JPH04116134A - Wc base sintered hard alloy excellent in toughness and sintered hard alloy coated with hard layer - Google Patents

Abstract

PURPOSE:To manufacture a WC base sintered hard alloy excellent in toughness and chipping resistance, in a WC base sintered hard alloy composed of a hard phase essentially consisting of WC and a bonding phase constituted of Co, by specifying the componental compsn. and structure of the hard phase. CONSTITUTION:In a WC base sintered hard alloy composed of a hard phase essentially consisting of WC and a bonding phase constituted of WC, the componental compsn. of the hard phase lies in the range obtd. by connecting A, B, C and D in a WC-TiC-TiN ternary diagram by straight lines. Furthermore, the structure of the hard phase is composed of the three phases a WC phase having 0.5 to 5.0mum average grain size, a double solid soln. carbon nitride phase of W and Ti having 0.5 to 3.0mum average grain size and a TiN phase having 0.5 to 3.0mum average grain size. Moreover, in the ternary diagram, A, B, C and D are points shown by A (by mol, 85% WC-2% TiC-13% TiN), B (45% WC-35% TiC-20% TiN), C (25% WC-15% TiC-60% TiN) and D (38% WC-2% TiC-60% TiN).

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides a cutting tool that has excellent heat cracking resistance, is resistant to breakage even when used in severe interrupted cutting such as milling, and has a long service life. The present invention relates to a WC-based cemented carbide and a hard layer-coated cemented carbide that can be manufactured.

[Conventional technology]

Generally, WC-based cemented carbide includes WC-Co based cemented carbide,
WC-(Ti, Ta, W)C-Co based cemented carbide etc. are known, and the above-mentioned WC-Co based cemented carbide is used as a cast iron cutting tool member and the above-mentioned WC(Tj, Ta, W)C- Co
Cemented carbides are known as steel cutting tools.

Up to now, many studies have been conducted and many proposals have been made regarding the above-mentioned WC-(Tj, Ta, W)C-Co based cemented carbide.

For example, Japanese Patent Publication No. 59-42067 discloses that the hard phase is mainly composed of WC, TiC, TaC, and NbC.

A cemented carbide containing one or more types of VC and containing Co as a binder phase, the average grain size of the WC being 3.
WC-based cemented carbide is described as having no solid solution carbide having an average grain size of 0.7 μm or less and exceeding 1 μm or no solid solution carbides.

Further, in JP-A-51-125013, the hard phase is composed of TiC, TiN, and WC, and these hard phases are Fc.
A cemented carbide formed by bonding group metals has been described, and the structure of this cemented carbide contains a WC phase, (Ti, W) (C,
N) The presence of a hard phase consisting of a phase force <S self-contained.

Furthermore, Japanese Patent Publication No. 61-41'J80 discloses that WC is the main component, TiN, TaC, NbC and (Ta,
Nb) One or more types of C and C.

It is described as a WC-based cemented carbide whose hard phase structure consists of three phases: WC, (Ti, W, Ta, Nb) (C, N) with an average grain size of 2 or less, and TiN. .

[Problem to be solved by the invention]

The WC-based cemented carbide described in the above-mentioned Japanese Patent Publication No. 59-420G7 certainly has improved chipping resistance compared to the conventional JIS standard P30 cemented carbide, but it does not have sufficient performance in milling with severe thermal shock. Not shown, and the above-mentioned Japanese Patent Application Laid-Open No. 51-12
The cemented carbide disclosed in Publication No. 5613 has a hard phase of (Tj, W)C
Composed of N and WC, the amount of nitrogen in the cemented carbide is (T1.W
) Since only the amount of nitrogen is contained in CN, the nitrogen content is small and the strength is insufficient.

Furthermore, the WC-based cemented carbide of the above-mentioned Japanese Patent Publication No. 84-41980, WC, and (Ti, W
Although it contains a hard phase consisting of three phases: , Ta, Nb) (C, N), and TiN, it still did not show sufficient performance for milling with severe thermal shock.

[Means to solve the problem]

Therefore, the inventors of the present invention conducted research to develop a WC-based cemented carbide for cutting tools that can sufficiently withstand milling, which is subject to severe thermal and mechanical shock, and as a result, developed WC7i! They found that a WC-based cemented carbide with even higher fracture resistance can be obtained by limiting the composition and structure of the hard phase constituting the cemented carbide within a specific range.

The present invention has been made based on this knowledge, and includes: (1) In a WC-based cemented carbide consisting of a hard phase mainly composed of WC and a binder phase of Co, the hard phase is as shown in FIG. It has a component composition within the range surrounded by straight lines connecting A, B, C, and D in the WC-TiC-TiN ternary system phase diagram, and has an average particle size of 0.
Tungsten carbide phase of 5-5.0 μm, average particle size: 0.
For composite solid solution carbonitride of W and Ti with a diameter of 5 to 3.0 μm, and a WC-based ultra-superstructure with excellent toughness that has a structure consisting of three phases: a titanium nitride phase with an average particle size of 0.5 to 3.0 μm. Hard alloy (2) In a WC-based cemented carbide consisting of a hard phase mainly composed of WC and a binder phase of Co, the hard phase is A in the WC-Tic-TiN ternary system phase diagram in Figure 1. In addition to the component composition within the range bounded by connecting B, C and D with a straight line, 20% by weight or less of M
(However, M represents one or two of Ta and Nb), has a component composition containing one or more of carbides, nitrides, and carbonitrides, and has an average particle size: Tungsten carbide phase of 0.5-5.0 μm, average particle size: 0.5-3.0 for composite solid solution carbonitride of W, Tj, and M, and average particle size: 0.5-3.0 μm. 0μ
This is a WC-based cemented carbide having excellent toughness and having a structure consisting of three phases of titanium nitride phases.

Each of the points A, B, C, and D in the WC-Tic-TiN ternary system phase diagram shown in Figure 1 above is A (WC: 85%, T
iC: 2%, TiN: 13%), B (WC: 45%, T
iC: 35%, T i N: 20%), C (WC
: 25%, TiC: 15%, TIN: 80%
), D (WC: 3g96. T i C: 2%,
T IN: fli096), (% is mol%
) can be specified.

The above-mentioned WC-based cemented carbide base of the present invention having excellent toughness,
The hard layer-coated superstructure of the present invention is further coated with a hard layer of one or more of Ti carbides, nitrides, oxides, borides, solid solutions thereof, and Al2O3 on the surface thereof. Hard alloys can be produced.

In order to manufacture the WC-based cemented carbide of the present invention, in addition to normal WC powder, TiN powder, and Co powder, a composite solid solution carbonitride powder of W and Tj [hereinafter referred to as (W, T
i) (W, Ti) (C.

N) The amount of nitrogen that can be added in a solid solution cannot exceed the nitrogen solid solubility limit of this solid solution.
When sintered in a high nitrogen atmosphere of 100 Torr or more, the hard phase structure has a WC phase with an average grain size of 0.5 to 5.0 μm, and a WC phase with an average grain size of 0.5 μm.
~3.0 (W, Ti) (C.

N) phase and average grain size: A WC-based cemented carbide with excellent toughness is obtained, consisting of three phases of TiN phase with a diameter of 0.5 to 3.0 um.When this cemented carbide is applied to cutting tools for milling, it has extremely high toughness. It was confirmed that it has thermal shock resistance and excellent fracture resistance.

In addition to the above raw material powder, TaC powder, NbC powder, (T
a, Nb) C powder, TaN powder, NbN powder, (Ta,
Nb) N powder, TaCN powder, NbCN powder, (Ta,
Nb) One or more types of (C, N) powder = 2
10% raw material powder added with 0% by weight or less together with Co powder
When sintered in a high nitrogen atmosphere of 0 Torr or more, (W, T1.M) (C,N) with an average particle size of 0.5 to 3 μm
phase (however, M is one or two of Ta and Nb)
WC with improved oxidation resistance and further improved performance.
It was confirmed that a base cemented carbide could be obtained.

Further, the WC-based cemented carbide of the present invention, V, Cr.

Even if one or more of carbides, nitrides, and carbonitrides of Mo 2 , Hf, and Zr are added in an amount of 5% by weight or less, no deterioration in performance is observed. Further, 50% by weight or less of the WC-based cemented carbide CO of the present invention is Ni or Fe.

Even if one or more types of AΩ are substituted, the properties of the WC-based cemented carbide of the present invention are not essentially impaired.

Next, the reason why the composition and structure of the WC-based cemented carbide of the present invention are limited as described above will be explained.

(a) The component composition of the hard phase is WC-TiC- in Figure 1.
The reason why A, B, C, and D of the TiN ternary system phase diagram are connected with a straight line and placed within the range is as follows: (1) In the range where TiN is less than the straight line AB, TiN
does not exist alone, or even if it exists, Ti
Since the average grain size of N is less than 0.5 knots, the rake face wear resistance of the cutting tool edge decreases. (ii) In the range where TiN increases beyond the straight line CD,
Even if sintered in a high nitrogen atmosphere, TiN decomposes during sintering, leaving many cavities in the sintered body and reducing impact resistance. (iii) Part of the WC is still sintered. to (W, Ti) (C,
N) and TiN to form a composite solid solution carbonitride of W and Ti, but in a range where WC is less than the straight BC, the WC phase existing alone decreases, and the toughness (impact resistance) of the alloy decreases. (Iv) In the range where TiC is less than the straight line AD, the wear resistance of the alloy decreases.

(b) The average particle size of the WC phase of the hard phase is 0.5 to 5. (
Jun, average particle size for composite solid solution carbonitride is 0.5-3,
The reason why the average grain size of the 0 and TiN phases is set to be within the range of 0.5 to 0.3 μm is because (1) If the average grain size of the wc phase is less than 0.5 μm, the rake face wear resistance However, the impact resistance also decreases.・5.0
If the average grain size of the (W, Ti) (C,N) phase is less than 0.5, the rake wear resistance decreases. 3
．． (iii) If the average particle size of the T i N phase is less than 0.5 μm, the rake face wear resistance of the cutting edge decreases, and if it exceeds 3.0 μm, the impact resistance decreases. This is due to reasons such as decreased performance.

〔Example〕

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

Example 1 The raw material powders were WC powder with an average particle size of 3.0 and (W, Ti) (C, N) powder (W, Ti) with an average particle size of 1.8.
:TiC:TiN=56:24:20. weight ratio), average particle size: 2. Low (W, Ti)C powder (WC: Ti
C-70: 30. weight ratio), average particle size: 1.5tI
n TiN powder, average particle size: 1.2t1frI Co
Powder, average particle size: 1.8μm TaC powder, average particle size: 1.9μm NbC powder, average particle size: 2.0urrI (Ta, Nb)C powder (T
a:Nb-90: 10. weight ratio), average particle size: 1.6 μn+ TaN powder, average particle size: 2.
2 μm NbN powder, average particle size: 1.5 times m TaCN powder (TaC:T
aN-90:10. Weight ratio), average particle size: 1.8 μm (Ta, Nb) (C, N) powder (TaC:TaN:NbC=80:10:10.weight ratio), average particle size: 2. 'aum HfC powder was prepared, and these raw material powders were blended as shown in Table 1,
The WC of the present invention was mixed and sintered under the conditions shown in Table 1.
Base cemented carbide ~18 and comparative WC base cemented carbide ~6 were produced.

Obtained WC-based cemented carbide of the present invention ~18 and comparative WCJ
! The structures of the hard phases of cemented carbide alloys 1 to 6 were examined and their grain sizes were also measured, and the results are shown in Table 1.

Next, these WC-based cemented carbide of the present invention ~ 18 and comparative W
C-base cemented carbide ~6 to ISO standard 5EEN42AFT
Each indexable tip in the shape of N1 was prepared,
Using these indexable inserts, workpiece material: SCM440 (hardness, HB220), cutting speed: 150m/ff1in, feed rate 0.3mm/
Blade, depth of cut: 3. Om+e.

Milling was performed twice on one indexable insert under the following conditions, and the time required to cause breakage was 7111j
The results were also shown in Table 1.

Furthermore, for comparison, a cutting test was conducted under the above conditions using a commercially available indexable insert made of P30 cemented carbide, and the results are also shown in Table 1.

Example 2 The surface of the indexable tip made of the WC-based cemented carbide of the present invention in Example 1 was coated with various hard layers shown in Table 2 by the usual CVD method and PVD method to obtain the hard layer coating of the present invention. Throwaway chips 1 to 9 were manufactured.

Furthermore, for comparison, commercially available P3 prepared in Example 1
The hard layer shown in Table 2 was coated on the surface of an indexable tip made of zero cemented carbide to prepare conventional hard layer coated indexable tips 1 and 2.

These hard layer coated indexable inserts are
CM440 (Hardness, HB220) Cutting speed: 200
m/m1n, Feed: 0.25mm/blade, Depth of cut: 3. O+n+a.

Milling was performed twice on one hard layer coated indexable tip under the following conditions, the time until breakage occurred was measured, and the average of the two times was calculated. These results are also shown in Table 2.

〔Effect of the invention〕

From the results in Table 1, it can be seen that the indexable insert made of the WC-based cemented carbide of the present invention has much better fracture resistance than the commercially available WC2J and indexable insert made of the cemented carbide. It can be seen from the above that all of the WC-based cemented carbides of the present invention have excellent toughness.

In addition, comparative WC having a structure that deviates from the conditions of this invention
The indexable insert made with the WC-based cemented carbide (values that deviate from the conditions of this invention are indicated with an asterisk) has a shorter time to breakage during milling than the comparative WC-based cemented carbide. It can be seen that the alloy toughness is low.

Furthermore, from the results in Table 2, it can be seen that the hard layer-coated indexable tip of the present invention, which is obtained by coating the hard layer on the indexable tip made of the WC-based cemented carbide of the present invention, is similar to the commercially available WC21.
! It can be seen that both of them have excellent fracture resistance compared to the conventional hard layer-covered indexable insert made of a hard layer coated indexable insert made of cemented carbide.

WC-Tic showing the range of It is.

TiN ternary system phase diagram 2. Mitsubishi Metals Co., Ltd. 1 other person 4,

[Brief explanation of the drawing]

Claims (4)

[Claims] (1) In a WC-based cemented carbide in which a hard phase mainly composed of WC is bonded by a binder phase consisting of Co, the component composition of the hard phase is the ternary system WC-TiC-TiN shown in Figure 1. The structure of the hard phase is within the range surrounded by straight lines connecting A, B, C, and D in the phase diagram, and the structure of the hard phase is a tungsten carbide phase with an average grain size of 0.5 to 5.0 μm; 0.5-3.0μm W and Ti
composite solid solution carbonitride phase, and average particle size: 0.5 to 3.
A WC-based cemented carbide with excellent toughness, consisting of three phases including a 0 μm titanium nitride phase. However, the above A, B, C and D are WC- in Fig. 1 above.
In the TiC-TiN ternary system phase diagram, A(WC:85
%, TiC: 2%, TiN: 13%), B (WC: 45
%, TiC: 35%, TiN: 20%), C (WC: 2
5%, TiC: 15%, TiN: 60%), D(WC:
38%, TiC: 2%, TiN: 60%) (the above is mol%). (2) In addition to the hard phase according to claim 1, 20% by weight or less of M (M represents one or two of Ta and Nb) among carbides, nitrides, and carbonitrides.
A tungsten carbide phase with an average particle size of 0.5 to 5.0 μm and a tungsten carbide phase of W, Ti, and M with an average particle size of 0.5 to 3.0 μm. Composite solid solution carbonitride phase and average particle size: 0.5 to 3.0
A WC-based cemented carbide with excellent toughness, characterized by having a hard phase consisting of three micrometer-sized titanium nitride phases. (3) On the surface of the WC-based cemented carbide having excellent toughness according to claim 1, one or more hard compounds selected from Ti carbides, nitrides, oxides, borides, and solid solutions thereof, and Al_2O_3. A hard layer coated cemented carbide with excellent toughness characterized by being coated with a layer. (4) On the surface of the WC-based cemented carbide having excellent toughness according to claim 2, one or more types of hard carbides, nitrides, oxides, borides of Ti, solid solutions thereof, and Al_2O_3 are added. A hard layer coated cemented carbide with excellent toughness characterized by being coated with a layer.