EP2195473A1

EP2195473A1 - Tool

Info

Publication number: EP2195473A1
Application number: EP08758755A
Authority: EP
Inventors: Benno Gries; Leo Prakash
Original assignee: HC Starck GmbH
Current assignee: HC Starck GmbH
Priority date: 2007-10-02
Filing date: 2008-05-26
Publication date: 2010-06-16
Also published as: DE102007047312A1; US20100239855A1; CN101809203A; WO2009046777A1; WO2009046777A8; KR20100074140A

Abstract

The invention relates to a coated metal cutting tool with reduced adhesion wear and increased thermal resistance.

Description

description

Tool

Technical area

The present invention relates to a coated

Metal cutting tool with reduced adhesion wear and increased heat resistance, in particular a hard metal tool for machining of alloys such as steels, cast iron, stainless steels and non-ferrous base alloys, such as superalloys.

State of the art

Carbide tools for metal cutting are composites and consist of at least two phases, one of which is the metallic binder phase, and one or more the hard material phase (s). As hard materials are in particular carbides, nitrides and carbonitrides of refractory metals such as tungsten, molybdenum, titanium, zirconium, hafnium, chromium, vanadium, niobium and tantalum in question. The binder phase generally consists of cobalt and, depending on the carbon activity during sintering, contains fractions of such refractory metals whose free formation enthalphes are low enough to partially decompose into the metallic form during sintering, in particular W, Cr and Mo.

In addition to cobalt, the binder phase can also contain Fe and Ni ₁ or even Fe and Ni and no cobalt. Such binding systems show advantages in the field of toxicology, since they have less contact corrosion with carbides than with pure cobalt. For reasons of better availability of Fe and Ni, there has been no shortage of attempts in the past to introduce FeCoNi or FeNi-based binding systems in carbide metal cutting tools, which has hitherto not been technically successful, unlike other hard metal applications.

The binder phase encloses in the sintered state, the hard material phase, which can have a determined by optical or electron-optical methods size between 10 and 0.05 microns after sintering - depending on Zerspanungsaufgabe. This size is mainly adjusted by the fineness of the hard powder used. Cutting tools have a defined geometry, whose task is, for example, to use the tool in a cutting tool receiving the cutting forces frictionally to create the chip and deliberately break, and dissipate the resulting heat as possible with the expiring Span. So-called indexable inserts have a basic geometry derived from a cuboid or a plate, often with a hole in the middle, and one or more cutting edges with a purposefully produced fillet. Other cutting tools, such as for cutting, are self-retaining thanks to their geometry and have only one cutting edge. Often, the surface also has knobs or reliefs to minimize the contact surface of the chip with the cutting tool. The selection of the correct geometry is of enormous importance for the tool life, the surface quality after machining and the safety of the chip breakage.

The dissertation Preikschat (Karlsruhe University of Technology 1994 and KfK 3550, ISSN 0303-4003) describes machining trials with uncoated carbide tools with FeCoNi binders on cast iron GG30. The service life of the tools was determined by strong adhesive wear and the resulting high cutting forces, a binder system with martensitic structure due to the higher binder strength shows less wear than a comparable tool, which had a purely cubic face-centered grid (austenite) as a binder phase. However, the life curve of the austenitic binder - starting from a lower level - was flatter than that of the martensitic binder, i. cheaper at high cutting speeds. Both binder systems were clearly inferior to pure cobalt as the binder phase for the carbide tools used because of the adhesive wear.

In addition to adhesive wear also plays the hot strength for the life of Zerspanungswerkzeugen an important role. The cutting edge, which engages the chips by shearing, heats up very much and is under strong mechanical Thrust load. Both in combination lead to plastic creep and lowering of the cutting edge, if the high temperature creep resistance is not sufficient for the given application. In particular, turning operations in continuous operation with high feeds, high-strength alloys and dry machining are critical, although the tool can not cool sufficiently. Since the determination of the hot or creep resistance is very expensive, the hot hardness is measured as a guide practically, and sometimes their time dependence. As is generally known from the field of metallurgy, the hot hardness of Fe, Co or Ni base alloys can be increased by alloying the elements of subgroup 6a of the periodic table. In carbide production with cobalt as a binder, it is possible by controlling the carbon potential during sintering to alloy up to about 6 mol% tungsten to the binder, which leads to carbide tools with outstanding heat resistance or hot hardness. In FeCoNi-based binder systems with low cobalt contents, and more particularly FeNi-based, as the cobalt content decreases, less and less tungsten dissolves, so that the hot strengths of these binder alloys are generally insufficient for machining. At 1250 ^° C., the solubility of WC in Fe, Co or Ni is 7, 22 and 12 percent by weight, respectively, which additionally depends on the carbon supply. Therefore, it is believed by those skilled in the art that decreasing cobalt content is expected to result in decreasing hot hardness, and thus increasingly less suitable as a binder phase for carbide tools for metal cutting. Since the cost of the binder phase increases with increasing cobalt content, and also the health risk due to corresponding grinding dust during finishing, there is an interest in reducing the cobalt content of the binder phase as much as possible in the production of metal cutting tools. While hard metals with pure Fe and pure Co binder have a good course of the hot hardness, those with pure Ni binder are greatly inferior. The reason is the high ductility of the nickel. The dissertation Prakash (Leo J. Prakash, University of Karlsruhe 1979,

Faculty of Mechanical Engineering, KfK 2984) describes that an increase in the hot hardness of WC-based cemented carbides with FeCoNi binders is possible by alloying Cr and / or Mo. The hot hardness up to about 600 ⁰ C is predominantly determined by the high temperature properties of the binder, above it is determined by the structure of the hard material skeleton resulting from the used hard material powders. But individual binding alloys based on FeCoNi with cobalt contents lower than 40% achieved without alloying with other elements quite heat curing, which are similar to those of pure cobalt binder from 400 to 800 ⁰ C equal or even superior to, for example, FeCoNi 70/15/15, 65 / 20/15 and 25/25/50 or 50/25/25, despite the lower bond densities compared to cobalt and thus higher binder contents in the cemented carbide. Therefore, such binder alloys are in principle suitable to withstand the stresses on the cutting edge as well as cobalt, or even clearly superior in the case of the latter alloy.

Noteworthy is the behavior of the two austenitic binder phases FeCoNi 25/25/50 and 50/25/25 with respect to the course of hardness as a function of the temperature: although the initial level of hardness at room temperature is comparatively low, is at 800 ⁰ C found a value which is even higher than that of cobalt as a binder phase. The waste is monotonous and uniform, while cobalt and especially the hard metals with martensitic binder phases have an unsteady course. The cause could be the temperature-related, increasing transformation of martensite into austenite, which destabilizes the structure and facilitates creeping processes, thus reducing the measured hot hardness. However, the dissertation Preikschat clearly shows that an austenitic binder phase has less resistance to adhesive wear because of its lower strength. Thus, advantages in the hot hardness or creep resistance can not be brought to bear. In addition to the already mentioned additional elements such as Cr and Mo, Re and Ru are also suitable for increasing the heat resistance, and the carbon content of high Fe-containing binder alloys on Fe ₁ Co, Ni-base also increases the thermal hardness. Naturally, a sintered hard metal with both pure Co and FeCoNi or FeNi binder always also contains dissolved carbon and / or tungsten. The content of these elements must be tailored, which is done by mastering the carbon balance in batch preparation and sintering, and by measuring the density and magnetic properties of the sinter, often by measuring the carbon content. If the carbon content is too high or too low, harmful so-called "eta-phases" or carbon precipitations are formed which are classified according to ISO 4505. Both are very disadvantageous.Carbide with high hot hardness is preferably treated with a high tungsten content. The solubility limits of other elements such as Cr and Mo in the binder metal phase are determined for a given carbon supply by the presence of eta phase above the solubility limits.

When carbide tools with intermittent engagement, as happens when interrupted rotation or milling, also plays the thermal shock resistance a role. This size depends on physical parameters such as coefficient of expansion, thermal conductivity and tensile strength at high temperatures. Lack of thermal shock resistance manifests itself in so-called comb cracks on the cutting edge.

Brief description of the invention

The invention relates to carbide tools, in particular

Indexable inserts or other cutting tools with the following features:

A carbide tool with a geometry suitable for metal cutting, a coating suitable for metal cutting, at least one hard material phase and a single- or multi-phase Binder phase, characterized in that the proportion of the elements iron (Fe), cobalt (Co) and nickel (Ni) in the total amount of these elements in the binder phase for Co between 0 and 40 wt .-%, preferably from 5 to 40 wt. %, Fe between 20 and 90 wt .-% and for Ni between 5 and 75 wt .-%, wherein the proportions add up to 100%.

2. Hard metal tool according to item 1, characterized in that the binder phase is alloyed as a result of sintering with tungsten to a content that neither eta phases nor carbon precipitations are included.

3. carbide tool according to item 1 or 2, characterized in that the binder phase is alloyed to the maximum extent as a result of sintering with Cr and / or Mo, that no eta-phase occurs.

4. A cemented carbide tool according to one or more of items 1 to 3, wherein the cobalt content is less than 5%, and is alloyed with molybdenum at most to the solubility limit, wherein the molybdenum content is generated by introducing its metal, nitride or oxide.

5. A cemented carbide tool according to one or more of the items 1 to 4, wherein the binder phase contains one, two or three phases in the mixture selected from austenitic phase, martensitic phase and tetragonal distorted martensitic phase.

6. A cemented carbide tool according to one or more of the items 1 to 5, wherein the binder phase additionally contains 5 to 30 wt .-% chromium and the sum of the percentages of the metals Co, Ni, Cr and Fe is less than or equal to 100 wt .-%.

7. carbide tool according to one or more of the items 1 to 6, wherein the binder phase additionally contains up to 5 percent by mass V, Mo and / or Al and / or Ti ₁ W, Ta / Nb, Zr and / or Hf in each case in one part less than or equal to the solubility limit of the respective substance and / or up to 15 mass% Mn.

8. A cemented carbide tool according to one or more of the items 1 to 7, wherein the binder phase additionally contains oxygen, nitrogen and / or boron in the proportion of their maximum solubility or less. 9. A cemented carbide tool according to one or more of items 1 to 8, wherein the content of carbon in the binder phase is set so that no precipitates of unbound carbon are present.

10. Hard metal tool according to one or more of the items 1 to 9, wherein the coating comprises or consists of at least one refractory metal nitride, boron nitride, diamond, oxide, sulfides or mixtures thereof.

11. The cemented carbide tool according to one or more of items 1 to 10, wherein the coating comprises or consists of titanium nitride, titanium aluminum nitride TiAIN, TiCN, aluminum oxide, TiTaNbC, tungsten carbon or mixtures thereof.

12. Hard metal tool according to one or more of the items 1 to 11, wherein the coating has at least two layers, preferably with different layer thicknesses and / or coating materials.

13. carbide tool according to one or more of the points 1 to

12, wherein the coating has a layer sequence TiN / TiCN / Al ₂ O ₃ / TiN or TiN / TiCN / Al ₂ O ₃ / TiN.

14. carbide tool according to one or more of the points 1 to

13, wherein the thickness of the coating is between 0.5 μm and 100 μm, preferably between 1 μm and 50 μm, advantageously between 2 μm and 20 μm, in particular 3 μm and 10 μm

15. carbide tool according to one or more of the points 1 to

14, wherein the mean grain size of the hard material phase is between 0.1 and 10 μm, preferably between 0.2 and 7 μm, in particular between 0.3 and 4 μm or 0.5 to 4 μm or 1 to 3 μm.

16. Hard metal tool according to one or more of the points 1 to

15, wherein the binder phase contains no hexagonal portions.

17. carbide tool according to one or more of the points 1 to

16, wherein the hard material phase carbides, nitrides and / or carbonitrides, preferably the refractory metals, and / or mixtures thereof. 18. Hard metal tool according to one or more of the items 1 to 17, wherein the hard material phase tungsten carbide or their mixed crystals.

19. Hard metal tool according to item 18, wherein additionally at least one further cubic carbide phase or mixed carbide phase is contained and the proportion of cubic carbide phase can be up to 30% by weight.

20. A method for producing a cemented carbide tool according to one or more of items 1 to 19, comprising the steps of: providing a binder metal powder of the composition according to one or more of the preceding claims; Providing a hard material powder; - mixing hard material and binder metal powder to obtain a first mixture; Pressing the first mixture into a blank; -Sintering the blank to sintering -if possibly mechanical post-processing of the sintering-applying the coating according to one or more of the preceding claims.

21. A method for producing a carbide tool according to item 20, wherein the hard material powder has an average particle size of 0.3 to 10 .mu.m, preferably 0.5 to 7 .mu.m, in particular 1 to 4 microns.

22. A method for producing a hard metal tool according to item 20 or 21, wherein the hard material has a BET surface area of 0.1 m ² / g to 8 rτv7g, advantageously from 0.2 nfVg to 6 m ² / g or 0.1 m ² / g to 4 m ² / g, in particular from 0.25 nfVg to 4.5 nfVg, or from 0.3 m ² / g to 4 m ² / g or 5 m ² / g.

23. A method for producing a cemented carbide tool according to one or more of the items 20 to 22, wherein the hard material is tungsten carbide, tungsten carbide or a mixture of these substances.

24. Use of a carbide tool according to one or more of the items 1 to 19 for the machining of metal workpieces or non-metal workpieces.

25. Use of a cutting material according to item 24 for the machining of chromium-containing metal workpieces, characterized in that the proportion of chromium in the binder phase of the cutting material is not greater than the chromium content in the steel alloy of the workpiece.

26. Use according to item 24 or 25, wherein the metal workpiece is a workpiece made of steels, cast iron, stainless steels and non-ferrous base alloys such as superalloys, aluminum, brass, titanium, or plastics, fiber composites. Detailed Description of the Invention Now, what is desired is a cemented carbide tool for machining of

Metal alloys, wherein the cobalt content of the binder is as low as possible. In summary, it can be said that in the

Prior art cemented carbide tools are the major cause of failure, too strong adhesion and lack of heat resistance. Therefore, it has not been known that on the basis of existing solutions actually usable carbide tools for machining of corresponding metal workpieces were combined.

It was therefore an object of the present invention to provide an operational carbide cutting tool, which has a reduced adhesive wear and increased heat resistance, so that it can be used as a carbide tool for machining of alloys such as steels, cast iron, stainless steels and non-ferrous base alloys, like superalloys, is suitable.

This object is achieved by the cemented carbide tool according to the present invention. The hard metal tool according to the invention therefore has the following features: 1) a coating, [0019] and [0020] 2) a) an austenitic at room temperature at least proportionally

FeCoNi-based binder phase with 5 to 40% Co, 90 to 20% Fe, Ni min. 5% to max. 75% (regardless of the other components of the Binders the sum is always to be expected 100%), in addition also W and / or C as a result of sintering as a binder for cemented carbides, possibly also Cr and / or Mo when using corresponding carbide, nitride or metal powders containing

3) a geometry which is suitable for the machining of metallic materials and mounting in a tool holder.

The claimed range for cobalt is a compromise between the rising above 40% inhalation toxicity of the powdery binder alloy in contact with WC on the one hand, and the decreasing cobalt content solubility of tungsten in the binder on the other. Below 5% cobalt, the tungsten solubility becomes too small to have to be replaced by the more soluble molybdenum, but this does not take the form of carbide molybdenum compounds, which undesirably mix carbides with e.g. Can form tungsten carbide and thus are not effective in the binder, but in the form of metallic or decomposing during sintering nitrides, so that metallic molybdenum dissolves immediately in the binder and thus the increase in the heat resistance of the binder is fully available.

Above 5% cobalt, this mechanism can also be used, but is not absolutely necessary.

Hard metal tool according to the present invention have a defined geometry, whose task is, for example, to force fit the tool in a cutting forces receiving tool holder, create the chip and selectively break, and the resulting heat as possible with the expiring span dissipate. Suitable are conventional geometries of so-called indexable inserts. These often have a basic geometry derived from a cuboid or plate, often with a hole in the middle, and one or more cutting edges with a purposefully made fillet, such as four-hexagonal or octagonal platelets. Other cutting tools, such as for cutting, are self-retaining thanks to their geometry and have only one cutting edge. Often the surface indicates also nubs or reliefs to minimize the contact surface of the chip with the cutting tool.

The binder alloy may be both austenitic (face-centered cubic) and martensitic (body-centered cubic, possibly distorted tetragonal) as well as the mentioned two or three phases contained in the mixture. However, a high proportion of austenite is preferred because of the good thermal behavior of the temperature, which can be adjusted by the ratio of the components Fe, Co and Ni in the binder phase.

More specifically, the hard metal tool consists of a hard metal or cermet cutting material for machining metal workpieces (such as steels, cast irons, stainless steels, and nonferrous base alloys such as superalloys) with a hard material phase containing carbides, nitrides, and / or carbonitrides Binder phase of iron, cobalt and nickel, which contains 5 to 40% cobalt, 90-20% iron and 5 to 75% nickel, wherein the proportions add up to 100%, and a coating.

The amount of binder phase present in the cemented carbide tool is from 3 to 40% by weight, advantageously from 5 to 20% by weight, and the hard material phase, both phases being complementary to 100% by weight. In addition, for example, diamond, intermetallic phases or an oxide reinforcement may be present.

The invention further relates to the use of the hard metal tool for the machining machining of metal workpieces.

In cemented carbides, such as in cermets, the binder serves to form a liquid phase at sintering temperature which can be in equilibrium with and wet the hard material phase. The liquid binder phase should have a considerable solubility for the hard material phase with the sintering temperature, but should excrete it on cooling again. Furthermore, the binder phase should have mechanical properties which correspond to the intended use and the prevailing temperatures in such a way that the binder for a hard and tough as possible cohesion of the hard metal or cermet body leads. In machining operations such as turning, milling or drilling steel grades, especially austenitic steels, a gluing of the hard metal or cermet cutting material with the steel workpiece is often noted despite suitable geometry, which is due to the resulting increased wear of the cutting tool and the poor quality machining on the workpiece is undesirable.

This problem is also solved with the present invention, since the coating shows an advantageous effect here.

According to the invention, the binder phase has 0 mass% to 40 mass% Co, 5 mass% to 75 mass% Ni, 20 mass% to 90 mass% Fe. In a further embodiment of the invention may also contain 5 mass% to 30 mass% Cr, wherein the sum of the metals Co, Ni, Cr and Fe does not exceed 100%. In cobalt-free binder metals, cobalt can occur as an inevitable impurity. Thus, the binder phase may additionally contain up to 5 mass% V, Mo and / or Al, up to the solubility limit Ti, W, Ta / Nb, Zr and / or Hf and up to 15 mass% Mn. Furthermore, oxygen, nitrogen and / or boron can be present in the binder to the maximum solubility. The content of carbon in the cutting material is adjusted so that at best traces of eta phases and no precipitations of unbound carbon are present. Preferably, the binder phase has no hexagonal proportions.

The binder phase in the tool according to the invention is obtained by using a binder metal powder having the desired composition for producing the tool. The binder metal powder used to make the tool can be obtained by conventional methods such as mixing the elemental powders of the metals in the binder metal powder or by atomizing a molten alloy of the desired composition. Particularly suitable for this purpose are prealloyed powders which can be obtained in the desired composition by precipitation of metal salt solutions in suitable precipitants and subsequent reduction, as for example in WO 97/21844, US Pat. No. 5,102,454, US Pat. No. 5,912,399, WO 00/23 631, EP1079950 described. Likewise, such pre-alloyed alloy powders may be used in admixture with elemental powders as binder metal powder, as described in WO2008 / 034903.

Although the mechanisms of reactions and interactions between the metals and carbon contained in the steel are very complex, it has surprisingly been found in the machining of metal workpieces that excellent results could be obtained when the tool is coated.

As the hard material phase, it is possible to use generally known carbides, nitrides and / or carbonitrides, preferably those of the refractory metals, and mixtures thereof and mixed crystals with cubic carbides, for example TiTaNbC. Tungsten carbide is particularly advantageous here. The hard material phase is generally used in the form of powders. The average particle sizes (according to ASTM-B-330, FSSS) of the hard powder used are usually about 0.3 μm to 10 μm, advantageously 0.4 μm to 7 μm or 0.5 μm to 4 μm. The hard material powders used have BET surface areas of generally less than 0.1 m ² / g to 4 m ² / g.

But it can also hard material powder with BET surface areas of 0.1 m ² / g to 8 m ² / g, advantageously from 0.2 m ² / g to 6 m ² / g, in particular from 0.25 rτv7g to 4.5 m ² / g, or from 0.3 m ² / g to 4 m ² / g or 5 rτv7g be used.

It is also possible to use a mixture of different powder qualities, e.g. a tungsten carbide powder having a mean grain size of 1 μm mixed with a tungsten carbide powder having a mean grain size of 5 μm.

In a further embodiment of the invention, a mixture of tungsten carbide (WC) and tungsten carbide (W2C) is used as the hard material phase. The mixture can be present as a powder mixture or as a mixture of both substances within the powder particles.

But it can also hard material powder, in particular tungsten carbide, with BET surface areas of 1 nfVg to 8 m ² / g, advantageously from 2 m ² / g to 6 m ² / g, in particular from 2.5 m ² / g to 4.5 m ² / g, or from 3 nrVg to 4 m ² / g or 5 m ² / g. The coating consists of a refractory metal nitride, boron nitride,

Diamond, oxides, sulfides or mixtures thereof. Particularly suitable titanium nitride TiN, titanium aluminum nitride TiAIN ₁ TiCN, TiAISiN, TiTaNbC ₁ MoS2, or mixtures thereof. Also, some metastable or amorphous coatings are suitable, such as TiAIN or tungsten / carbon.

Furthermore, multilayer coatings are also possible which contain different layer thicknesses and coating materials. Possible layer sequences are e.g. For example, TiN / TiCN / AbOa / TiN, TiN / TiCN / AbOs / TiN. Usual thicknesses of the coating are between a few microns and several 100 microns. The total thickness of the coatings is usually from 1 .mu.m to 50 .mu.m, advantageously from 2 .mu.m to 20 .mu.m and in particular from 3 .mu.m to 10 .mu.m.

These coatings are applied by CVD ("chemical vapor deposition"), PVD ("physical vapor deposition") or related methods.

If appropriate, the cemented carbide substrate is modified superficially or near the surface in the composition before application of the coating by sintering or subsequent treatments in such a way that the layer adhesion is optimal.

The coating is generally adapted very specifically to the material to be machined and to the hard metal. Preferably, the coating is under compressive stress; Tensile stresses often cause tearing and flaking.

The cemented carbide tools according to the invention find use for machining metal workpieces or non-metal workpieces.

These may be, for example, chromium-containing metal workpieces, wherein the proportion of chromium in the binder phase of the cutting material, ie the material from which the hard metal tool according to the invention consists, is not greater than the chromium content in the steel alloy of the workpiece. In addition, it may be a workpiece made of steels, cast iron,

Stainless steels and non-ferrous base alloys such as superalloys, aluminum, brass or titanium act. Non-metallic materials may also be processed, such as fiber composites or thermoplastic or thermosetting plastics, which may also be reinforced with fibers such as glass or carbon fibers, fillers or other reinforcing agents, such as glass fibers. Nanocomposites.

The present invention also relates to a method for producing a cemented carbide tool according to one or more of the preceding claims, comprising the steps:

Providing a binder metal powder of the composition according to the invention;

- Providing a hard material powder;

- mixing hard material and binder metal powder to obtain a first mixture;

- Pressing the first mixture to a blank;

- Sintering of the blank to a sintering

Optionally mechanical post-processing of the sintered product

- Applying the coating according to the invention.

Suitable binder metal powders and hard powder powders are described above. In a particular embodiment of the invention, the binder metal powder may be provided by preparing a pre-alloyed metal powder of the desired composition described in WO 97/21844, US 5,102,454, US 5,912,399, WO 00/23 631, EP1079950, to which reference is made. In a further embodiment of the invention, the binding metal powder can be provided by mixing a prealloyed metal powder with one or more elemental powders, ie metal powders which consist only of a metal as described in WO2008 / 034903, to which reference is made.

The hard material powder advantageously has a mean particle size of 0.3 to 10 .mu.m, preferably 0.5 to 7 .mu.m, in particular 1 to 4 microns. The hard material powder has a BET surface area of 0.1 m ² / g to 8 m ² / g, advantageously from 0.2 m ² / g to 6 m ² / g or 0.1 m ² / g to 4 m ² / g, in particular from 0.25 m ² / g to 4.5 m ² / g, or from 0.3 m ² / g to 4 m ² / g or 5 m ² / g. As hard material tungsten carbide, tungsten carbide or a mixture of these substances can be used advantageously.

The mixing can advantageously by a common

Wet grinding, for example in a suspension, be effected.

The first mixture may also contain pressing or sintering aids, such as waxes, long-chain carboxylic acids, their esters or salts, or polymers such as polyethylene glycol or polyacrylates.

The compression to a blank is usually designed as uniaxial pressing and generally carried out at pressures of 50-250 MPa.

The sintering takes place usually at temperatures of about 1200 ⁰ C to 1600 ⁰ C, in particular 1250 ⁰ C to 1550 ⁰ C in an inert atmosphere or in vacuo instead.

Examples

Example 1)

A hard metal powder mixture consisting of 94 wt.% WC with a

Grain size of 0.8 micron (ASTM B330) and a binder content of 6 wt%, in turn consisting of 70Fe12Co18Ni, was produced by wet milling in an attritor and processed into granules in a conventional spray dryer. The carbon content of the mixture was adjusted so that the cemented carbide does not contain any harmful third phases such as free carbon or carbon deficit phases ("eta phases") after sintering Hard metal carbide inserts with a geometry according to CNMG120408 were made by axial dry pressing a compression was produced and then vacuum sintered in a graphite sintering furnace for one hour at 1450 ^° C. The metallographic examination of the carbide semi-finished products showed that the cemented carbide had a uniform microstructure with a WC particle size of about 0.6 microns good and very few coarse grains of coarse grains up to a grain size of 3 microns were seen was 1920 kg / mm ² (Vickers hardness at 10 kg load, "HV10") The X-ray examination showed that the binder consists mainly of martensite and some retained austenite.

The hard metal insert blanks were ground to size, the

Rounding cutting edges and then provided with an industry-standard PVD coating based on TiAIN. Standstill tests were carried out when turning without coolant insert at a cutting speed of 250 m / min, feed 0.3 mm / rev, cutting depth 2 mm in a 42CrMo4 low-alloy steel.

Comparative Example 1): The service life of a conventional WC-Co cemented carbide of the same geometry, the same coating and the same composition, but purely cobalt-bound, was 5 minutes in comparison, while with the WC-70Fe12Co18Ni cemented carbide in Example 1 a service life of 6 Minutes under the same cutting conditions. The criterion for the end of service life was a wear mark width ("VBmax.") Of 0.2 mm.

Example 2)

A hard metal powder mixture consisting of 94 wt.% WC with a

Grain size of 0.8 microns and a binder content of 6 wt% consisting of 50Fe25Co25 Ni was produced as conventional and described above. The hardness of the sintered hard metals was 1850 kg / mm 2 (HV10). The microstructure was very even without WC coarse grains> 2 microns. The binder was pure austenitic. The sintered insert blanks CNMG 120408 were ground to size and a part with a commercial PVD coating based on TiAIN with a layer thickness of about 5 microns. Another part of the inserts was provided with a typical CVD coating based on TiN / TiCN / Al 2 O 3 / TiN with a total layer thickness of 8 microns. These PVD or CVD coated inserts were tested in a tool life trial when turning 42CrMo4 steel at a cutting speed of 220 m / min in a CNC controlled machining center. Comparative Example 2): The WC-Co

Reversible inserts of the same composition exhibited a life of 6 minutes in uncoated form with the WC-50Fe25Co25Ni PVD coated insert showing a life of 8.5 minutes and the CVD coated insert with the same substrate exhibiting a life of 8.0 minutes. Criterion for the end of life was a wear mark width VBmax of 0.2 mm. The lower service life of the WC-Co insert was due to a higher plastic deformation of the cutting edge and a correspondingly poorer surface finish of the workpiece.

Example 3)

A hard metal powder mixture consisting of 83.5 wt.% WC with a particle size of 1, 1 .mu.m, a mixed carbide consisting of TiTaNbC of 8% and a binder content of 8.5 wt% consisting of 70Fe12Co18Ni present as mixed crystal was prepared by wet milling in produced an attritor and processed into granules in a conventional spray dryer. The carbon content of the mixture was adjusted so that the cemented carbide does not contain any harmful third phases such as free carbon or etaphases after sintering. Were produced and the type CNMG120408 by dry pressing followed by sintering for one hour under vacuum in a graphite sintering furnace at 1480 ⁰ C carbide inserts. These were then heat treated to produce a mixed-crystal-poor zone of about 25 microns in thickness. Metallographic examination of the cemented carbide substrate revealed that the cemented carbide had a uniform microstructure with a WC grain size of approximately 1.2 microns and a solid-solution grain size of 1 micron. The binder distribution was uniform. The hardness of the cemented carbide was 1600HV10 and the X-ray examination showed that the binder consists mainly of martensite and some retained austenite.

The hard metal insert blanks were ground to size, the cutting edges rounded and then provided with a conventional CVD multilayer coating based on TiN / TiCN / Al2O3 / TiN with a total layer thickness of 8 microns. Standstill tests were when turning without coolant insert with a cutting speed of 200 m / min, feed 0.32 mm / rev, cutting depth 2 mm in a 42CrMo4 low alloy steel.

Comparison Example 3): The service life of the conventional cemented carbide WCTiCTaC-Co (type P20 / P25) was 10 minutes in the same composition, geometry and coating, with the WC-TiC-TaC-70Fe12Co18Ni cemented carbide a service life of 12 Minutes achieved under the same cutting conditions. Criterion for the end of life was a wear mark width VBmax of 0.2 mm.

The conventional cobalt-bonded cemented carbide tool showed a pronounced plastic deformation of the cutting edge at the end of its life, while the FeCoNi-bonded cemented carbide tool showed only a few crevice and flank wear. The coating showed signs of wear but was still intact. There were no signs of adhesive wear.

Claims

claims

1. carbide tool with a geometry suitable for metal cutting, suitable for metal cutting coating, at least one hard material phase and a single- or multi-phase binder phase, characterized in that the proportion of elements iron (Fe), cobalt (Co) and nickel (Ni) the total amount of these elements in the binder phase for Co is between 0 and 40% by weight, advantageously from 5 to 40% by weight, for Fe between 20 and 90% by weight and for Ni between 5 and 75% by weight , where the proportions add up to 100%.

2. Hard metal tool according to claim 1 or 2, characterized in that the binder phase is alloyed to the maximum extent as a result of sintering with Cr and / or Mo, that no eta-phase occurs.

3. A cemented carbide tool according to one or more of the preceding claims, wherein the cobalt content is less than 5%, and is alloyed with molybdenum at most up to the solubility limit, wherein the molybdenum content is generated by introducing its metal, nitride or oxide.

4. A cemented carbide tool according to one or more of the preceding claims, wherein the binder phase additionally contains 5 to 30 wt .-% chromium and the sum of the percentages of the metals Co, Ni, Cr and Fe is less than or equal to 100 wt .-%.

5. carbide tool according to one or more of the preceding claims, wherein the binder phase additionally contains up to 5 percent by mass V, Mo and / or Al and / or Ti, W, Wa / Nb, Zr and / or Hf in each case a smaller or smaller equal to the solubility limit of the corresponding substance and / or up to 15 mass% Mn.

A cemented carbide tool according to one or more of the preceding claims, wherein the proportion of carbon in the binder phase is adjusted so that no precipitates of unbound carbon are present.

7. carbide tool according to one or more of the preceding claims, wherein the coating titanium nitride. Titanium Aluminum Nitride TiAIN. TiCN. Alumina, TiTaNbC, tungsten carbon or mixtures thereof, or consists thereof.

8. Hard metal tool according to one or more of the preceding claims, wherein the coating has at least two layers, preferably with different layer thicknesses and / or coating materials.

9. carbide tool according to one or more of the preceding claims, wherein the coating has a layer sequence TiN / TiCN / Al2O3 / TΪN or TiN / TiCN / Al2O3 / TΪN.

10. Hard metal tool according to one or more of the preceding claims, wherein the thickness of the coating between 0.5 .mu.m and 100 .mu.m, preferably between 1 .mu.m and 50 .mu.m, advantageously between 2 .mu.m and 20 .mu.m, in particular 3 .mu.m and 10 .mu.m

11. carbide tool according to one or more of the preceding claims, wherein the mean grain size of the hard material phase between 0.1 and 10 .mu.m, preferably between 0.2 and 7 .mu.m, in particular between 0.3 and 4 microns or 0.5 to 4 microns or 1 to 3 microns.

12. Hard metal tool according to one or more of the preceding claims, wherein the hard material phase carbides, nitrides and / or carbonitrides, preferably of the refractory metals, and / or mixtures thereof and preferably contains up to 30 wt .-% of one or more cubic carbide phases.

A method of manufacturing a cemented carbide tool according to one or more of the preceding claims, comprising the steps of: providing a binder metal powder of the composition according to one or more of the preceding claims; Providing a hard material powder; - mixing hard material and binder metal powder to obtain a first mixture; Pressing the first mixture into a blank; Sintering of the blank to sintering -if possibly mechanical post-processing of the sintering-applying the coating according to one or more of the preceding claims.

14. A method for producing a carbide tool according to one or more of the preceding claims, wherein the hard material powder has an average particle size of 0.3 to 10 microns, preferably 0.5 to 7 microns. in particular 1 to

4 microns.

15. Use of a carbide tool according to one or more of the preceding claims for machining metal workpieces or non-metal workpieces.

16. Use according to claim 24 or 25, wherein the metal workpiece is a workpiece of steels, cast iron, stainless steels and non-ferrous base alloys such as superalloys, aluminum, brass, titanium, or plastics, fiber composites.