EP1249510A2 - Process for preparing tool steel articles by powder metallurgy - Google Patents

Abstract

Production of thick deformed or non-deformed objects made from tool steel comprises pouring a melt into a metallurgical vessel; conditioning to improve the degree of purity; adjusting the temperature to a value above the formation temperature of primary precipitation in the alloy; forming a powder having an average grain size of 50-70 mu m from the melt at constant temperature by injection nitrogen; disintegrating in the nitrogen stream; grading the powder; collecting, mixing and pouring into a container and compacting by hot isostatic pressing. The parameters of the pressing cycle are adjusted so that the temperature and pressure in the heating process are elevated.

Description

The invention relates to a method for powder metallurgical production of tool steel objects with improved homogeneity, higher Purity and improved properties.

Furthermore, the invention relates to a tool steel object improved property profile.

Tool steels with high carbon concentrations and high contents carbide-forming elements are used for cutting parts and components with high Wear resistance used. Because now when such alloys solidify in molds inhomogeneities as well as rough primary and eutectic carbides are formed, the manufacturing problems and poor mechanical properties of the tools or components created from it is one powder metallurgical production of such parts advantageous.

A powder metallurgical production essentially involves atomizing one Tool steel melt to metal powder, an introduction and compression of the Metal powder in a container or capsule, closing the capsule and heating and hot isostatic pressing of the powder in the capsule into one dense homogeneous material.

When the melt atomizes, which is advantageous according to the prior art done with nitrogen, small metal droplets with a high ratio of Surface to volume formed in the gas stream, which is a great cooling and Solidification rate of the liquid metal and therefore small carbide particles in the powder grains. As mentioned before, this will be discussed in the following Powder compacted by tapping in the capsule by hot isostatic Pressing at temperatures mostly above 1080 ° C with a pressure of greater formed as 85 MPa into a completely dense metal body. This as-HIPed Metal body, which can still be subjected to hot working, shows high carbide content an advantageously small carbide size of 1-3 on average um and good mechanical material properties compared to a metallurgical manufacturing.

Objects made of tool steel made by powder metallurgy possess a very advantageous structure with finely divided carbide phases; one incomplete material isotropy and a poor degree of purity However, the achievable high quality potential of PM materials has not been realized become.

Here, the invention seeks to remedy this and aims to remedy the lack of quality Articles made of PM tool steel according to the prior art to eliminate and to specify a method of the type mentioned above with which is an isostatically pressed metal body with the highest material isotropy and lowest content of oxidic inclusions can be produced.

The invention further aims at a tool steel object with improved Processing and usage properties with increased service life.

This goal is achieved in a generic method in that a Melt is introduced into a metallurgical vessel and conditioned in it, this is an improvement in the oxide purity of the same and an adjustment the temperature to a value above the formation temperature of Primary excretions in the alloy, after which at essentially constant held temperature from this melt by atomization with nitrogen Powder made with an average grain diameter of 50 to 70 microns, in Nitrogen stream disintegrated and while maintaining the nitrogen atmosphere classifies the powder with a maximum grain diameter of 500 µm, collected, mixed, in a container with a diameter or a thickness of greater than 300 mm and a length of greater than 1000 mm, by mechanical impacts are compressed in this and the container is sealed gas-tight is what then in a hot isostatic press cycle for this the parameters such can be set so that the temperature and pressure increase during the warm-up process be, all-round in the powder body of the container or capsule Pressure of at least 1 to 40 MPa is effective, and then an isostatic Pressing process at a temperature of at least 1100 ° C, but at most 1180 ° C, at an isostatic pressure of at least 90 MPa during one Period of at least three hours and then the HIP pressed body cooled and, if necessary, this pressed body subsequently warm formed and such a material with a DIN 50 602 K0 value of im essentially at most 3 is produced.

The advantages achieved with the method according to the invention are essentially is based on the fact that synergetically initially through metallurgical work on one in one metallurgical vessel introduced melt their oxidic purity significantly improved and their temperature homogeneous to an advantageous Overheating value can be set, after which atomization of the liquid metal is carried out in such a way that the mean grain diameter is 50 to 70 μm. This will achieved that the oxygen content in the powder is surprisingly low and on the other hand also the fine grain fraction essential with a view to achieving it a high knock and vibration density in the capsule is increased. If so, how provided according to the invention, the metal powder while maintaining the Nitrogen atmosphere classified, collected, placed in a container, in this compressed and the container is closed, no oxidation or Oxygen physisorption occurs on the powder grain surface.

An inventive distribution of the grain diameter with an average in The range of 50 to 70 µm enables an unexpectedly high one to be reached Powder density in the capsule, so that on the one hand its shrinkage when hot isostatic presses is low and on the other hand largely complete Isotropy of the pressed dense metal body is present. These benefits too for container sizes with a diameter or a thickness of more than 300 mm and a length of more than 1000 mm.

The parameters for the hot isostatic press cycle include warming up the Powder in the container with substantially the same increase in temperature and Pressure, which has already been shown to increase the Material density and homogeneity can be achieved. The subsequent pressing process takes place in the temperature range from 1100 ° C to 1180 ° C at a pressure of 90 MPa and larger with a duration of at least three hours, followed by one slow cooling of the compact. Press temperatures lower than 1100 ° C and pressures below 90 MPa and press times less than three hours Impact in the material

After the HIP, the pressed body has a completely dense material structure, can be turned into a tool in this condition or after hot forming are processed.

For the high quality of the process according to the invention Powder-metallurgically manufactured tool steel object is its low inclusion content and characteristic of the small inclusion size. The high degree of oxide purity, which with a K0 value according to DIN 50 602 of im essentially 3 is documented, not only leads to greatly improved mechanical properties, especially at elevated operating temperatures, the Material in all directions. but also improves it Performance characteristics, preferably the edge retention of Fine-cutting tools, to a large extent.

A particularly striking increase in the quality of the article is achieved in its manufacture by the process according to the invention if the melt is composed of an iron-based alloy and contains% by weight. Carbon (C) 0.52 to 3.74 Manganese (Mn) to 2.9 Chrome (Cr) to 21.0 Molybdenum (Mo) to 10.0 Nickel (Ni) if necessary to 1.0 Cobalt (Co) to 20.8 Vanadium (V) to 14.9 Niobium (Nb) tantalum (Ta) individually or in total to 2.0 Tungsten (W) to 20.0 Sulfur (S) to 0.5 and accompanying elements up to a total concentration of 4.8 and impurities and iron as the rest.
The above chemical composition of the tool steel contains particularly carbide-rich tool steels with high abrasion resistance and high cutting edge retention of the tools made from them. Since high carbide fractions generally impair the mechanical properties of the material, their fundamental improvement by the process according to the invention is of particular importance. It has been shown that these high mechanical characteristics, in particular that of the impact strength of the material, are synergistically due to the small mean grain diameter of the powder, a homogeneous dense filling of the same in the capsule and the high oxidic purity with an isotropic structure of the hot isostatically pressed object ,

The oxidic degree of purity of the liquid metal can be determined by a metallurgical Work can be effectively improved if the melt is conditioned in the metallurgical vessel with an induced turbulent flow of the same and when the metal bath is completely covered by liquid slag, which is heated in particular by means of direct current passage for a period of time of at least 15 minutes. A levy of Oxygen compounds or oxides from the melt and an uptake the same is conveyed into the hot slag, the induced flow of the Metal bath increases efficiency. A flow of is known per se Liquid metal in a metallurgical vessel by introducing argon purge gas by at least one gas-permeable sink arranged at the bottom to reach. However, it is important to prevent reoxidation of the melt that their coverage by liquid slag even with melt movements remains completely intact. To problems with the use of a sink with regard on the reliability of training a controlled and efficient Metal flow and difficulties in the flushing or stirring gas supply, wherein small amounts of gas show little metallurgical effect, but high amounts of gas Create and oxidize surface parts of the melt without slag and To avoid slag particles mixing into the steel, it is preferred electromagnetic means, for example electromagnetic stirring coils, for one Induce turbulent flow in the liquid metal. Maximum Setting and even distribution of the Temperature of the metal bath by introducing thermal energy into the Slag done through electrical current passage.

In a further embodiment of the invention it is provided that the conditioned Melt through a nozzle body in the metallurgical vessel with a Melt flow diameter from 4.0 to 10.0 mm in a spray chamber introduced and in this with at least three successive nitrogen with a purity of at least 99.999% nitrogen, formed gas jets with subject to the proviso that the last application of the Melt stream is carried out by a gas jet Has speed that is greater than the speed of sound. A Compliance with the melt flow diameter and the high kinetic energy of the Gas loading of the metal stream causes a favorable grain distribution and a desired fineness of the metal powder created. The conditioning and the Setting the temperature of the liquid metal in the metallurgical vessel as well the high purity of the atomizing gas nitrogen is also the cause for a surprisingly high degree of purity or a low oxygen content of the powder and as a result of the hot isostatically pressed block.

Because even small amounts of coarse grain in the metal powder, especially when filling capsule and when compacting the powder in it, cause segregation can be advantageous if the diameter of the powder grains in terms of atomization, set or classified to a maximum value of 500 µm becomes.

At most, it can be used to ensure a homogeneous filling and Quality increase of the product according to the invention provided that the in powder collected in a staging area fluidized by nitrogen and mixed and in a container or while maintaining the nitrogen atmosphere introduced a capsule with a total weight of more than 0.5 t mechanical impacts are compressed and sealed gas-tight.

In this way it can be ensured that if the homogenized powder in a container or capsule with a diameter or a thickness of 400 mm or more and a length of at least 1000 mm is introduced, using the aforementioned parameters for the hot isostatic press cycle, the block produced homogeneity and perfect Material density achieved.

When the powder-filled capsule is cold in a HIP facility is introduced and a subsequent heating of the powder capsule under All-round ambient pressure, the soaking time can on the one hand Shortened due to increased heat conduction and the powder mass in view pre-compressed to a largely complete isotropy of the block.

It has been shown, in certain cases, to support the Consolidation be favorable if the heating and / or the pressing process of the Powder at constant, possibly evenly changing, by one Average oscillating temperature exposure is carried out and the Pressing process at a temperature of at least 1140 ° C, but at most of 1170 ° C.

Because of the improved material properties, it is possible and it can be particularly advantageous for minimizing costs if the invention powder-metallurgically produced block in the as-HIPed state or at the lowest for economic reasons to be carried out as primary material for Tools or tool parts are used.

The further object of the invention to create a tool steel object with improved machining and usage properties with increased service life is achieved in a powder-metallurgically manufactured object made of tool steel with improved material properties consisting of an iron-based alloy containing% by weight. Carbon (C) 0.52 to 3.74 Manganese (Mn) to 2.9 Chrome (Ce) to 21.0 Molybdenum (Mo) to 10.0 Nickel (Ni) if necessary to 1.0 Cobalt (Co) to 20.8 Vanadium (V) to 14.9 Niobium (Nb) tantalum (Ta) individually or in total to 2.0 Tungsten (W) to 20.0 Sulfur (S) to 0.5 as well as accompanying elements up to a total concentration of 4.8 and impurities and iron as the remainder, which material according to DIN 50 602 has a K0-W of at most 3.

Tool steels have a wide range of concentration of each Alloy elements, whereby these always interact and with regard can be seen on the carbon content. Carbon levels less than 0.52 % By weight lead to a low carbide content and / or to a low one Matrix hardness in the heat-treated condition of the steel, whereas higher Content as 3.74 wt .-% carbon, even in a powder metallurgical Manufacturing, the material for use as a tool due to the largely exclude mechanical property profile.

Of particular importance for good hardenability and the achievable Mechanical and chemical properties of the objects are the elements Mn and Cr, with contents of over 2% by weight Mn and over 21% by weight Cr Cause a drop in the material values required for the tools.

The high affinity for carbon of the elements Mo, V, Nb / Ta and W results in the desired proportions in a desired carbide and mixed carbide formation in an alloy matrix. In the order of the elements above, however, the concentration values in% by weight should be 10.0; 14.9; 2.0; 20.0 must not be exceeded because, on the one hand, this means that the desired remuneration behavior and, on the other hand, the manufacturability and the intended mechanical properties of the materials cannot be achieved.
Ni can optionally be present in the alloy up to a content of 1.0% by weight without any adverse effect
Co increases the hot hardness and cutting edge stability of the tools, but has a property-worsening effect from a content of 20.8% by weight. Sulfur contents of up to 0.5% by weight improve the machinability of the tool steel without, however, adversely affecting the degree of purity thereof. that the mechanical material values are reduced.

According to the invention, the tool steel has one defined according to DIN 50 602 K0 value of essentially at most 3. This high degree of purity of the Material not only brings about a great improvement in mechanical Properties in the tempered state, for example a significantly increased Toughness of the material, but it's also the usage properties, especially the edge retention of fine-cut tools for hard Objects raised suddenly. This increase in quality of the invention Items made of tool steel made by powder metallurgy is as found was justified in particular by the fact that the small proportion of smaller and Lack of larger non-metallic inclusions one caused by them Crack initiation minimized.

Von Kaltarbeitsstählen und Schnellarbeitsstählen mit Kohlenstoffgehalten C von größer als 2,2 Gew.-%, ca 12,5 Gew.-% Cr und über 4,0 Gew.-% V bzw. 1,1 bis 1,4 Gew.-% C, ca 4,3 Gew.-% Cr, ca 5 Gew.-% Mo, 3 bis 5 Gew.-% V, 5,8 bis 6,5 Gew.-% W, gegebenenfalls bis 9 Gew.-% Co Rest jeweils Eisen und Verunreinigungen wurden zur Erprobung 50 Stück 8 t Chargen geschmolzen, in ein mit einer Verdüsungskammer verbundenes metallurgisches Gefäß eingebracht, mit reaktiver Schlacke abgedeckt und diese mittels Elektroden bei direktem Stromdurchgang beheizt. In einem Zeitraum von 15 bis 45 Minuten erfolgte ein Konditionieren der Schmelze bei einem induktiven turbulenten Rühren derselben, wobei der Schmelzenspiegel immer mit heißer Schlacke abgedeckt war. Danach wurde eine Bohrung in einem Düsenkörper des metallurgischen Gefäßes freigesetzt und ein in die Verdüsungskammer eintretender Schmelzenstrom mit einem Durchmesser von 4,0 bis 10,0 mm mittels aufeinanderfolgenden Stickstoff-Gasstrahlen beaufschlagt, wobei der letzte Gasstrahl mit Überschallgeschwindigkeit aus der Düse austrat, auf das Flüssigmetall gerichtet war und dieses in Tröpfchen zerteilte. In der Verdüsungskammer erfolgte eine Erstarrung der Tröpfchen zu Pulverkörnern in Stickstoff mit einem Reinheitsgrad von 99,999 %. Die Stickstoffatmosphäre über dem Pulver wurde auch bei einem Klassieren und Sammeln desselben aufrechterhalten, wobei aus dem Sammelbehälter jeweils Proben zur Klassierung der Pulverpartikel gezogen wurden.

The invention is explained in more detail below on the basis of test results:

Of cold-work steels and high-speed steels with carbon contents C of greater than 2.2 wt.%, Approx. 12.5 wt.% Cr and over 4.0 wt.% V or 1.1 to 1.4 wt.% C, approx. 4.3 wt.% Cr, approx. 5 wt.% Mo, 3 to 5 wt.% V, 5.8 to 6.5 wt.% W, optionally up to 9 wt.% Co The rest of the iron and impurities were melted for testing, 50 pieces of 8 t batches, placed in a metallurgical vessel connected to a atomization chamber, covered with reactive slag and heated by means of electrodes with direct current passage. The melt was conditioned over a period of 15 to 45 minutes with inductive turbulent stirring, the melt level always being covered with hot slag. A bore was then released in a nozzle body of the metallurgical vessel and a melt stream with a diameter of 4.0 to 10.0 mm, which entered the atomization chamber, was acted upon by successive nitrogen gas jets, the last gas jet exiting the nozzle at supersonic speed, onto which Liquid metal was directed and divided it into droplets. The droplets solidified in the atomization chamber to form powder granules in nitrogen with a purity of 99.999%. The nitrogen atmosphere above the powder was also maintained when it was classified and collected, with samples for classifying the powder particles being taken from the collection container.

The powder was introduced from the collecting container into a container or a capsule made of unalloyed steel, whereby by shaking or tapping the same or a compression of the powder filling and subsequently one Closing the capsule were made. The one with condensed Alloy powder filled capsule with a diameter of 420 mm⊘ and one Length of 2000 mm was introduced into the HIP system when cold, after which the pressure and temperature were increased at the same time. On hot isostatic pressing was carried out at a temperature of 1155 ° C. Pressure of 105 MPa in a period of 3.85 hours, after which the compact was slowly cooled. After hot forming with 0.2 times to 8.1 times the degree of deformation was removed from the forgings of samples.

The 50 powder samples taken from the collecting container when using the method according to the invention were subjected to a sieve analysis. The results, namely the respective average powder content in the individual particle classes, are shown in Table 1 (particle size distribution of the metal powder) in comparison with 92 results when using methods according to the prior art. Grain distribution of the metal powder, proportion of the particle classes in the metal powder, average particle size Particle class micron Process according to the invention Share in% State of the art comparison procedure Share in% 0-45 31.5 12.7 46-63 20.5 9.0 64-75 8.7 5.3 76-100 11.0 9.2 101-125 7.6 9.8 126-180 9.5 14.0 181-250 6.0 13.2 251-355 3.7 12.8 355-500 1.5 14.0 Medium particle size 61μm 141μm

Powders made by a method according to the invention had until to a grain diameter of 63 to account for 52% of the total and a share of approx. 72% up to a grain size of up to 100 µm. Powder according to the prior art, however, have proportions of for the same classes 21.7% and 36.2%. If one compares the determined average particle size, it is this in the case of powder production according to the invention is 61 μm, whereas in one Powder production according to the state of the art is more than twice as large average particle size of 141 µm was determined.

In Fig. 1 (manufacturing method according to the invention) and Fig. 2 (manufacturing method according to the prior art) powders are shown in bulk. At a such a bed, as shown in FIG. 2, in the comparison powder (state of the Technology) segregation areas with an accumulation of coarse powder grains 1 and fine fractions 2. On the other hand, the powder produced according to the invention largely homogeneous. The same applies to Fig. 3 (powder production according to of the invention) and Fig. 4 (comparison powder) according to the prior art.

From the 50 blanks, each with a different chemical composition, produced by the method according to the invention, samples were taken after hot forming and their degree of purity or content of non-metallic inclusions according to DIN 50 602 and ASTM E 45/85 Meth.D was examined. These results were again compared with the results of 92 samples made of the same type of material, but produced according to the state of the art, and are compared in Table 2 (inclusion content of PM tool steels K0) and Table 4 (inclusion content of PM tool steels according to ASTM value) , Inclusion content of PM tool steels K0 (DIN 50 602) Tool steel according to the invention Tool steel according to the state of the art K0 Number of samples Proportion of % Number of samples Proportion of % 0 28 56.0 15 16.3 1 18 36.0 28 30.4 2 3 6.0 19 20.7 3 1 2.0 12 13.0 4 7 7.6 5 2 2.2 6 3 3.3 7 1 1.1 8th 9 10 11 12 1 1.1 13 1 1.1 14 1 1.1 15 1 1.1 16 17 18 1 1.1 19 20 total 50 100 92 100

When evaluating the inclusion content in the material according to DIN 50 602 Method K0 were used for tool steels according to the invention Total sum parameters up to a maximum of 3 with a share of this value of 2% determined. In contrast, as can be seen from Table 2, tool steels, created according to the state of the art, a much higher content non-metallic inclusions with a comparatively large diameter. A The results of this evaluation are shown graphically in FIG. 5. where the sum parameters on the abscissa and their share in ordinate % are plotted. Therefore curve A shows the material according to the invention and curve B is a steel made according to the prior art.

Another study of the content of non-metallic inclusions in Tool steels manufactured using powder metallurgy were produced in accordance with ASTM E 45/85 Meth.D.

As can be seen from Table 3, a maximum ASTM value of 1.5 was determined on 50 samples of material produced according to the invention (curve A) with a number of samples 3 and a proportion of 6.0%. With an ASTM value of 0.5, the proportion was 68%. The comparative material, manufactured according to the prior art, had a higher content and coarser inclusions (curve B), which is also shown graphically in FIG. 6, the ASTM value again being plotted on the abscissa and the percentage on the ordinate , Inclusion content of PM tool steels (ASTM E 45/85 Meth. D) Tool steel acc. invention Tool steel acc. State of the art ASTM values Number of samples Proportion of % Number of samples Proportion of % 0.5 34 68.0 24 26.1 1.0 13 26.0 35 38.0 1.5 3 6.0 22 23.9 2.0 6 6.5 2.5 4 4.4 3.0 1 1.1 total 50 100 92 100

Tool steels of the type described can, as from the investigation Was surprisingly found, according to the invention, up to a content of 0.5 % By weight be alloyed with sulfur without the content of non-metallic Inclusions is significantly increased and a DIN K0 value of greater than 3 established.

Claims (15)

Process for the powder metallurgical production of dense, deformed or non-deformed objects made of tool steel with improved homogeneity, higher purity and improved properties of the material, one The melt is introduced into a metallurgical vessel and conditioned in it this is an improvement in the oxide purity of the same and an adjustment the temperature to a value above the formation temperature of Primary excretions in the alloy, after which at essentially constant held temperature from this melt by atomization with nitrogen Powder made with an average grain diameter of 50 to 70 microns, in Nitrogen stream disintegrated and while maintaining the nitrogen atmosphere classifies the powder with a maximum grain diameter of 500 µm, collected, mixed, in a container with a diameter or a thickness of greater than 300 mm and a length of greater than 1000 mm, by mechanical impacts are compressed in this and the container is sealed gas-tight is what then in a hot isostatic press cycle for this the parameters such can be set so that the temperature and pressure increase during the warm-up process be, all-round in the powder body of the container or capsule Pressure of at least 1 to 40 MPa is effective, and then an isostatic Pressing process at a temperature of at least 1100 ° C, but at most 1180 ° C, at an isostatic pressure of at least 90 MPa during one Period of at least three hours and then the HIP pressed body cooled and, if necessary, this pressed body subsequently warm formed and thus a high-purity material with a value according to DIN 50 602-K0 of essentially at most 3. The method of claim 1, wherein the iron-based alloy melt contains by weight. Carbon (C) 0.52 to 3.74 Manganese (Mn) to 2.9 Chrome (Cr) to 21.0 Molybdenum (Mo) to 10.0 Nickel (Ni) if necessary to 1.0 Cobalt (Co) to 20.8 Vanadium (V) to 14.9 Niobium (Nb) tantalum (Ta) individually or in total to 2.0 Tungsten (W) to 20.0 Sulfur (S) to 0.5 and accompanying elements up to a total concentration of 4.8 and impurities and iron as the rest. The method of claim 1 or 2, wherein conditioning the Melt in the metallurgical vessel with an induced turbulent flow the same, preferably by electromagnetic means, and at one complete covering of the metal bath by liquid slag, which is heated in particular by direct current passage for a period of time of at least 15 minutes The method of claims 1 to 3, wherein the conditioned melt is through a nozzle body in the metallurgical vessel with a Melt flow diameter from 4.0 to 10.0 mm in a spray chamber introduced and in this with at least three successive nitrogen with a purity of at least 99,999% nitrogen, formed gas jets with subject to the proviso that the last application of the Melt flow takes place through a gas jet, which at least in places Has speed that is greater than the speed of sound. Method according to one of claims 1 to 4, wherein the diameter of the Powdered grains are set to a maximum value of 500 µm by atomization technology or is classified. Method according to one of claims 1 to 5, wherein the in one Staging area collected powder fluidized and mixed by nitrogen and while maintaining the nitrogen atmosphere in a container or capsule brought in with a total weight of more than 0.5 t, by mechanical shocks compressed and sealed gas-tight. Method according to one of claims 1 to 6, wherein the powder in a Container or a capsule with a diameter or a thickness equal to or greater than 400 mm and a length of at least 1500 mm. Method according to one of claims 1 to 7, wherein the powder-filled Cold capsule is placed in a HIP device and a Subsequent heating of the powder capsule under all-round ambient pressure he follows. A method according to any one of claims 1 to 8, in which the heating and / or the pressing process of the powder at constant, if necessary evenly changing, swinging around an average Temperature application is carried out and the pressing process at a Temperature of at least 1140 ° C, but not more than 1170 ° C. Method according to one of claims 1 to 9, wherein the powder-metallurgically produced block in the AS HIPed state or at the lowest for economic reasons to be carried out as primary material for Tools or tool parts are used. Powder-metallurgically manufactured object made of tool steel with improved material properties, preferably manufactured by a method according to the preceding claims, consisting of an iron-based alloy containing% by weight Carbon (C) 0.52 to 3.74 Manganese (Mn) to 2.9 Chrome (Cr) to 21.0 Molybdenum (Mo) to 10.0 Nickel (Ni) if necessary to 1.0 Cobalt (Co) to 20.8 Vanadium (V) to 14.9 Niobium (Nb) / tantalum (Ta) individually or in total to 2.0 Tungsten (W) to 20.0 Sulfur (S) to 0.5 and accompanying elements up to a total concentration of 4.8 and impurities and iron as the remainder, which high-purity material according to DIN 50 602 has a K0 value of at most 3 or according to ASTM E 45/85 Meth.D an ASTM value of at most 1.5 , Powder metallurgical article according to claim 11, formed from a Material which has an inclusion content - according to DIN 50 602 method K0- for the Sum of characteristic values 1 and 0 has a share of more than 80%. Powder metallurgical article according to claim 11, formed from a Material with an inclusion content - according to DIN 50 602 method K0- for the Characteristic value 0 has a share of more than 50%. Powder metallurgical article according to claim 11, formed from a Material with an inclusion content - according to ASTM E 45/85 Meth. D- for the Sum of the ASTM values 0.5 and 1 has a share of greater than 90%. Powder metallurgical article according to claim 11, formed from a Material which has an inclusion content according to ASTM E 45/85 Meth. D for ASTM value of 0.5 has a share of greater than 60%.

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