JPS6021352A - Cermet for tool and its production - Google Patents

Abstract

PURPOSE:To provide a cermet having excellent characteristics as a tool by specifying the compsn. consisting of a solid soln. composed of composite metallic carbonitride of Ti and W and a composite solid soln. composed of MgO-Si3N4- Al2O3 as a hard phase forming component and W, etc. as a bond phase forming component. CONSTITUTION:A green compact consisting of 10-65wt% a solid soln. composed of composite metallic carbonitride of Ti and W and, if necessary, >=1 kind among 5a group metals of periodic table, about 0.5-10% MgO, about 1-20% Si3N4, about 1-20% Al2O3 and the balance W is sintered in a temp. range of about 1,800-2,300 deg.C in a vacuum or inert gaseous atmosphere. The cermet for a cutting tool and hot working tool which consists of 10-65% the solid soln. composed of the composite carbonitride of Ti and W and, if necessary, >=1 kind among 5a group metals of periodic table as a hard phase forming component, 1-40% the composite solid soln. composed of MgO-Si3N4-Al2O3 likewise as the hard phase forming component and the balance W and inevitable impurities as a bond phase forming component and which is highly resistant to wear, plastic deformation and impact is thus obtd.

Description

Detailed Description of the Invention The present invention has high toughness and hardness, as well as excellent wear resistance, plastic deformation resistance, and impact resistance. Cutting tools used for cutting and heavy cutting such as high-speed 9 cutting and deep cutting, as well as hot rolling rolls, hot drawing rolls, hot compression dies, hot forging dies, and hot extrusion punches. The present invention relates to a cermet that exhibits excellent performance when used as a hot working tool that is exposed to high temperatures for a relatively long period of time, and a method for producing the same.

In recent years, high-speed cutting and high-feed cutting have been considered in order to improve machining efficiency, but increasing the cutting speed or feed rate increases the temperature of the cutting tool's cutting edge and causes the cutting edge to wear out. In many cases, plastic deformation caused by high temperatures leads to the end of the service life.

However, the hard phases currently in practical use are mainly tungsten carbide (hereinafter referred to as WC) and titanium carbide (
We-based cemented carbide (hereinafter referred to as TIC), and the binder phase is mainly composed of iron group metals.The we-based cemented carbide TIC-based sert suddenly softens when the cutting edge temperature exceeds 1000°C. In order to become these WCC cemented carbide T
Not only IC-based cutters but also those with a hard coating layer formed entirely on their surfaces, the usage conditions are limited to a cutting edge temperature of slightly over 1000°C.

In addition, a cermet has been proposed in which the hard phase is composed of a composite metal carbonitride solid solution of T1 and W (hereinafter referred to as (Ti, W)C!N), while the binder phase is composed of a W-Mo alloy. Attempts have been made to use cermet as a cutting tool for high-speed cutting and heavy cutting, but this conventional cermet has poor sinterability and is used as a raw material powder (Ti, W).
) Because the C concentration in the ON powder is relatively high, a part of it reacts with a part of the W powder during sintering, resulting in brittle W2C'f.
Currently, the impact resistance is poor due to the presence of W2C, and therefore the cutting performance is not sufficiently satisfactory.

Therefore, from the above-mentioned viewpoint, the present inventors have developed a cutting tool that can be used as a cutting tool for high-speed cutting and heavy-duty cutting of steel, etc., which requires particularly excellent plastic deformation resistance, impact resistance, and wear resistance. As a result of research to develop a material suitable for , the weight department found that (Ti, W)ON,! , or T1, W, and one or more metals of group 5a of the periodic table of elements (hereinafter these metals are referred to as M5). , M5) ON): 10-65 Magnesium oxide (hereinafter referred to as MgO): 0.5-10
H, Silicon nitride (hereinafter referred to as Si3N4): 1 to 20 units, Aluminum oxide (hereinafter referred to as M2O3): 1 to 20 units, W: remainder, A green compact having a blending composition consisting of the following is heated in a vacuum. Alternatively, when sintered in an inert gas atmosphere at a high temperature within the range of 1 soo to 2300 °C, (Ti, W)
ON or (Ti, W, M5) ON: 10~
65%, MgO, Si3N4, All+203(7) composite solid solution (hereinafter referred to as MgO-5i3N4-Ive203 solid solution): 1 to 40%, W and unavoidable impurities: remaining 9. In the resulting cermet, during sintering, MgO is mainly converted into (Ti, W)C! N or (T11 W *
"s) ・Reacts with the C component in CN to reduce the C component in these composite metal carbonitrides (in this case, MgO
The sinterability is significantly improved, and the formation of brittle W2C is completely suppressed, making it possible to ensure excellent impact resistance. Furthermore, since the main part of residual MgO that did not participate in the above reaction, the MgO-5i3N4-uzo3 solid solution formed by Si3N4 and M2O3 exists as a dispersed phase, it has even better wear resistance. Moreover, the above (
Since Ti, W) ON or (Ti, W, M5) ON ensures excellent plastic deformation resistance and wear resistance, it is used as cutting tools for high-speed cutting and heavy cutting, and as hot working tools. They found that when used as a compound, it will exhibit excellent performance over a long period of time.

This invention was made based on the above knowledge, and the reason why the component composition was limited as described above will be explained below.

(a) (Ti, W) ON or (Ti, W,
M5) ON These components have the effect of improving the wear resistance and plastic deformation resistance of cermet, but if their content is less than 10%, a skeleton may be formed in the W matrix forming the binder phase. On the other hand, if the content exceeds 65 mm, the amount of W forming the matrix will be relatively reduced and the toughness will deteriorate. From, its content is 10~
It was set at 65%.

(b) MgO-Si3N4-M2O3 solid solution Most of the MgO constituting this solid solution is formed during sintering (T
i,, W) CN dimensions or (Ti, W, M5) C
It reacts with the C component in N to reduce the amount of C in the cermet, thereby preventing the formation of brittle W2C and improving the sinterability, which improves the impact resistance of the cermet. The remaining main part is MgO-5i3N.
4-U203 solid solution is formed and has the effect of significantly improving the wear resistance of cermet, but the content is 1φ
If it is less than 4, the desired stiffness and wear resistance improvement effect cannot be obtained;
If the content exceeds 0, the impact resistance of the cermet will deteriorate.
It was decided that there would be 40 people in charge.

(c) W and unavoidable impurities W&'i, most of which are present as a binder phase, are strongly bonded to the dispersed phase and have the effect of improving the impact resistance of the cermet. In addition, as inevitable impurities, Mo, Or
, Fe, 'Ni, Co, Re, Pt, and Pd. Next, the case of containing one or more of the following will be specifically explained with reference to embodiments of the cermet for tools of the present invention.

Example 1 As raw material powder, average particle size: 1.5μ? (TiO,85wo,15) (+:!0.
7ON0.30) powder (the numbers in parentheses indicate the atomic ratio; the same applies hereinafter; also shown as (Ti, W)ON in Table 1), the same 1.2 μm complete solid solution (T:io7sw
o, tsTao, to) (C07ON0.30)
Powder (indicated by (Ti, W, Ta) CN in Table 1), MgO powder of 0.411m, Q, f31tm
of Si3N4 powder, 0.5 ptn of M2O3 powder,
and the same 0.8 μm W powder were prepared, and these raw material powders were blended into the composition shown in Table 1, pulverized and mixed in a ball mill for 72 hours, dried, and then
By press-forming at a pressure of 5 kg/- to form a green compact, and then sintering this green compact in a nitrogen atmosphere of 200 torr at the temperature shown in Table 1 for 2 hours, Present invention cermets 1 to 21 and comparative cermet 1 having the component compositions shown in Table 1
- 6 were produced respectively. In addition, comparison cermets 1 to 6
is the component content of any of the constituent components (
In Table 1, those marked with an asterisk (*) have compositions that are outside the scope of this invention.

Regarding the resulting cermets 1 to 21 of the present invention and comparative cermets 1 to 6, the Rockwell hardness (A school) and transverse rupture strength were measured, and a cutting tip with a gold shape of psNP432 was cut out. Workpiece 442 S N CM -8 (Hardness °H+, +22
0), cutting speed: 200 +y+/min.

Feed: 0.3 Tnm/rev, Depth of cut: 2m
q, cutting time: iom=, high-speed continuous cutting test under the conditions, and work material: SRO
M-8 (hardness: HB250), cutting speed: 150 m
An intermittent cutting test was conducted under the following conditions: 7ml 71° feed: 0.4 mm/rev, depth of cut 3mm1, cutting time: 3ml1n, and in the above high-speed continuous cutting test, the flank wear width and rake face wear depth of the cutting edge were measured. In addition, in the above-mentioned interrupted cutting test, the number of cutting edges in which chipping occurred at the cutting edge among the 10 test cutting edges was measured. The results of these measurements are shown in Table 2. For comparison purposes, ■SO's P10 grade WCC cemented carbide cutting tip (hereinafter referred to as conventional cutting tip 1) and Tic! −
A TIC-based Sursut cutting tip (hereinafter referred to as conventional cutting tip 2) having a composition of I Q %Mo -15%N1 (the above is based on weight, the below is based on weight) was also cut under the above cutting conditions. Tests were conducted and the results are also shown in Table 2.

As is clear from the results shown in Table 2, all of the cermets 1 to 21 of the present invention have high hardness and high toughness, and exhibit excellent wear resistance and impact resistance in all cutting tests. On the other hand, Comparative Cermet 1, which does not contain MgO, has inferior sintering properties and impact resistance, and therefore defects occur on all cutting edges, especially in interrupted cutting tests, and (
Ti, W)C! Comparative cermet 2, whose N content was higher than the range of this invention, showed relatively good wear resistance, but had poor toughness, so more than half of the cutting edges were broken in the interrupted cutting test. There has occurred. Also, S13
Comparative cermets 3,4 containing neither N4 nor M2O3 and MgOf with any of these components
Comparative cermets 5 and 6 that do not contain MgO-
Since no Si3N4-A, e203 solid solution was formed, the wear resistance was poor and the impact resistance was also poor.

Further, the conventional cutting tips 1 and 2 have poor wear resistance and impact resistance, and exhibit extremely poor cutting performance.

Example 2 In addition to the raw material powder used in Example 1, as raw material powder,
(Tio, '5
oWo, zo ) (CO,?ON0.30) powder (
In Table 3, (Ti,W)ON-■) have the same 1.5 pyn f as a complete solid solution (TiO,?).
OW0.30) (C0,7ON0.30) powder (indicated by (Ti,W)C!N-■ in Table 3).

Same 1.8μ? n(Ti0.75W0.25) (c
o, 5oNo, zo) powder (Table 3 shows (Ti, W)
CN-■), 2.0 pm (Ti0.80
W0.20) (Co, aONo, 40) powder (shown as (Ti, W)CN-■ in Table 3), 1.2 pm
(Tio7s・Wo, 15V0.10) (C0,
7ON0.30 ) powder (Table 3 shows (Ti.

W, V) aN), 1.8 μm (Ti 0.7
5Wols ・Nbo, to) (C0,7ON0
．． 30) powder (Table 3 shows (Ti,,W).

Nb)ON), and 185μ? n's (Tio
, as・Wo, zsTaolo) (C0,7ON0
．． 30) Powder (Table 3 shows (Ti).

W, Ta) ON) were prepared, and these raw material powders were blended into the composition shown in Table 3, and then wet-pulverized and mixed under the same conditions as in Example 1, dried, and molded. to make a green compact, and then this green compact f760
By sintering in an Ar gas atmosphere of torr and maintaining the temperature shown in Table 3 for 2 hours,
Cermets 22 to 36 of the present invention and comparative cermets 7 to 11f having the same compositions shown in Table 3 were manufactured, respectively.

In addition, comparison semetsu]・7 to 11 all have the content of one of the constituent components (*marked 1 in Table 3 (τj
) has a composition outside the scope of this invention.

Then, the resulting cermets 22 to 36 of the present invention
The hardness and transverse rupture strength of Comparative Cermets 7 to 11 were measured, and together with the WCC cemented carbide cutting tip (hereinafter referred to as conventional cutting step 3), the work material: SNCM-8 (hard) was measured. Cutting speed: 100 m/mln, Feed: 0.8 cylinder/r
ev,, Depth of cut: 4mm.

Cutting time: 10m1u.

High feed continuous cutting test under the conditions of and work material: S
NC! M-8 (hardness: H11250, cutting speed: 10
0m/tomo, feed: 0.45 mm/rev, depth of cut: 3m
m.

Cutting time: 3m1n.

An interrupted cutting test was conducted under the following conditions, and in the same manner as in Example 1, the flank wear width and rake face wear depth of the cutting edge, and the number of missing cutting edges were measured. These measurement results are also shown in Table 4.

From the results shown in Table 4, the present invention cermets 22 to 3
6 has high hardness and high toughness, and shows excellent cutting performance in continuous high-feed cutting and interrupted cutting, whereas conventional cutting tip 3 has particularly poor plastic deformation resistance, so it cannot be used in continuous high-feed cutting. In the cutting test, it became impossible to cut after 1 minute.

In addition, as seen in Comparative Cermets 7 to 13, if the content of any of the constituent components falls outside the range of the present invention, at least one of the properties of hardness and toughness becomes inferior. Moreover, it is clear that cutting tests also showed poor results in wear resistance, plastic deformation resistance, and impact resistance.

As mentioned above, the cermet of the present invention has high toughness and hardness, and also has excellent wear resistance, plastic deformation resistance, and impact resistance, so it can be used with steel etc. that require these properties. It shows excellent cutting performance when used as a cutting tool for high-speed cutting and heavy cutting, and is also suitable for hot rolling rolls, hot drawing rolls, hot compression dies, hot forging dies, and even hot extrusion punches. It has two useful properties in industry, such as exhibiting excellent performance over a long period of time even when used as a hot working tool that is exposed to high temperatures for a relatively long period of time.

Applicant: Mitsubishi Metals Corporation Agent Tomi 1) Kazuo and 1 other person

Claims (2)

[Claims] (1) A composite metal carbonitride solid solution of Tj and W as a hard phase forming component 10 to 65%, magnesium oxide also as a hard phase forming component,
Composite solid solution of silicon nitride and aluminum oxide: 1 to 4
1. A cermet for cutting tools and hot working tools, characterized in that it has a composition (parts by weight) consisting of W as a binder phase forming component, unavoidable impurities, and residues. (2) 10 to 65% of a composite metal carbonitride solid solution of T1, W, and one or more metals of Group 5a of the Periodic Table of the Elements as hard phase forming components. Magnesium oxide, which is also a hard phase forming component,
Composite solid solution of silicon nitride and aluminum oxide: 1 to 4
A cermet l-8 for cutting tools and hot working tools, characterized by having a composition (parts by weight) consisting of W as a binder phase forming component and residual unavoidable impurities.