JPS5917176B2 - Sintered hard alloy with hardened surface layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sintered hard alloy having particularly excellent wear resistance and plastic deformation resistance.

Conventionally, sintered hard alloys generally include: (a) WCC cemented carbide containing tungsten carbide (hereinafter referred to as WC) as a main component; (b) titanium carbide (hereinafter referred to as TiC) and titanium nitride (hereinafter referred to as TiN). ), or cermet containing titanium carbonitride (hereinafter referred to as T1CN) as a main component; (c) aluminum oxide (hereinafter referred to as Al2O3);
Among these conventional sintered hard alloys, ceramics have a toughness that exceeds the above-mentioned WC when used as a cutting tool.
Since it is inferior to C cemented carbide and cermet, Al2
The excellent heat resistance, oxidation resistance, and welding resistance of O3 cannot be fully utilized, and therefore it is only put into practical use in a few limited fields.

In addition, most of the above cermets are mainly composed of TiC, but since TiC has inferior toughness and plastic deformation resistance compared to WC, this TiC-based cermet cannot be used during interrupted cutting under heavy loads. TiC-based cermets have the problem of being prone to chipping and plastic deformation when used for cutting hard and rigid materials. Therefore, in order to improve the toughness of TiC-based cermets, various carbides and The addition of nitrides has been considered, and although the toughness of the TiC-based cermet has been improved to some extent by the addition of these components, the current situation is that sufficient improvements have not been made in terms of wear resistance and plastic deformation resistance. .

On the other hand, although WCC cemented carbide is superior to the above cermet in terms of toughness, it is inferior in wear resistance.
When used for high-speed cutting of C cemented carbide, it exhibits significantly inferior cutting performance compared to the above-mentioned cermet.

In this way, the above WCC cemented carbide and cermet have
Each has its own merits and demerits, and none of them can be said to be a sufficiently versatile material, especially when used for cutting relatively hard work materials or for heavy cutting with a large load. There were many cases of wear and plastic deformation.

Therefore, from the above-mentioned viewpoint, the present inventors have obtained a sintered hard alloy that has significantly improved wear resistance and plastic deformation resistance compared to the conventional cermet and WCC cemented carbide. As a result of our research, we found that (a) nitrides, composite nitrides, carbonitrides, and composite carbonitrides of metals from groups 4a and 5a of the periodic table, as well as metals from groups 4a and 5a of the periodic table, as hard phase-forming components; same as 6a
One or two of the group consisting of composite carbonitrides of group metals
A green compact consisting of at least one raw material powder and one or more raw material powders of iron group metals as a binder phase forming component is placed in a carburizing gas atmosphere containing hydrocarbons such as CO and CH4. The material is heated below the temperature at which a liquid phase appears, followed by vacuum sintering, resulting in no bores (small pores).
Furthermore, a sintered hard alloy is obtained in which a hardened surface layer having a hardness distribution that increases continuously toward the surface is obtained, and the sintered hard alloy has excellent wear resistance and plastic deformation resistance. .

(b) One or more of the group consisting of carbides and composite carbides of metals of groups 4a, 5a and 6a of the periodic table is added to the sintered hard alloy in item (a) above as a hard phase forming component. When it is included, the thickness and hardness of the hardened surface layer in the sintered hard alloy can be adjusted.

(c) When the binder phase of the sintered hard alloy shown in the above αω terms and (b) terms contains one or more of the Cr group metals (Cr, Mo and W), The Cr group metal dissolves in solid solution in the binder phase made of the iron group metal, further improving the high temperature strength of the alloy and further improving the wettability with the hard phase during sintering. .

(d) When Al is included in the binder phase of the sintered hard alloy shown in the above items a), (b), and (c),
Fine intermetallic compounds of AA are formed in the binder phase, and the high temperature strength of the hardened surface layer of the sintered hard alloy is further improved.

The findings shown in sections (a) to (d) above have been obtained.

Therefore, the present invention has been made based on the above knowledge, and uses sintered hard alloys as (a) hard phase-forming components, 4a and 5a of the periodic table.

and one or more of the group consisting of carbides and composite carbides of group 6a metals (hereinafter referred to as hard surface layer adjusting components): 10 to 85.5%, (b) Also as a hard phase forming component, periodic rule One of the group consisting of nitrides, composite nitrides, carbonitrides, and composite carbonitrides of Group 43 and 5a metals, and composite carbonitrides of Group 4a and 5a metals and Group 6a metals in Table 1. or two or more (hereinafter referred to as hardened surface layer forming components): 9.5 to 85%, and if necessary, (c) one or two of the Cr group metals as a binder phase forming component. or more: 1-15%, (d) Also as a bonded phase forming component, A7: 0.0
(e) the remainder consists of one or more iron group metals as binder phase forming components and unavoidable impurities; and a hard phase: 50 to 95%, a binder phase: 5 to 50%, and the sintered hard alloy has a composition (volume %) consisting of: It is characterized by having a hardness distribution that decreases continuously and having a hard surface layer whose surface hardness is 5 to 30% higher than the internal hardness.

Next, referring to the sintered hard alloy of the present invention, the reason why the numerical values are limited as described above will be explained.

(a) Content of hard phase and binder phase If the content of the hard phase is less than 50% by volume, the content of the binder phase will be relatively higher than 50% by volume, which will affect the wear resistance and plasticity resistance of the alloy. On the other hand, if the content of the hard phase increases beyond 95% by volume, the content of the binder phase becomes relatively less than 5% by volume, and the toughness of the alloy decreases significantly. The content of the hard phase was determined to be 50 to 95% by volume, and the content of the binder phase was determined to be 5 to 50% by volume, respectively.

(b) Content of the hardened surface layer adjusting component and hardened surface layer forming component If the content of the hardening surface layer adjusting component is less than 10% by volume, the content of the hardened surface layer forming component will be relatively too high, exceeding 85% by volume; The thickness of the hardened surface layer becomes thicker than one rhyme,
The toughness of the alloy begins to deteriorate, and on the other hand, when the content of the hardened surface layer adjusting component exceeds 85.5% by volume, the content of the hardened surface layer forming component becomes relatively too small, less than 9.5%.
Since it would be difficult to form a hardened surface layer, the content of the hardened surface layer adjusting component was determined to be 10 to 85.5% by volume, and the content of the hardened surface layer forming component was determined to be 9.5 to 85% by volume.

(e) Content of Cr group metal If the content is less than 1% by volume, the desired effect of improving high-temperature strength and wettability with the hard phase cannot be secured, while if the content exceeds 15% by volume. If the content is 1 to 1, the toughness of the alloy will decrease.
It was set at 5% by volume.

(d) Content of AA If the content is less than 0.05% by volume, the desired high temperature strength cannot be obtained, while if the content exceeds 5% by volume, brittle phases such as NiTi (Al) will precipitate. As the toughness of the alloy decreases, its content is reduced to 0.0.
It was set at 5 to 5% by volume.

(e) Thickness of the hardened surface layer If the hardened surface layer is made thicker than 1 inch, its toughness will decrease, and if it is used as a cutting edge, it will be more likely to break, so the thickness should be set to l i7+! It was determined as follows.

(f) Surface hardness of the hardened surface layer If the hardness distribution is such that the degree of hardening of the surface hardness relative to the internal hardness of the alloy is less than 5%, the desired wear resistance and plastic deformation resistance cannot be imparted to the alloy. On the other hand, if the degree of hardening of the surface hardness is higher than 30% compared to the internal hardness of the alloy, when the alloy is used as a cutting edge, it will easily break. 5-30% compared to hardness
Set to high hardness.

Next, the sintered hard alloy of the present invention will be explained using examples.

Example 1 As raw material powders, TiC powder with an average particle size of 1.0 μm, TaC powder with an average particle size of 1.2 μm, WC powder with an average particle diameter of 1.2 μm, TiN powder with an average particle size of 1.5 μm, ZrN powder, 0.6 μm Mo powder, 1.0 μm W powder, 1.0 μm Ni powder, and 1.2 μm Co powder were used, and these raw material powders were as shown in Table 1. This mixed powder is pulverized and mixed in a ball mill, and then a green compact is press-molded from this mixed powder, and the green compact is heated to a temperature of 1250°C in a CO gas atmosphere of a pressure crab 1100 ml H. , followed by vacuum degree: 1σ21nr
The sintered hard alloys of the present invention (hereinafter referred to as the alloys of the present invention) 1 to 3, which have substantially the same composition as the blended composition, are obtained by sintering them at a temperature of 1450°C for 1 hour in a vacuum of ILHg (hereinafter referred to as the alloy of the present invention). , comparative sintered hard alloy (hereinafter referred to as comparative alloy)
1 and were manufactured, respectively.

Note that Comparative Alloy 1 has a content of hardening surface layer adjusting components that is outside the range of the present invention.

In addition, for the purpose of comparison, a green compact prepared by blending, mixing and press-molding the composition shown in Table 1 was prepared at a vacuum degree of 0.
Comparative alloy 2 without a hardened surface layer was produced by sintering at a temperature of 1450° C. for 1 hour in a vacuum of 5 mmHg.

Then, Cl5 (carbide Tool Association Standard)・SNMN43
Cutting test chips with shapes conforming to 2 were manufactured, and workpiece material: JIS-8NCM-8 (hardness HB: 270).
, Chip honing: 0.1mm.

Cutting speed: 200 m/mi! L.

Feed: 0.4mm1rev,, Depth of cut = 1.5 mm, Cutting time: 5. amin.

Continuous cutting tests were conducted under these conditions, and the maximum flank wear width of the test cutting edge was measured.

The results are shown in Table 2, which shows the average thickness and hardness distribution of the hardened surface layer, the internal hardness of the alloy, and the hardening ratio of the surface hardness to the internal hardness. Indicated.

Further, FIG. 1 shows the hardness distribution of Invention Alloy 1, Comparative Alloy 1, and Comparative Alloy 2.

As is clear from the results shown in Table 2 and FIG.
It was confirmed that both showed superior continuous cutting properties compared to Comparative Alloy 1.2 and Conventional Alloy 1, and had high wear resistance and plastic deformation resistance.

Example 2 As raw material powder, (Ti, Mo)CN powder (TiN) with an average particle size of 1.5 μm was used.
/Mo2C=20wt%/80wt%), average particle size 1.
5 μm (Ti, Nb)CN powder (TiN/NbC=
50% by weight (150% by weight), 1.2 μm WC powder and Co powder, 1.5 μm
ZrC powder and Fe powder, VC powder of 2.0 μm, MO@ powder of 0.6 μm, W powder, Cr powder, and Ni powder of 1.0 μm were used, and these raw material powders were The composition shown in the table was blended, and then a green compact was formed in the same manner as in Example 1.
and H2: heated to a temperature of 1250° C. under the flow of a mixed gas consisting of 1.01 J/mix, and then the vacuum degree was 10
Alloys 4 to 6 of the present invention having substantially the same composition as the blended composition were manufactured by sintering in a vacuum of -10-271L at a temperature of 1400°C for 1 hour.

For the purpose of comparison, Comparative Alloy 3 has a chemical composition defined in the present invention by changing the above sintering conditions, but the depth of the hardened surface layer is deep outside the range of the present invention, and Comparative Alloy 3 has a chemical composition that is similar to that specified in the present invention. Comparative alloy 4 was produced which was within the range of the present invention, but the hardening rate of the hardened surface layer exceeded the range of the present invention, followed by alloys 4 to 6 of the present invention, comparative alloys 3 and 4
, and cemented carbide P20 (hereinafter referred to as conventional alloy 2) without a hardened surface layer, which is conventionally known as a material for cutting tools.
A cutting test chip was manufactured under the same conditions as in Example 1. Work material: JIS-8NCM-8 (Hardness HB: 270) Chip honing: 0.03 mm.

Cutting speed: 150m/m Feed: 0.4mm/rev,,
Field 1 Depth of cut: 1.5mm.

Cutting time: iomiyt.

A continuous cutting test was conducted under the following conditions, and the maximum width of flank wear of the cutting edge was measured in the same manner as in Example 1.

The results are shown in Table 4 along with the appearance of the hardened surface layer.

Further, FIG. 2 shows the hardness distribution of Invention Alloy 4 and Comparative Alloy 34.

As shown in Table 4, the average thickness of the hardened surface layer and the hardening rate of alloys 4 to 6 of the present invention are outside the ranges defined by the present invention, resulting in chipping of the cutting edge and maximum wear on the flank surface. It is clear that this alloy has extremely superior cutting properties, that is, excellent wear resistance and plastic deformation resistance, compared to Comparative Alloys 3 and 4, for which width measurement was impossible, and the conventional alloy (P2O). It is.

Example 3 As a raw material powder, (Ti, W)CN powder (TiN/
WC=30 wt%/70 wt%), 1.2 μm WC powder, TaC powder, and C.

These raw material powders were blended into the composition shown in Table 5, pulverized and mixed in the same manner as in Example 1, and press-molded. Temperature 1250° in CH4 gas atmosphere of
Alloy 7 of the present invention, which has substantially the same composition as the blended composition, is obtained by heating the alloy to C and then sintering it by holding it at a temperature of 1400°C for 1 hour in a vacuum with a degree of vacuum of 10 mmHg. -9 and Comparative Alloy 5 were produced, respectively.

Note that Comparative Alloy 5 has a content of hardened surface layer forming components that is lower than the range of the present invention.

Next, chips for cutting tests were manufactured from the present invention alloys 7 to 9 and comparative alloy 5 under the same conditions as in Example 1. Work material: JIS-8NCM-8 (hardness HB: 270),
Chip honing: 0.03 mm, cutting speed: 1・OOm/miy't.

Feed: 0.6 mml rev,, Depth of cut: 1.5mm.

Cutting time: 10m1yt.

A continuous cutting test was conducted under the following conditions, and the maximum width of flank wear of the cutting edge was measured in the same manner as in Example 1.

The results are shown in Table 6 together with the appearance of the hardened surface layer.

As shown in Table 6, in Invention Alloys 7 to 9, the thickness and hardness of the hardened surface layer can be adjusted by the content of the hardened surface layer adjusting component, that is, the content of the hardened surface layer adjusting component decreases (this As the content of the hardened surface layer-forming components relatively increases with
It is clear that alloys 9 to 9 have significantly better wear resistance than comparative alloy 5.

Example 4 Raw material powders include Cr3C2 powder with an average particle size of 2.0 μm, MO2C powder with an average particle size of 1.5 μm, NbC powder with an average particle size of 1.6 μm, and (Ti, Ta)C powder (TiC/ TaC
=90 wt%/lO wt%), (Hf, Nb)C powder (HfC/Nb) with the same 1.2 μm
(Ti, Nb, W) C powder (T
iC/NbC/WC=30wt%/20wt%150
weight%).

2.2 μm VN powder, 1.5 μm HfN powder, 1.2 μm TaN powder, 1.0 μm (Ti, Nb)N powder (TiN/NbN)
-50% by weight, 150% by weight), 1.5 μm T1CN powder (TiC/TiN = 50% by weight, 150% by weight), 1.8 μm HfCN powder (HfC/HfN = 60% by weight/40% by weight), 2.0μm ■CN powder (VC/VN=70% by weight/
30% by weight), 2.0 μm (Ti, Ta)CN powder (TiC/Ta
N-70% by weight/30% by weight), (Zr, Nb, Ta)CN powder with an average particle size of 2.5 μm (
(Ti, Hf, Cr)CN powder (TiC
/TiN/HfN/Cr5C2=50wt%/20wt%/25wt%15wt%), 2.0 μm (Ti, V, W)CN powder (TiC/T
iN/VN/WC=40wt%/30wt%15wt%
/wt%/30 weight% (TiC/TiN/TaN/NbC/Mo2C=30wt%/30wt%/10wt%/10wt%/20wt%), Mo powder of 0.6μm, 1.0μm Prepare W powder, Cr powder, and Ni powder, 2.5 μm N1-A7 alloy powder (containing Al: 31% by weight), 1.2 μm Co powder, and 2.7 μm Fe powder, These raw material powders were blended into the composition shown in Table No. 7, pulverized and mixed in a ball mill, and press-molded into a green compact.
, H2: I It was heated to a temperature of 1250° C. under the flow of a mixed gas consisting of 7 mVt, and then the vacuum degree was 1 O-
21n7! Alloys 10 to 20 of the present invention having substantially the same composition as the blended composition were manufactured by holding and sintering the alloys at a predetermined temperature in the range of 1400 to 1450° C. for 1 hour in a vacuum of LHg.

Next, the average thickness and hardness distribution of the hardened surface layer of the alloys 10 to 20 of the present invention were measured under the same conditions as in Example 1, and the internal hardness of the alloy was also measured, and a continuous cutting test was conducted.

These results are shown in Table 7, and as shown in Table 7, the present invention alloys 10 to 20 have excellent wear resistance and plastic deformation resistance, and therefore have excellent cutting properties. It is clear that the performance is shown.

As mentioned above, the sintered hard alloy of the present invention has extremely excellent wear resistance, plastic deformation resistance, and toughness, so it can be used not only for general cutting but also for conventional cermet and WCC cemented carbide. It exhibits excellent cutting performance when applied to cutting relatively hard work materials, which have been weak, and heavy cutting with large loads, and has industrially useful properties such as being able to be used in the manufacture of wear-resistant parts. It is something that has.

[Brief explanation of drawings]

FIGS. 1 and 2 are curve diagrams showing the hardness distribution of the alloy of the present invention and the comparative alloy.

Claims (1)

[Scope of Claims] 1. Among the hard phase-forming components, one or more of the group consisting of carbides and composite carbides of metals of groups 4a, 5a and 6a of the periodic table: 1O to 85.5%; 4a and 5 of the periodic table as hard phase forming components.
One or more of the group consisting of nitrides, composite nitrides, carbonitrides, and composite carbonitrides of group a metals, and composite carbonitrides of group 4a and 5a metals and group 6a metals. : 9.5 to 85%, and the remainder consists of one or more iron group metals as binder phase forming components and unavoidable impurities, and hard phase: 50 to 95%. A sintered hard alloy having a composition (volume %) consisting of a binder phase of 5 to 50%, and further, the sintered hard alloy has a binder phase of 5 to 50%. 1. A sintered hard alloy having a hardened surface layer, which has a hardness distribution and has a hard surface layer whose surface hardness is 5 to 30% higher than the internal hardness. 2. 4a of the periodic table as a hard phase forming component. 1 [or 2 or more of the group consisting of carbides and composite carbides of group 5a and 6a metals: 10 to 85.5%
, 43 and 5 of the periodic table are also hard phase forming components.
One or more of the group consisting of nitrides, composite nitrides, carbonitrides, and composite carbonitrides of group a metals, and composite carbonitrides of group 4a and 5a metals and group 6a metals. : 9.5 to 85%, one or more Cr group metals = 1 to 15% as a binder phase forming component, and the remainder is an iron group metal as a binder phase forming component. A sintered hard alloy consisting of one or more types and unavoidable impurities, and having a composition (volume %) consisting of: hard phase: 50 to 95%, binder phase: 5 to 50%, and further) , The sintered hard alloy has a maximum depth of 11 rLm from its surface.
A sintered hard alloy having a hardened surface layer, which has a hardness distribution that continuously decreases toward the inside, and has a hard surface layer whose surface hardness is 5 to 30% higher than the internal hardness. . 3 4a of the periodic table as a hard phase forming component. One or more of the group consisting of carbides and composite carbides of group 5a and 6a metals: 10 to 85.5%
, 43 and 5 of the periodic table are also hard phase forming components.
One or more of the group consisting of nitrides, composite nitrides, carbonitrides, and composite carbonitrides of group a metals, and composite carbonitrides of group 4a and 5a metals and group 6a metals. =9.5 to 85%, as a binder phase forming component, l:0.
05-5%, the remainder consists of one or more iron group metals as binder phase forming components and unavoidable impurities, and hard phase: 50-95%, binder phase: 5-5%. 50%, and furthermore, the sintered hard alloy has a hardness distribution that continuously decreases inward from the surface to a maximum depth of 1. 1. A sintered hard alloy having a hardened surface layer, characterized in that the hardened surface layer has a surface hardness that is 5 to 30% higher than the internal hardness. 4 4a of the periodic table as a hard phase forming component. One or more of the group consisting of carbides and composite carbides of group 5a and 6a metals = 10 to 85.5%
, Also as hard phase forming components, 4a and 5 of the periodic table
One or more of the group consisting of nitrides, composite nitrides, carbonitrides, and composite carbonitrides of group a metals, and composite carbonitrides of group 4a and 5a metals and group 6a metals. = 9.5 to 85%, one or more Cr group metals = 1 to 15% as a bonding phase forming component, and A7: 0.05 to 5%% as a bonding phase forming component. and the remainder consists of one or more iron group metals as binder phase forming components and unavoidable impurities, and a composition consisting of: hard phase: 50 to 95%, binder phase: 5 to 50% ( The sintered hard alloy has a hardness distribution that decreases continuously from the surface to a maximum depth of 1 mm from the surface to the inside, and further has an internal hardness. A sintered hard alloy having a hardened surface layer characterized by having a hard surface layer having a surface hardness 5 to 30% higher than that of the hardened surface layer.