EP1250205B1 - Method for producing angular, stainless shot-blasting abrasives based on an fe-cr-c alloy - Google Patents

Method for producing angular, stainless shot-blasting abrasives based on an fe-cr-c alloy Download PDF

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EP1250205B1
EP1250205B1 EP01942587A EP01942587A EP1250205B1 EP 1250205 B1 EP1250205 B1 EP 1250205B1 EP 01942587 A EP01942587 A EP 01942587A EP 01942587 A EP01942587 A EP 01942587A EP 1250205 B1 EP1250205 B1 EP 1250205B1
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Prior art keywords
alloy
process according
gas mixture
stainless
chromium
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German (de)
French (fr)
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EP1250205A1 (en
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Reinhard SÄNGER
Oliver Zyto
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Vulkan Inox GmbH
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Vulkan Strahltechnik GmbH
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/36—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.7% by weight of carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/14—Treatment of metallic powder
    • B22F1/142—Thermal or thermo-mechanical treatment
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
    • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
    • C22C33/0285—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with Cr, Co, or Ni having a minimum content higher than 5%
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/76—Adjusting the composition of the atmosphere
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr

Definitions

  • the invention relates to a method for producing abrasive grains from stainless steel casting, in which a melt is first hardenable iron-chromium-carbon alloy a granulate is produced which then undergoes a heat treatment at> 900 ° Celsius for hardening and then broken into sharp-edged grains.
  • Two categories of blasting media made of stainless steel casting are known. These are, on the one hand, granules from spherical grains, which consist of steel materials of medium hardness ( ⁇ 45HR C ). As disclosed in JP 61 257 775, sharp-edged grains made of hardened chrome cast iron (> 60HR C ) are also used because they can achieve improved abrasive properties.
  • the Production of the sharp-edged, hardened granules Compared to the abrasive grains of the first category, the Production of the sharp-edged, hardened granules a much higher Manufacturing effort with additional process steps required.
  • the Production is according to JP 61 257 775 from a melt to a curable Chromium cast iron alloy starting from a granulate in essential round grains. This is hardened by following it a heat treatment is quenched in water at 1000 ° C to 1100 ° C. After that, the grains are broken, leaving a sharp-edged material arises.
  • the present invention is based on the object To provide processes for the production of stainless abrasive, at oxidation during and after the final heat treatment of the granules can be excluded and in which the by Hardening reached brittleness of the material is so high that breaking the Blasting grain to sharp-edged granules is possible with simple means.
  • this task solved in that the heat treatment in a reducing atmosphere follows and that only for the subsequent cooling reducing gas or gas mixture is used.
  • the reducing atmosphere is expediently a Gas mixture containing hydrogen and nitrogen.
  • Gas mixture is suitable, the 60% to 80% hydrogen and 20% to 40% nitrogen contains. The best results were achieved with 70% hydrogen and 30% Nitrogen.
  • a vibrating tube mill is particularly suitable, order the desired sharp-edged from the hardened starting material To produce granules.
  • the abrasive is classified according to the grain size.
  • a further process step for grain fractionation with which the setting of the desired grain mixture is achieved, can be connected downstream of the production method according to the invention.
  • the drawing shows a flow diagram of the manufacturing process, the the upper part comprises the process steps for producing the starting granulate, while the lower part shows hardening, breaking and classifying.
  • the starting material for the abrasive is steel scrap, which is the manufacturing process is fed from a scrap warehouse 1.
  • the desired Alloy is shaped into carbon from suitable storage containers of graphite 2 and chrome 3 added.
  • the raw material mixture is then in one Melting furnace 4 melted into an alloy. This contains 2.0% carbon and 30% to 32% chromium.
  • the melt passes through at a temperature of more than 1420 ° Celsius Spraying device 5, wherein a granulate with a wide range of Grain diameter arises.
  • the atomized droplets of the molten metal become quenched in a water bath so that solid granules settle to the bottom a granulation basin 6 accumulates.
  • Cooling 10 is the starting material for the rust-resistant Chrome cast alloy before.
  • the starting granulate is now fed to a furnace 11, in which it is annealed at more than 900 ° C. in an atmosphere of hydrogen and nitrogen 13 at low pressure and then cooled, after which it is conveyed into a storage container 12.
  • a furnace 11 By annealing the granulate at> 900 ° C, secondary carbides are separated from the alloy-rich matrix, which changes the composition of the matrix.
  • a martensite conversion is only possible through the separation of the secondary carbides, which then leads to an increase in hardness to> 60 HR C when the granules cool down from temperatures> 900 ° C.
  • the granulate is removed from the container 12 by means of a bucket elevator 14 Crushers 15 fed.
  • the crusher 15 is preferably a vibrating tube mill trained and crushed the hardened, brittle granules to sharp edges Failure bodies. The use of such pulse mills makes it possible especially good, the material under strong internal tension disassemble sharp-edged fragments. The one created when breaking Grain mix has a wide size distribution.
  • Now for classification pass through a screening plant 16.
  • the crusher becomes too coarse oversize 17 fed again.
  • the too fine undersize 18 becomes the process at this point removed and melted in the melting furnace 4.
  • Gutkom 19 with one Diameters between 0.1 and 0.8 mm are either stored in a silo 20 or abandoned for fine classification of another screening plant 21. Blasting media with different grain sizes are used in silos 22, 23 and 24 stocked until removed for shipment to the end user become.

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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Powder Metallurgy (AREA)
  • Polishing Bodies And Polishing Tools (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Heat Treatment Of Articles (AREA)
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  • Conductive Materials (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

The invention relates to a method for producing rust-resistant, angular shot-blasting abrasives (>60 HRC) based on a Fe-Cr-C alloy. According to said method, a granulate consisting of an iron-chrome-carbon alloy is tempered to >60 HRC by subjecting it to a thermal treatment of greater than 900° Celsius in a reduced atmosphere. A stainless, hard material which can be reduced to angular granules is thus produced. This results in shot-blasting abrasives with excellent characteristics for treating the surface of workpieces consisting of stainless material, e.g. stainless steel, non-ferrous metal and natural stone.

Description

Die Erfindung betrifft ein Verfahren zur Herstellung von Strahlmittel-Körnern aus nichtrostendem Edelstahlguß, bei dem zunächst aus der Schmelze einer härtbaren Eisen-Chrom-Kohlenstoff-Legierung ein Granulat erzeugt wird, welches dann eine Wärmebehandlung bei >900° Celsius zur Härtung durchläuft und anschließend zu scharfkantigen Körnern gebrochen wird.The invention relates to a method for producing abrasive grains from stainless steel casting, in which a melt is first hardenable iron-chromium-carbon alloy a granulate is produced which then undergoes a heat treatment at> 900 ° Celsius for hardening and then broken into sharp-edged grains.

Zur Strahlbehandlung von Werkstücken aus nichtrostenden Materialien ist es erforderlich, ebenfalls rostfreie Strahlmittel zu verwenden, weil rostende Strahlmittel, wie Stahlschrot oder Stahlkies, auf der Werkstückoberfläche eisenhaltige Rückstände hinterlassen. Durch die Oxidation der anhaftenden Eisenreste treten dann unerwünschterweise innerhalb kürzester Zeit Rostflecken auf. Neben nichtmetallischen, meist mineralischen Strahlmitteln, wie z. B. Elektrokorund, Siliziumkarbid oder Glas, sind auch nichtrostende metallische Strahlmittel bekannt. Zu nennen ist hierbei Edelstahlgußstrahlschrot aus rostbeständigen Stahllegierungen. Dieses Material hat gegenüber den mineralischen Strahlmitteln eine Reihe von Vorzügen. So läßt sich mit den metallischen Strahlkömern eine wesentlich erhöhte Standzeit in den üblichen Strahlanlagen erzielen, da der Edelstahl aufgrund seiner größeren Duktilität bei der Strahlbehandlung in wesentlich geringerem Ausmaß zertrümmert wird. Aufgrund des durch die hohe Schlagzähigkeit bedingten, guten Verschleißverhaltens hat sich insbesondere bei der Verwendung in Strahlanlagen, die mit Schleuderrädern ausgestattet sind, der Einsatz von Edelstahlstrahlmitteln bewährt. It is for the blasting treatment of workpieces made of rustproof materials also necessary to use rustproof blasting media, because rusting Abrasives, such as steel shot or steel gravel, on the workpiece surface leave ferrous residues. By the oxidation of the adherent Iron residues then occur undesirably within a very short time Rust stains. In addition to non-metallic, mostly mineral abrasives, such as z. As electrical corundum, silicon carbide or glass are also rustproof metallic abrasives known. Stainless steel shot blasting should be mentioned here made of rust-resistant steel alloys. This material has compared to the mineral abrasives have a number of advantages. So with the metallic grains have a significantly longer service life in the usual Shot blasting systems because the stainless steel due to its greater ductility the beam treatment is smashed to a much lesser extent. Because of the good impact due to the high impact strength Wear behavior has been particularly noticeable when used in Blasting systems equipped with centrifugal wheels, the use of Proven stainless steel abrasives.

Zwei Kategorien von Strahlmitteln aus nichtrostendem Edelstahlguß sind bekannt. Dies sind zum einen Granulate aus kugeligen Körnern, die aus Stahlwerkstoffen mittlerer Härte (<45HRC) bestehen. Wie in der JP 61 257 775 offenbart, werden zum anderen auch scharfkantige Körner aus gehärtetem Chromgußeisen (>60HRC) eingesetzt, da sich durch diese verbesserte abrasive Eigenschaften erzielen lassen.Two categories of blasting media made of stainless steel casting are known. These are, on the one hand, granules from spherical grains, which consist of steel materials of medium hardness (<45HR C ). As disclosed in JP 61 257 775, sharp-edged grains made of hardened chrome cast iron (> 60HR C ) are also used because they can achieve improved abrasive properties.

Gegenüber den Strahlmittelkörnem der ersten Kategorie wird bei der Herstellung des scharfkantigen, gehärteten Granulats ein wesentlich höherer Fertigungsaufwand mit zusätzlichen Prozeßschritten erforderlich. Bei der Herstellung wird nach der JP 61 257 775 von einer Schmelze einer härtbaren Chromgußeisenlegierung ausgehend zunächst ein Granulat aus im wesentlichen runden Kömern hergestellt. Dieses wird gehärtet, in dem es nach einer Wärmebehandlung bei 1000°C bis 1100°C in Wasser abgeschreckt wird. Danach werden die Körner gebrochen, so daß ein scharfkantiges Material entsteht.Compared to the abrasive grains of the first category, the Production of the sharp-edged, hardened granules a much higher Manufacturing effort with additional process steps required. In the Production is according to JP 61 257 775 from a melt to a curable Chromium cast iron alloy starting from a granulate in essential round grains. This is hardened by following it a heat treatment is quenched in water at 1000 ° C to 1100 ° C. After that, the grains are broken, leaving a sharp-edged material arises.

Nachteilig ist bei dieser Methode, daß durch das Abschrecken des mehr als 1000° Celsius heißen Stahls in Wasser die unerwünschte Oxidation des Materials begünstigt wird. Desweiteren ist bei der Verwendung von Wasser die erreichbare Abkühlrate stark eingeschränkt (Dampfphase). Effektives Abschrecken ist jedoch absolut notwendig, um ein möglichst sprödes Material zu erhalten. Dies ist die Voraussetzung dafür, daß die Körner später so gebrochen werden können, daß das gewünschte scharfkantige Granulat erzeugt wird.The disadvantage of this method is that the more than Steel in water is called 1000 ° Celsius the undesirable oxidation of the material is favored. Furthermore, when using water achievable cooling rate severely restricted (vapor phase). effective Quenching is, however, absolutely necessary to make the material as brittle as possible to obtain. This is the prerequisite for the grains to be like this later can be broken that produces the desired sharp-edged granules becomes.

Dementsprechend liegt der vorliegenden Erfindung die Aufgabe zugrunde, ein Verfahren zur Herstellung von nichtrostendem Strahlmittel bereitzustellen, bei dem während und nach der abschließenden Wärmebehandlung eine Oxidation des Granulates ausgeschlossen werden kann und bei dem die durch das Härten erreichte Sprödigkeit des Materials so hoch ist, daß ein Brechen des Strahlkorns zu scharfkantigem Granulat mit einfachen Mitteln möglich ist.Accordingly, the present invention is based on the object To provide processes for the production of stainless abrasive, at oxidation during and after the final heat treatment of the granules can be excluded and in which the by Hardening reached brittleness of the material is so high that breaking the Blasting grain to sharp-edged granules is possible with simple means.

Bei einem Herstellungsverfahren der eingangs genannten Art wird diese Aufgabe dadurch gelöst, daß die Wärmebehandlung in reduzierender Atmosphäre folgt und daß für die daran anschließende Abkühlung ausschließlich ein reduzierendes Gas oder Gasgemisch verwendet wird.In a manufacturing process of the type mentioned, this task solved in that the heat treatment in a reducing atmosphere follows and that only for the subsequent cooling reducing gas or gas mixture is used.

Dadurch daß das Granulat beim Härten ausschließlich einer reduzierenden Atmosphäre ausgesetzt ist, ergibt sich der Vorteil, daß eine unerwünschte Oxidation des Materials zuverlässig vermieden werden kann.Because the granules are only reducing during hardening Exposed to atmosphere, there is the advantage that an undesirable Oxidation of the material can be reliably avoided.

Zweckmäßigerweise handelt es sich bei der reduzierenden Atmosphäre um ein Gasgemisch, das Wasserstoff und Stickstoff enthält. In der Praxis hat sich gezeigt, daß sich für das erfindungsgemäße Verfahren insbesondere ein Gasgemisch eignet, das 60% bis 80% Wasserstoff und 20% bis 40% Stickstoff enthält. Die besten Ergebnisse wurden erzielt mit 70% Wasserstoff und 30% Stickstoff.The reducing atmosphere is expediently a Gas mixture containing hydrogen and nitrogen. In practice it has shown that in particular for the inventive method Gas mixture is suitable, the 60% to 80% hydrogen and 20% to 40% nitrogen contains. The best results were achieved with 70% hydrogen and 30% Nitrogen.

Um Strahlmittel einer Eisen-Chromguß-Legierung herzustellen, sind besondere Verfahrensschritte einzuhalten. Durch die Verwendung einer Eisen-Chrom-Kohleinstoff-Legierung mit mindestens 2% Kohlenstoff und wenigstens 30% Chrom ergibt sich ein Material, welches korrosionsbeständig härtbar ist, wobei sich Härten von > 60 HRC ohne weiteres erzielen lassen. So ergibt sich ein Material, das sich durch eine hohe Widerstandfähigkeit gegen Oxidation und durch einen hervorragenden Verschleißwiderstand auszeichnet. Die Verwendung der bezeichneten Legierung bei dem erfindungsgemäßen Verfahren ist also besonders zweckmäßig, da hiermit die Kombination eines gut härtbaren und gleichzeitig korrosionsbeständigen Werkstoffes gegeben ist.In order to produce blasting media from an iron-chromium casting alloy, special process steps must be followed. The use of an iron-chromium-carbon material alloy with at least 2% carbon and at least 30% chromium results in a material which can be hardened in a corrosion-resistant manner, with hardnesses of> 60 HR C being readily achievable. This results in a material that is characterized by its high resistance to oxidation and by excellent wear resistance. The use of the specified alloy in the method according to the invention is therefore particularly expedient, since this provides a combination of a material which is well hardenable and at the same time corrosion-resistant.

Für das Brechen des gehärteten Granulates ist es zweckmäßig, eine Impulsmühle zu verwenden. Insbesondere eine Rohrschwingmühle ist gut geeignet, um aus dem gehärteten Ausgangsmaterial das gewünschte scharfkantige Granulat zu erzeugen.It is advisable to use an impulse grinder to break the hardened granulate to use. A vibrating tube mill is particularly suitable, order the desired sharp-edged from the hardened starting material To produce granules.

Für den Einsatz bei der Oberflächenbehandlung von metallischen Werkstücken ist es zweckmäßig, wenn das Strahlmittel nach der Korngröße klassiert vorliegt.
Hierzu kann dem erfindungsgemäßen Herstellungsverfahren ein weiterer Prozeßschritt zur Kornfraktionierung nachgeschaltet sein, mit dem die Einstellung der gewünschten Kornmischung erreicht wird. For use in the surface treatment of metallic workpieces, it is expedient if the abrasive is classified according to the grain size.
For this purpose, a further process step for grain fractionation, with which the setting of the desired grain mixture is achieved, can be connected downstream of the production method according to the invention.

Das erfindungsgemäße Verfahren wird im folgenden anhand der Zeichnung näher erläutert.The method according to the invention is described below with reference to the drawing explained in more detail.

Die Zeichnung zeigt ein Fließschema des Herstellungsverfahrens, wobei der obere Teil die Prozeßschritte zur Herstellung des Ausgangsgranulates umfaßt, während im unteren Teil das Härten, Brechen und Klassieren dargestellt sind.The drawing shows a flow diagram of the manufacturing process, the the upper part comprises the process steps for producing the starting granulate, while the lower part shows hardening, breaking and classifying.

Ausgangsmaterial für das Strahlmittel ist Stahtschrott, der dem Herstellungsprozeß aus einem Schrottlager 1 zugeführt wird. Zur Einstellung der gewünschten Legierung wird diesem aus geeigneten Vorratsbehältern Kohlenstoff in Form von Graphit 2 und Chrom 3 zugefügt. Die Rohstoffmischung wird dann in einem Schmelzofen 4 zu einer Legierung verschmolzen. Diese enthält 2,0% Kohlenstoff und 30% bis 32% Chrom.The starting material for the abrasive is steel scrap, which is the manufacturing process is fed from a scrap warehouse 1. To set the desired Alloy is shaped into carbon from suitable storage containers of graphite 2 and chrome 3 added. The raw material mixture is then in one Melting furnace 4 melted into an alloy. This contains 2.0% carbon and 30% to 32% chromium.

Die Schmelze durchläuft bei einer T emperatur von mehr als 1420° Celsius eine Verdüsungsvorrichtung 5, wobei ein Granulat mit einem breiten Spektrum von Korndurchmessem entsteht. Die verdüsten Tröpfchen der Metallschmelze werden in einem Wasserbad abgeschreckt, so daß sich festes Granulat am Boden eines Granulierungsbeckens 6 ansammelt.The melt passes through at a temperature of more than 1420 ° Celsius Spraying device 5, wherein a granulate with a wide range of Grain diameter arises. The atomized droplets of the molten metal become quenched in a water bath so that solid granules settle to the bottom a granulation basin 6 accumulates.

Das Granulat wird dem Becken aus einem Abzug 7 entnommen und durchläuft die Verfahrensschritte Abtropfen 8 und Trocknen 9. Nach Durchlaufen einer Kühlung 10 liegt das Ausgangsmaterial für die rostbeständige Chromgußlegierung vor.The granules are removed from the fume cupboard 7 and passed through the process steps of draining 8 and drying 9 Cooling 10 is the starting material for the rust-resistant Chrome cast alloy before.

Das Ausgangsgranulat wird nun einem Ofen 11 zugeführt, in dem es bei mehr als 900° Celsius in einer Atmosphäre von Wasserstoff und Stickstoff 13 bei niedrigem Druck geglüht und daran anschließend abgekühlt wird, wonach es in einen Vorratsbehälter 12 gefördert wird. Durch die Glühung des Granulates bei >900°C kommt es zur Ausscheidung von Sekundärkarbiden aus der legierungsreichen Matrix, wodurch sich die Zusammensetzung der Matrix verändert. Erst durch die Ausscheidung der Sekundärkarbide ist eine Martensitumwandlung möglich, die dann beim Abkühlen des Granulates von Temperaturen >900°C zu einer Härtesteigerung auf >60 HRC führt. The starting granulate is now fed to a furnace 11, in which it is annealed at more than 900 ° C. in an atmosphere of hydrogen and nitrogen 13 at low pressure and then cooled, after which it is conveyed into a storage container 12. By annealing the granulate at> 900 ° C, secondary carbides are separated from the alloy-rich matrix, which changes the composition of the matrix. A martensite conversion is only possible through the separation of the secondary carbides, which then leads to an increase in hardness to> 60 HR C when the granules cool down from temperatures> 900 ° C.

Aus dem Behälter 12 wird das Granulat mittels eines Becherwerkes 14 dem Brecher 15 zugeleitet. Der Brecher 15 ist vorzugsweise als Rohrschwingmühle ausgebildet und zerkleinert das gehärtete, spröde Granulat zu scharfkantigen Bruchkörpern. Durch die Verwendung von solchen Impulsmühlen gelingt es besonders gut, das unter starken inneren Spannungen stehende Material in scharfkantige Bruchstücke zu zerlegen. Die beim Brechen entstehende Kornmischung weist eine breite Größenverteilung auf. Zur Klassierung wird nun eine Siebanlage 16 durchlaufen. Zu grobes Überkorn 17 wird dem Brecher wieder zugeführt. Das zu feine Unterkorn 18 wird an dieser Stelle dem Prozeß entnommen und im Schmelzofen 4 eingeschmolzen. Gutkom 19 mit einem Durchmesser zwischen 0,1 und 0,8 mm wird entweder in einem Silo 20 gelagert oder zur Feinstklassierung einer weiteren Siebanlage 21 aufgegeben. Strahlmittel mit jeweils unterschiedlichen Korngrößen werden in den Silos 22, 23 und 24 bevorratet, bis sie zum Versand an den Endverbraucher entnommen werden.The granulate is removed from the container 12 by means of a bucket elevator 14 Crushers 15 fed. The crusher 15 is preferably a vibrating tube mill trained and crushed the hardened, brittle granules to sharp edges Failure bodies. The use of such pulse mills makes it possible especially good, the material under strong internal tension disassemble sharp-edged fragments. The one created when breaking Grain mix has a wide size distribution. Now for classification pass through a screening plant 16. The crusher becomes too coarse oversize 17 fed again. The too fine undersize 18 becomes the process at this point removed and melted in the melting furnace 4. Gutkom 19 with one Diameters between 0.1 and 0.8 mm are either stored in a silo 20 or abandoned for fine classification of another screening plant 21. Blasting media with different grain sizes are used in silos 22, 23 and 24 stocked until removed for shipment to the end user become.

Claims (6)

  1. A process for the production of blasting agent grains of stainless high-quality cast steel, wherein firstly a granular material is produced from the melt of a hardenable iron-chromium-carbon alloy, the granular material then passes through a heat treatment at > 900° Celsius for hardening and it is then broken up to form sharp-edged grains, characterised in that the heat treatment is effected in a reducing atmosphere and that exclusively a reducing gas or gas mixture is used for the subsequent cooling operation.
  2. A process according to claim 1 characterised in that the reducing atmosphere is a gas mixture which contains hydrogen and nitrogen.
  3. A process according to claim 2 characterised in that the gas mixture comprises from 60% to 80% hydrogen and from 20% to 40% nitrogen.
  4. A process according to claim 1 characterised in that the melt contains at least 2% carbon and at least 30% chromium.
  5. A process according to claim 1 characterised in that the operation of breaking the granular material is effected by means of a pulse mill, in particular a tube ball mill.
  6. A process according to claim 1 characterised in that a grain fractioning operation is then carried out to set various grain mixtures.
EP01942587A 2000-01-22 2001-01-11 Method for producing angular, stainless shot-blasting abrasives based on an fe-cr-c alloy Expired - Lifetime EP1250205B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10002738A DE10002738A1 (en) 2000-01-22 2000-01-22 Production of abrasive grains made of non-rusting cast stainless steel involves producing granules from a hardenable iron-chromium-carbon alloy melt, heat treating and cooling
DE10002738 2000-01-22
PCT/EP2001/000252 WO2001053022A1 (en) 2000-01-22 2001-01-11 Method for producing angular, stainless shot-blasting abrasives based on an fe-cr-c alloy

Publications (2)

Publication Number Publication Date
EP1250205A1 EP1250205A1 (en) 2002-10-23
EP1250205B1 true EP1250205B1 (en) 2003-06-25

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EP01942587A Expired - Lifetime EP1250205B1 (en) 2000-01-22 2001-01-11 Method for producing angular, stainless shot-blasting abrasives based on an fe-cr-c alloy

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US (1) US6764557B2 (en)
EP (1) EP1250205B1 (en)
JP (1) JP5085826B2 (en)
KR (1) KR100790097B1 (en)
CN (1) CN1245269C (en)
AT (1) ATE243594T1 (en)
AU (1) AU769520B2 (en)
BR (1) BR0107685A (en)
CA (1) CA2397953C (en)
CZ (1) CZ296109B6 (en)
DE (2) DE10002738A1 (en)
DK (1) DK1250205T3 (en)
EA (1) EA003956B1 (en)
ES (1) ES2202290T3 (en)
NZ (1) NZ520233A (en)
PT (1) PT1250205E (en)
SI (1) SI20913A (en)
UA (1) UA73545C2 (en)
WO (1) WO2001053022A1 (en)
ZA (1) ZA200205764B (en)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6797080B2 (en) * 2001-07-09 2004-09-28 Showa Denko Kabushiki Kaisha Method for producing spraying material
ITTV20010155A1 (en) * 2001-11-27 2003-05-27 Pometon S P A PROCEDURE FOR OBTAINING AN ABRASIVE MIXTURE PARTICULARLY FOR SEGMENT OF MARBLES AND PRODUCT SO OBTAINED
US20060285989A1 (en) * 2005-06-20 2006-12-21 Hoeganaes Corporation Corrosion resistant metallurgical powder compositions, methods, and compacted articles
CN102390044A (en) * 2011-10-25 2012-03-28 张铮 Steel grit manufacturing method
AT13691U1 (en) * 2013-09-02 2014-06-15 Plansee Se Chromium metal powder
FR3035607B1 (en) * 2015-04-30 2017-04-28 Saint-Gobain Centre De Rech Et D'Etudes Europeen METHOD FOR MODIFYING THE APPEARANCE OF A SURFACE
WO2019146530A1 (en) * 2018-01-25 2019-08-01 新東工業株式会社 Projection material and blasting method
DE102019133017A1 (en) * 2019-12-04 2021-06-10 Vulkan Inox Gmbh Abrasive for jet cutting

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GB2114605B (en) * 1982-01-21 1985-08-07 Davy Loewy Ltd Annealing steel powder
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JPS61257775A (en) * 1985-05-08 1986-11-15 Mitsubishi Heavy Ind Ltd Abrasive/cleaning material
JPS6299080A (en) * 1985-10-24 1987-05-08 Nippon Yakin Kogyo Co Ltd Metal grain for grinding/polishing/cleaning
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CZ20022532A3 (en) 2003-01-15
KR20020080380A (en) 2002-10-23
EA200200784A1 (en) 2003-02-27
CN1422194A (en) 2003-06-04
BR0107685A (en) 2002-11-19
PT1250205E (en) 2003-11-28
AU769520B2 (en) 2004-01-29
CN1245269C (en) 2006-03-15
NZ520233A (en) 2004-12-24
DK1250205T3 (en) 2003-09-29
ATE243594T1 (en) 2003-07-15
WO2001053022A1 (en) 2001-07-26
JP5085826B2 (en) 2012-11-28
CZ296109B6 (en) 2006-01-11
ZA200205764B (en) 2003-11-04
EA003956B1 (en) 2003-10-30
EP1250205A1 (en) 2002-10-23
CA2397953C (en) 2009-11-10
AU2846301A (en) 2001-07-31
DE10002738A1 (en) 2001-07-26
DE50100333D1 (en) 2003-07-31
SI20913A (en) 2002-12-31
CA2397953A1 (en) 2001-07-26
ES2202290T3 (en) 2004-04-01
JP2003524690A (en) 2003-08-19
UA73545C2 (en) 2005-08-15
US20030136224A1 (en) 2003-07-24
KR100790097B1 (en) 2007-12-31
US6764557B2 (en) 2004-07-20

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