The body sintered cutting tool WHEREIN: The composite sintered compact cutting tool by which the hard coating layer was provided in the surface of the WC base cemented carbide layer is shown.
Fig.3 (a) shows an example of the longitudinal cross-section SEM image of the compound sintered compact cutting tool of this invention, (b) shows the elements on larger scale.

In the composite sintered body cutting tool of the present invention, as shown in FIG. 1 and FIG. 2, the entire cutting tool is not made of WC base cemented carbide, but TiCN base cermet as a base and outer periphery including cutting edge The WC-based cemented carbide layer is provided on at least a part of the surface, for example, the rake surface.
Also, as shown in FIGS. 2 (a) and 2 (b), in the present invention, for example, the surface of the WC-based cemented carbide layer provided on the rake face of the cutting tool is hard by physical vapor deposition, chemical vapor deposition or the like. By forming a coating layer by vapor deposition, a composite sintered body cutting tool provided with a hard coating layer on the surface can also be obtained.

The composite sintered body cutting tool of the present invention can be manufactured by the following manufacturing method.
First, a TiCN-based cermet powder having a predetermined composition and a WC-based cemented carbide powder having a predetermined composition are prepared, and these powders are pressed to form a composite molded body in which the TiCN-based cermet and the WC-based cemented carbide are laminated. Is then sintered at a sintering temperature of 1400 ° C. to 1440 ° C. for 1 hour to 1.5 hours, for example, in a nitrogen atmosphere of 0.1 kPa.
Next, in a cooling process after sintering, a heat treatment is performed to maintain the temperature range of 1330 ° C. to 1370 ° C. for 0.8 hr to 1.5 hr, and then the composite sintered body is manufactured by cooling to room temperature.
By performing such sintering, an interface layer, which will be described later, is formed at the interface between the WC base cemented carbide layer and the TiCN base cermet and from the interface to the WC base cemented carbide layer side.
Subsequently, the composite sintered body cutting tool of the present invention can be manufactured by processing the obtained composite sintered body into a predetermined shape.
Further, in the preparation of the composite molded body, heat is adjusted by adjusting the component composition as a TiCN-based cermet composed of two or more TiCN-based cermet layers and as a TiCN-based cermet adjacent to the WC-based cemented carbide layer. By placing and sintering a TiCN-based cermet whose expansion coefficient is close to that of WC-based cemented carbide, the WC-based cemented carbide layer is formed on the WC-based cemented carbide layer side via the interface layer with high bonding strength. The composite sintered body cutting tool of the present invention in which a large compressive stress is applied to the cemented carbide layer can be manufactured.
Furthermore, on the surface of the WC-based cemented carbide layer of the composite sintered body cutting tool of the present invention prepared above, a Ti compound layer, a composite nitride layer of Ti and Al, Al by physical vapor deposition, chemical vapor deposition, etc. The composite sintered body according to the present invention has a hard coating layer formed on the surface of a WC-based cemented carbide layer by vapor deposition of a hard coating layer such as a ₂ O ₃ layer as a single layer or a multi-layered film. Tools can be manufactured.

Interfacial layer formed at the interface of WC-based cemented carbide layer and TiCN-based cermet:
In the production of the composite sintered body cutting tool of the present invention, as described above, the composite compact is sintered in the sintering step at a sintering temperature of 1400 ° C. to 1440 ° C. for 1 hour to 1.5 hours and then cooled The interface layer, which is one of the features of the present invention, is heat treated at a temperature range of 1330.degree. C. to 1370.degree. C. for 0.8 to 1.5 hours to form an interface between WC base cemented carbide and TiCN base cermet. The WC-based cemented carbide layer side is formed with an average layer thickness of 5 to 200 μm.
Then, by forming this interface layer, the bonding strength between the WC-based cemented carbide layer and the TiCN-based cermet can be increased, so that the amount of tungsten, which is a rare metal, is reduced, and the WC-based cemented carbide layer is formed. Even when the layer thickness is reduced, WC-based cemented carbide layers are used in wet interrupted cutting such as alloy steel where intermittent high-impact mechanical high load and high thermal load act on the cutting edge. The occurrence of peeling at the interface of the TiCN-based cermet is suppressed.

In addition, in producing the composite sintered body cutting tool, the TiCN-based cermet is composed of two or more TiCN-based cermet layers, and as the TiCN-based cermet adjacent to the WC-based cemented carbide layer, WC-based cemented carbide In the composite sintered body cutting tool of the present invention in which a TiCN-based cermet having a thermal expansion coefficient close to that of the present invention is placed and sintered, the formation of the interface layer ensures a high bonding strength, so the layer of WC-based cemented carbide layer Even when the thickness is reduced, it is possible to apply a large compressive stress to the WC-based cemented carbide layer.
As a result, even when subjected to wet intermittent cutting of alloy steel or the like where intermittent high-impact mechanical high load and thermal high load act on the cutting edge, the WC-based The occurrence of peeling at the interface between the hard metal layer and the TiCN-based cermet is suppressed, and the large compressive stress of the WC-based cemented carbide layer also prevents the generation of thermal cracks due to the thermal cycle of heating and cooling. Excellent cutting performance is exhibited over long-term use without causing any abnormal damage caused by the generation or thermal cracking.

  The interface layer formed in the composite sintered body cutting tool is composed of WC particles occupying 5 to 50 area% and a mixed phase occupying 50 to 95 area% when the longitudinal cross section is observed. When the area ratio of WC particles is less than 5 area% or when the area ratio of mixed phase exceeds 95 area%, the hardness of the interface layer becomes significantly lower than that of the WC base cemented carbide layer and the TiCN base cermet, As a result, the interface layer is highly likely to be deformed or broken during cutting, while the interface ratio of the WC particles exceeds 50 area%, or the interface ratio of the mixed phase is less than 50 area%. Since the thermal expansion coefficient of the layer is close to that of WC base cemented carbide, stress concentration occurs at the interface with the TiCN base cermet, and breakage easily occurs, so the area ratio of WC particles constituting the interface layer is 5 to 50 area The area ratio of a mixed phase is 50 to 95 area%.

Further, the mixed phase contains at least W, Mo, Co and Ni as component elements constituting the phase, but the total amount of W and Mo present in the mixed phase is present in the mixed phase The total amount of Co and Ni is 0.8 to 1.2 times, that is, 0.8 ≦ (W + Mo) / (Co + Ni) ≦ 1.2 in atomic ratio.
This is because if the value of (W + Mo) / (Co + Ni) is less than 0.8, a graphite phase appears as a heterophase in the interface layer and the interface layer becomes largely embrittled, while (W + Mo) / (Co + Ni) When the value of the value of 1.2 exceeds 1.2, the binder phase component is easily moved from the TiCN-based cermet to the interface layer, and as a result, a void is generated in the TiCN-based cermet and the fracture tends to occur.

Furthermore, the interface layer formed on the WC-based cemented carbide layer side from the interface between the WC-based cemented carbide and the TiCN-based cermet has an average layer thickness of less than 5 μm between the WC-based cemented carbide and the TiCN-based cermet In the meanwhile, when the average layer thickness exceeds 200 μm, the brittleness of the interface layer becomes apparent, and the possibility of becoming the base point of the crack increases. The layer thickness is 5 to 200 μm.
The component composition and the average layer thickness of the interface layer are mainly the holding temperature and the holding temperature in the cooling process during sintering according to the component composition of the WC-based cemented carbide and the component composition of the TiCN-based cermet adjacent thereto. It depends on the time.

WC-based cemented carbide layer constituting at least a part of the outer peripheral portion including the cutting edge:
The composite sintered body cutting tool according to the present invention has a TiCN-based cermet as a matrix, and a WC-based cemented carbide layer formed on at least a part of an outer surface including a cutting edge, for example, a rake face It contains at least an iron group metal component (eg, Co, Ni, Fe) as a component and WC as a hard phase component.
The binder phase component strongly bonds to the hard phase component and has the effect of improving the strength and toughness of the tool substrate, but the content of the iron group metal component which is the binder phase component (that is, the content of Co, Ni, Fe) If the total amount is less than 4% by mass, the desired effect can not be obtained. On the other hand, if the content exceeds 17% by mass, the wear resistance is reduced, so that it is a binder phase component. The content of the iron group metal component (that is, the total content of Co, Ni, and Fe) is desirably 4 to 17% by mass.
In addition, each component of Ti, Zr, Nb, Ta and Cr forms carbides, nitrides, carbonitrides and the like to increase the hardness of WC base cemented carbide and to improve the wear resistance. Therefore, it is preferable to add a small amount of these hard phase components. However, if the total content of these hard phase components exceeds 10% by mass (provided that it is converted as a metal component), the toughness will be lowered, so the allowable inclusion of each component of Ti, Zr, Nb, Ta and Cr The total amount is 10% by weight or less.

In addition, the thickness of the WC-based cemented carbide layer constituting at least a part of the outer peripheral portion including the cutting edge, for example, the rake face, is 0.03 to 0.3 times the thickness of the composite sintered body It is desirable to
This is because when the thickness of the WC-based cemented carbide layer is less than 0.03 times the thickness of the composite sintered body, the wear progresses to TiCN-based cermet when the wear progresses during cutting. When the thickness of the WC-based cemented carbide layer exceeds 0.3 times the thickness of the composite sintered body, the WC-based cemented carbide layer is easily broken. Since the compressive stress applied to the hard metal layer is reduced, not only the thermal crack resistance is lowered, but also the chipping resistance and the fracture resistance are lowered, and furthermore, the amount of W used can not be reduced either. The reason is that it does not fit the purpose of
Therefore, in the present invention, the thickness of the WC base cemented carbide layer is preferably 0.03 to 0.3 times the thickness of the composite sintered body.

Composition of TiCN-based cermet adjacent to WC-based cemented carbide layer:
The TiCN-based cermet adjacent to the WC-based cemented carbide layer used in the present invention is a cermet containing TiCN as the main hard phase component and iron group metal (eg, Co, Ni, Fe) as the main binder phase component.
When the other contained components are converted to metal component elements, W contains less than 15% by mass, Mo 2 to 15% by mass, Nb 2 to 10% by mass, and Cr 0.2 to 2% by mass, and For Co and Ni among the iron group metal components, the ratio of the Co content to the total content of Co and Ni is preferably 0.5 to 0.8 (where the atomic ratio).

The reason why the above-mentioned component composition is desirable for the TiCN-based cermet adjacent to the WC-based cemented carbide layer is as follows.
W:
As the content of W increases as the content in TiCN-based cermet increases, the characteristics of TiCN-based cermet approach WC-based cemented carbide, so sintering as a composite becomes easy, but as contained in the present invention, In the present invention, the W content is less than 15% by mass because it is a component element for which a reduction in amount is required.

Mo:
Mo is a component element having the function of enhancing the wettability between the hard phase and the binder phase and improving the sinterability in the TiCN-based cermet, but if the content is less than 2% by mass, the wettability improving effect On the other hand, when the content exceeds 15% by mass, Mo dissolves in the hard phase to lower the strength and the toughness, so the content of Mo is set to 2 to 15% by mass.

Nb:
Nb has the effect of improving the high temperature oxidation resistance of TiCN-based cermets, but when the content is less than 2 mass% or exceeds 10 mass%, the high temperature oxidation resistance improvement effect is reduced Therefore, the content of Nb is set to 2 to 10% by mass.

Cr:
Cr has the effect of bringing the sintering temperature of the TiCN-based cermet closer to that of the WC-based cemented carbide, but if the content is less than 0.2% by mass, the effect is not sufficient, while the content is 2 When the content is more than% by mass, a Cr ₃ C ₂ free phase precipitates to reduce the toughness of the sintered body, so the content of Cr is set to 0.2 to 2% by mass.

Co:
Co is an iron group metal component and is a binder phase component in a TiCN-based cermet, but in relation to Ni which is also an iron group metal component, the content ratio of Co to the total content of Co and Ni (Co / It is desirable that (Co + Ni)) be in the range of 0.5 to 0.8 (in atomic ratio).
When sintering the composite of TiCN-based cermet and WC-based cemented carbide as the content ratio of Co (Co / (Co + Ni)) to the total content of Co and Ni is less than 0.5, TiCN-based The Ni component in the cermet diffuses into the WC base cemented carbide and lowers the high temperature hardness of the WC base cemented carbide, while the content ratio of Co to the total content of Co and Ni (Co / (Co + Ni) When it exceeds 0.8, the toughness of the TiCN-based cermet may be lowered, which may cause breakage of the composite sintered body.
Therefore, with regard to Co and Ni which are components contained in the TiCN-based cermet, the content ratio of Co (Co / (Co + Ni)) to the total content of Co and Ni is 0.5 to 0.8 (however, the atomic ratio) Within the range of).

The preferred component composition of the TiCN-based cermet adjacent to the WC-based cemented carbide layer is as described above, but the TiCN-based cermet does not have to be constituted as a whole of the above component composition.
That is, as shown in FIGS. 1 (b) and 2 (b), the TiCN-based cermet can be formed as a laminate of a plurality of TiCN-based cermet layers (two or more layers).
1 (b) and 2 (b) show an example in which the TiCN-based cermet is formed as a laminate of two layers of "TiCN-based cermet layer 1" and "TiCN-based cermet layer 2". The base cermet can be configured as a laminate of three or more TiCN-based cermet layers.
Here, with regard to the TiCN-based cermet layer in contact with the WC-based cemented carbide layer (that is, "TiCN-based cermet layer 1" shown in FIG. 1 (b) and FIG. 2 (b)), its component composition is determined as described above Although it is desirable, a TiCN-based cermet layer not directly in contact with the WC-based cemented carbide layer (ie, “TiCN-based cermet layer 2” shown in FIG. 1 (b) and FIG. 2 (b)) is usually used. The component composition of the TiCN-based cermet may be used.
With regard to the components usually contained in the TiCN-based cermet, such as ZrC, TaC, etc., these can be contained in the TiCN-based cermet (layer) of the present invention as long as the amount is within the normally contained range. .
In addition, the W content is preferably 8% by mass or less, more preferably 4% by mass or less, whereby the TiCN-based cermet (layer) is not deteriorated without deteriorating the cutting performance of the composite sintered body cutting tool. Since the W content contained in) can be further reduced, the effect of reducing the amount of W used is increased.

Hard coating layer:
The composite sintered body cutting tool of the present invention is as it is, by forming at least a part of the outer peripheral part including the cutting edge of the composite sintered body, for example, the rake face, by the WC base cemented carbide layer described above. Although it can be used as a cutting tool, it is possible to cover the surface of a WC-based cemented carbide layer by physical vapor deposition, chemical vapor deposition or the like, for example, by coating a hard coating layer such as a composite nitride layer of Ti and Al. The performance as a cutting tool can be further enhanced.
As the hard covering layer, not only a composite nitride layer of Ti and Al, but also a nitride layer of Ti, a carbide layer, a carbonitride layer, a composite nitride layer of Al and Cr, an Al ₂ O ₃ layer, etc. The various hard coating layers already known can be coated as a single layer or as a stack of several layers, respectively.

The composite sintered body cutting tool according to the present invention comprises a composite sintered body of a TiCN-based cermet and a WC-based cemented carbide, is an interface between the WC-based cemented carbide layer and the TiCN-based cermet, and the interface Since an interface layer having a predetermined layer thickness and component composition is formed on the WC-based cemented carbide layer side, the bonding strength between the WC-based cemented carbide layer and the TiCN-based cermet can be enhanced. An alloy that exerts intermittent high-impact mechanical high load and high thermal load on the cutting edge even if the amount of tungsten used is reduced and the layer thickness of the WC base cemented carbide layer is reduced In wet interrupted cutting of steel or the like, occurrence of peeling at the interface between the WC-based cemented carbide layer and the TiCN-based cermet is suppressed.

Furthermore, when the TiCN-based cermet is composed of two or more layers and the TiCN-based cermet layer adjacent to the WC-based cemented carbide layer is composed of a layer adjusted to a specific component composition, the bonding strength is high. In addition to the prevention of delamination at the interface due to the presence of the interface layer, it is possible to apply a large compressive stress to the WC-based cemented carbide layer, so intermittent high-impact mechanical high load and thermal on the cutting edge In wet interrupted cutting of alloy steels and the like where various high loads act, the occurrence of thermal cracking is prevented, and excellent over long-term use without causing abnormal damage caused by the occurrence of peeling, thermal cracking, etc. Cutting performance is exhibited.

The general | schematic longitudinal cross-section schematic diagram of the composite sintered compact cutting tool of this invention is shown, (a) shows one example of the composite sintered compact cutting tool of this invention, (b) shows multiple layers of TiCN based cermets. The other example of the compound sintered compact cutting tool of this invention comprised by (two layers) is shown. The general | schematic longitudinal cross-section schematic diagram of the composite sintered compact cutting tool of this invention by which the hard coating layer was provided in the surface of WC base cemented carbide layer is shown, (a) is the composite sintering shown to Fig.1 (a). In a body cutting tool, a composite sintered body cutting tool in which a hard coating layer is provided on the surface of the WC base cemented carbide layer is shown, and (b) is a composite sintered body cutting tool shown in FIG. 12 shows a composite sintered body cutting tool in which a hard coating layer is provided on the surface of the WC-based cemented carbide layer. (A) shows an example of the longitudinal cross-sectional SEM image of the compound sintered body cutting tool of this invention, (b) shows the elements on larger scale.

  Hereinafter, the present invention will be specifically described based on examples.

First, a WC-based cemented carbide raw material powder having an average particle diameter of 0.5 to 3 μm of the composition shown in Table 1 is prepared.
Further, TiCN-based cermet raw material powder having an average particle diameter of 0.5 to 3 μm of the composition shown in Table 2 is prepared.
The WC-based cemented carbide raw material powder and the TiCN-based cermet raw material powder were laminated and pressed with a die for material of ISO insert shape CCGT120408 in a combination shown in Table 3, to produce inventive composite molded bodies 1 to 12.
The composite molded bodies according to the present invention 1 to 12 produced according to the present invention are WC base cemented carbide raw material powders and one kind of TiCN based cermet raw material powders according to the present invention, and WC base cemented carbide raw material powders It is this invention compound molded object 7-12 using two types of TiCN-based cermet raw material powder of the raw material powder for TiCN-based cermet layer 1 formation, and the raw material powder for TiCN-based cermet layer 2 formation.
In the composite molded product of the present invention, the WC-based cemented carbide layer is disposed on the rake face side surface, but may be disposed such that the WC-based cemented carbide layer is present on the flank face surface. There is no problem at all.

Subsequently, the composite molded bodies 1 to 12 of the present invention were sintered to produce inventive sintered bodies 1 to 12 of the present invention.
The sintering conditions are as follows in each case.
When raising the temperature of the composite molded body to the sintering temperature, the temperature is raised from room temperature to 1280 ° C. at a temperature rising rate of 5 ° C./min, and the temperature range from 1280 ° C. to 1380 ° C. in which the liquid phase appears is any time Also, the temperature is elevated at a high rate of 30 ° C./min or more, the temperature is increased at a rate of 5 ° C./min from 1380 ° C. to 1420 ° C., 1420 ° C. in a 0.1 kPa nitrogen atmosphere. After sintering by holding at sintering temperature for 1 hour, in the cooling process, a heat treatment was performed to maintain the temperature range of 1330 ° C. to 1370 ° C. for 0.8 hr to 1.5 hr, and then cooled to room temperature.
The heat treatment conditions are shown in Table 3.
As a result of this sintering, it consists of WC base cemented carbide and TiCN base cermet, and is an interface between the WC base cemented carbide layer and the TiCN base cermet and from the interface to the WC base cemented carbide layer side. The formed composite sintered body of the present invention was produced.
Next, with respect to the present invention composite sintered bodies 1 to 12 obtained above, the WC base cemented carbide layer is used as a rake face, the cutting edge is honed with R = 0.04, and a composite sintered body cutting tool having a CCGT 120408 shape 1 to 12 (hereinafter referred to as inventive tools 1 to 12) were produced.

FIG. 3 (a) shows an example of an SEM image in the vicinity of the interface between the WC base cemented carbide layer of the present invention tool and the TiCN based cermet, as is also apparent from FIG. 3 (b) which is a partially enlarged view thereof. In the tool according to the present invention, the interface layer is an interface between the WC base cemented carbide layer and the TiCN base cermet, and from the interface to the WC base cemented carbide layer side (in the figure, the average layer thickness is 60 μm) Is formed.

The vertical section perpendicular to the interface between the WC-based cemented carbide layer and the TiCN-based cermet of the tools 1 to 12 according to the present invention uses the electron beam microanalyzer from the WC-based cemented carbide layer side to the TiCN-based cermet across the interface. Linear analysis in the direction, and containing W, Mo, Co, Ni, and a total content of W and Mo is 0.8 to 1.2 times (but an atomic ratio) of the total content of Co and Ni The location where the phase was present was defined as the interface layer, and the interface between the WC-based cemented carbide layer and the interface layer and the interface between the TiCN-based cermet and the interface layer were identified. Subsequently, the component composition of the WC base cemented carbide layer, the component composition / component ratio in the mixed phase, and the composition analysis of the TiCN base cermet are determined, and the average value of 10 points measurement is determined to determine the content of each component. Also, the composition ratio of W, Mo, Co, and Ni in the mixed phase, and the composition ratio of Co and Ni in the TiCN-based cermet were calculated. Also, measure the distance between the interface between WC base cemented carbide layer and interface layer, the interface between interface layer and TiCN base cermet, and the interface between these layers in the direction perpendicular to the interface, and conduct 10 measurements at 50 μm intervals parallel to the interface. The interface layer thickness was obtained by taking the average of them.
Furthermore, the width of the interface layer of 200 μm was image-processed, the result of composition analysis was compared with it, WC particles were identified, and the area% of WC particles and the area% of mixed phase were measured.
Tables 5 and 6 show these values.

In addition, the thickness of each WC-based cemented carbide layer with respect to the total thickness of the tool 1 to 12 of the present invention (note that the total thickness of the insert of CCGT 120408 shape is defined as 4.76 mm according to JIS standard) In order to obtain the ratio, the thickness of the WC-based cemented carbide layer is observed using a scanning electron microscope and an electron beam microanalyzer, and the WC-based cemented carbide layer from the interface between the WC-based cemented carbide layer and the interface layer The distance to the surface is measured at five different points, and this is averaged to obtain the thickness of the WC-based cemented carbide layer, which is divided by 4.76 mm to obtain (the thickness of the WC-based cemented carbide layer) / The value of (the thickness of the composite sintered body) was calculated.
Tables 5 and 6 show these values.

Next, for the tools according to the present invention 4 to 6 and 10 to 12, composite nitrides of Ti and Al (note that the contents of Ti and Al are respectively determined by arc ion plating on the surface of the WC base cemented carbide layer) A hard covering layer consisting of 50 at% was vapor deposited.
Tables 5 and 6 show the layer thicknesses of vapor deposited hard coating layers for the inventive tools 4 to 6 and 10 to 12.
Incidentally, when the inventive tools 1 to 12 correspond to FIGS. 1 and 2, the inventive tools 1 to 3 have the structures shown in FIG. 1A, and the inventive tools 4 to 6 have FIG. 2A. It can be said that the structure of the present invention tool 7 to 9 has the structure shown in FIG. 1 (b), and the present invention tools 10 to 12 have the structure shown in FIG. 2 (b).

For comparison, the WC-based cemented carbide raw material powder having the composition shown in Table 1 and the TiCN-based cermet raw material powder having the composition shown in Table 2 are laminated and pressed in the combinations shown in Table 3, and Comparative Example composite molded body 1 to 1 12 was produced.
Comparative example composite compacts 1 to 12 were all manufactured using WC-based cemented carbide raw material powder and one kind of TiCN-based cermet raw material powder.
Next, this comparative example composite molded body was sintered under the following conditions to prepare comparative example composite sintered bodies 1 to 12.
Comparative Example When raising the temperature of the composite compacts 1 to 12 to the sintering temperature, the temperature is raised from room temperature to 1280 ° C. at a rate of 5 ° C./min, and the liquid phase appears from 1280 ° C. to 1380 ° C. In the temperature range, the temperature is raised at a high rate of 30 ° C./min or more, and the temperature is increased at a rate of 5 ° C./min from 1380 ° C. to 1420 ° C. After sintering by holding at a sintering temperature of 1420 ° C. for one hour, a part of the sintered body is held for a certain time in a temperature range of 1300 ° C. to 1400 ° C., and then cooled to room temperature, and the comparative example composite sintered The bodies 1 to 12 were prepared. However, the heat treatment during cooling of the composite sintered body of the comparative example does not include the heat treatment at a temperature range of 1330 ° C. to 1370 ° C., which is the holding condition of the composite sintered body of the present invention, and 0.8 hr to 1.5 hr. .
That is, the comparative example composite sintered bodies 1 to 12 of the present invention are characterized in that the heat treatment for holding for 0.8 hr to 1.5 hr is not performed in the temperature range of 1330 ° C. to 1370 ° C. in the cooling process during sintering. The manufacturing conditions are different from the composite sintered body cutting tools 1 to 12 in the above.
Next, with respect to the obtained comparative example composite sintered bodies 1 to 12, the WC base cemented carbide layer is used as a rake face, and the cutting edge is honed with R = 0.04 to obtain a composite sintered body cutting tool 1 having a CCGT 120408 shape. 12 (hereinafter referred to as comparative example tools 1 to 12) were produced.

Subsequently, in the same manner as in the case of the inventive tools 1 to 12, with respect to the comparative example tools 1 to 12, using the electron beam microanalyzer, the component composition of the WC base cemented carbide layer, the component composition / component ratio in the mixed phase The composition analysis of TiCN and TiCN based cermets is performed, and the content of each component is determined by obtaining the average value of 10 points measurement, and the composition ratio of W, Mo, Co, Ni in the mixed phase, TiCN based cermet The composition ratio of Co and Ni was calculated.
Furthermore, the area% of WC particles in the interface layer and the area% of the mixed phase were measured.
Furthermore, the thickness of the WC-based cemented carbide layer was observed with an optical microscope, the thickness was measured at five different points, and the thickness was averaged to obtain the thickness of the WC-based cemented carbide layer. The value of (the thickness of the WC-based cemented carbide layer) / (the thickness of the composite sintered body) was calculated by dividing the value by 4.76 mm.
Table 7 shows these values.

In addition, for comparative tools 4 to 6 and 10 to 12, composite nitrides of Ti and Al (note that the contents of Ti and Al are respectively determined by arc ion plating on the surface of the WC base cemented carbide layer) A hard covering layer consisting of 50 at% was vapor deposited.
Table 7 shows the thickness of the vapor deposited hard coating layer.

Next, with respect to the present invention tools 1 to 12 and the comparative example tools 1 to 12,
Work material: JIS · SCM440 block,
Cutting speed: 315 m / min. ,
Notch: 1.0 mm,
Feeding: 0.12 mm / rev. ,
Cutting time: A wet milling cutting test of an alloy steel was conducted under a condition of 14 minutes to measure the flank wear amount, the cutting time to the end of the life, and observe the wear of the cutting edge.
Furthermore, the values of (thickness of WC-based cemented carbide layer) / (thickness of composite sintered body) shown in Tables 5 to 7 for the inventive tools 1 to 12 and the comparative example tools 1 to 12 are as follows: In each tool, it was not laminated with the cermet, and the used W amount reduction rate (mass%) from the case where the whole was WC base cemented carbide was calculated.
Table 8 shows these results.

From the results shown in Tables 5 and 8, the composite sintered body cutting tools 1 to 6 according to the present invention are the interface between the WC-based cemented carbide layer and the TiCN-based cermet, and Since an interface layer having a predetermined layer thickness and component composition is formed on the hard metal layer side and the bonding strength between the WC base cemented carbide layer and the TiCN base cermet is enhanced, the WC base cemented carbide layer and the TiCN base cermet It can be seen that the occurrence of peeling at the interface is suppressed and no abnormal damage occurs.
Furthermore, from the results shown in Tables 6 and 8, the composite sintered body cutting tools 7 to 12 according to the present invention can prevent peeling at the interface due to the presence of the interface layer with high bonding strength, It is found that the TiCN-based cermet is composed of a plurality of layers of two or more layers, and it becomes possible to apply a large compressive stress to the WC-based cemented carbide layer, thereby preventing the occurrence of peeling and the occurrence of thermal cracks. .
Therefore, the composite sintered body cutting tools 1 to 12 according to the present invention can reduce the amount of tungsten, which is a rare metal, and machine the cutting edge even if the layer thickness of the WC-based cemented carbide layer is reduced. Cutting performance during long-term use without causing abnormal damage caused by peeling or thermal cracking in wet interrupted cutting of alloy steels etc. where structurally high load and thermal high load act. Is demonstrated

  On the other hand, according to the results in Tables 7 and 8, the composite sintered body cutting tools 1 to 12 of the comparative example are the interface between the WC-based cemented carbide layer and the TiCN-based cermet, and Since the interface layer specified in the present invention is not formed from the interface to the WC-based cemented carbide layer side, any abnormal damage resulting from the occurrence of peeling, thermal cracking, etc. will all extend the service life in a short time It is clear.

The cutting tool of the present invention made of a composite sintered body can reduce the use amount of tungsten, which is a rare metal, and also can generate thermal load by intermittent high-impact mechanical high load on the cutting edge and heating and cooling cycles. Even when used in wet interrupted cutting where high load acts, it has excellent peel resistance and heat crack resistance, and exhibits excellent cutting performance over long-term use without generating abnormal damage such as chipping, chipping or peeling. Energy saving and cost reduction of the cutting process.

Claims (5)

In a composite sintered body cutting tool comprising a composite sintered body of a TiCN based cermet and a WC based cemented carbide,
(A) At least a part of the surface of the outer peripheral portion including the cutting edge of the composite sintered body cutting tool is composed of a WC-based cemented carbide layer,
(B) An interface layer having an average layer thickness of 5 to 200 μm is formed on the WC-based cemented carbide layer side from the interface between the WC-based cemented carbide layer and the TiCN-based cermet,
(C) The interface layer is composed of WC particles occupying 5 to 50 area% and a mixed phase occupying 50 to 95 area%,
(D) The total content of W and Mo present in the mixed phase is 0.8 to 1.2 times (in atomic ratio) the total content of Co and Ni present in the mixed phase Composite sintered body cutting tool characterized in that.   WC-based cemented carbide containing at least 4 to 17% by mass of an iron group metal component as a binder phase component and at least WC as a hard phase component at least a part of the rake face including the cutting edge of the composite sintered body cutting tool The composite sintered body cutting tool according to claim 1, characterized by comprising an alloy layer.   The composite sintered body according to claim 1 or 2, wherein the thickness of the WC-based cemented carbide layer is 0.03 to 0.3 times the thickness of the composite sintered body cutting tool. Cutting tools.   The TiCN-based cermet is composed of two or more TiCN-based cermet layers, and the TiCN-based cermet layer adjacent to the interface layer of the WC-based cemented carbide layer contains the content of the component of the cermet as the metal component. In terms of proportion, at least 4 to 25 mass% of iron group metal component, less than 15 mass% of W, 2 to 15 mass% of Mo, 2 to 10 mass% of Nb, 0.2 to 2 mass% of Cr And the Co content relative to the total content of Co and Ni is 0.5 to 0.8 times (with an atomic ratio) with respect to Co and Ni which are iron group metal components. The composite sintered body cutting tool according to any one of claims 1 to 3. The composite according to any one of claims 1 to 4, wherein a hard coating layer is formed on the surface of the WC-based cemented carbide layer including at least the cutting edge of the composite sintered body cutting tool. Sintered cutting tools.