EP0263373B1 - Process for manufacturing a wear-resistant sintered alloy - Google Patents
Process for manufacturing a wear-resistant sintered alloy Download PDFInfo
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- EP0263373B1 EP0263373B1 EP87114025A EP87114025A EP0263373B1 EP 0263373 B1 EP0263373 B1 EP 0263373B1 EP 87114025 A EP87114025 A EP 87114025A EP 87114025 A EP87114025 A EP 87114025A EP 0263373 B1 EP0263373 B1 EP 0263373B1
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- 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
- C22C33/0264—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements the maximum content of each alloying element not exceeding 5%
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- the invention relates to a method for producing a highly wear-resistant sintered alloy.
- Chilled cast iron is an iron-carbon alloy, in which the carbon and silicon content, in addition to the other elements manganese, phosphorus and sulfur, as well as nickel and chromium contents, are adjusted so that the base piece either completely by cooling in the molding sand or only by the action of quenching plates Solidified surface layer white. The carbon is therefore not excreted as graphite. The structure then consists of ledeburite with cementite or decayed austenite. Chilled cast iron is one of the best known, most wear-resistant alloys. The wear resistance is mostly achieved by cementite, more rarely by martensite, the latter can be achieved by appropriate alloying or by quenching. Chilled cast iron is practically not deformable.
- Powder metallurgy has proven itself for the production of bulk articles with qualified and specified properties.
- an iron-molybdenum-nickel sintered alloy with a phosphorus additive has been developed (DE-PS 26 13 255, AT-PS 361 959), and the objects made therefrom have a tensile strength of 600 N / mm2 and more, whereby these Parts are manufactured using the simple sintering technique and without additional heat treatment.
- Workpieces sintered from these alloys achieve the desired tensile strength, but not the wear resistance of chilled castings.
- an alloy of the desired composition is melted and atomized into powder using the conventional method. Since this process takes place under high-purity protective gas, it is ensured that the oxygen-affine element chromium also dissolves in the alloy.
- the powder obtained in this way is mixed with elemental carbon (graphite), pressed and sintered. Chromium forms carbides during sintering, which significantly improve wear resistance. The interaction of phosphorus and carbon cause the formation of a liquid phase and thus increase the sintering activity. Parts that are made from this pre-alloyed iron powder have a high shrinkage, the particles of the powder are very hard and therefore difficult to compress. The longitudinal shrinkage is in the range of 5%.
- the aim of the invention is therefore to propose a method for producing a highly wear-resistant sintered alloy with phosphorus additive, with which mass parts can be produced in essentially conventional sintering technology and without additional hardening treatment, with regard to their wear properties Chilled castings are equivalent. They should have a surface hardness of approx. 50 Rockwell (RC) and only a slight shrinkage, so the powder must be easy to compress.
- the workpiece manufactured with this sintered alloy should retain the character of powder metallurgical production, so it should have a not inconsiderable proportion of pores, which experience has shown to have a positive effect on the emergency running properties.
- the method for producing the sintered alloy for solving this complex task is defined by the features of patent claim 1.
- the method according to the invention for producing the highly wear-resistant sintered alloy is characterized in that the carbon content by weight is up to 5 times as large as the phosphorus content.
- GB-A-2 156 851 gives a wear-resistant sintered alloy of 1.5 - 3.5% C, 0.3 - 1.0% P, 0.5 - 3.0% Mo, 0.5 - 5.0% Ni and / or Cu (where Cu can replace Ni with a conversion rate of 0.5 for Cu), the rest iron is phosphated.
- the examples given contain Ni or Cu alone or both components.
- the state of the art says nothing more than that the elements manganese, silicon, sulfur and phosphorus make up no more than 2 percent by weight. It is reasonable to assume that the four components are approximately equally important in this summary. Assuming a proportion of 0.5 percent by weight for each of these four alloy elements, the prior art makes only a fraction of the inventive concept, namely only when the carbon content is above 1.5%. If the relevant specialist works according to the teaching of the prior art, his success rate with respect to the present invention is (2.0-1.5): (2.0-0.3), therefore, less than 30%.
- Bulk parts made from this alloy according to the invention do not have to be subjected to a hardening process, they have surface hardnesses in the range of approximately 50 Rockwell (RC) and only slight shrinkage or growth. They also have the character of a powder metallurgically manufactured workpiece, that is to say they have a relatively high proportion of pores, which favors the emergency running properties.
- the constituents of the sintered alloy are mixed in elemental form with iron powder or diffusion alloyed, the powder obtained in this way is shaped in a press tool to the desired part under pressure, for example under pressures of 400-1000 N / mm 2 and then at about 1120 ° C.
- the sintering process in a manner known per se essentially comprising three immediately consecutive time phases, namely the smoking of the lubricant, the actual sintering and the cooling, these processes taking place under protective gas.
- the good compressibility is ensured by the fact that the components are elementary in the alloyed powder and thus the good deformability of pure metals can be used.
- the cementite network can be seen in the micrograph as a white network. It encloses almost all grains. Its thickness is less than 3 ⁇ m, in most places the thickness is 1 ⁇ m.
- the white dots that can be seen in a few places inside the grain are cementite balls.
- the structure of the grains consists of acicular (needle-like) martensite, which is embedded in residual austenite.
- the martensite appears in the form of dark needles, the resaustenite lies in between.
- a volume fraction of 40% for the residual austenite is to be expected with this alloy.
- a volume fraction of 14% there are areas rich in austenite (light spots in Fig. 1), which are partially intersected by the cementite network.
- the slight gray coloration of the residual austenite could indicate a partial transformation into lower bainite by the tempering treatment.
- Residual austenite can have an adverse effect on the dimensional stability of the components. Nevertheless, the appearance of residual austenite in the structure does not have to be a disadvantage in terms of wear. With increasing volume of residual austenite, the resistance to abrasive wear increases. The conversion of the residual austenite into bainite represents an advantage in the case of sliding wear. With the same hardness, a bainitic structure has better sliding wear properties than a martensitic one.
- micro load hardness tests showed a hardness of 612 ⁇ 23 HV 0.05 for the martensitic grains. In areas with a high proportion of austenite (or lower bainite), the hardness is significantly lower at 476 ⁇ 88.
- the cementite network is stronger than that of the alloy discussed first. It encloses all grains.
- the thickness is between 1 ⁇ m and 15 ⁇ m, with particularly wide areas of the cementite network being observed at triple grain boundary points.
- the cementite grains that occur sporadically in the alloy discussed first occur here increasingly.
- Well-rounded cementite grains (hardness 1018 HV 0.025) can be seen in almost every grain.
- the martensitic areas are somewhat harder than those of the alloy discussed first. In contrast, the remaining austenite areas are softer at 353 ⁇ 36 HV 0.05.
- the cementite network has the expected hardness of 1035 ⁇ 67 HV 0.05.
Abstract
Description
Die Erfindung bezieht sich auf ein Verfahren zur Herstellung einer hochverschleißfesten Sinterlegierung.The invention relates to a method for producing a highly wear-resistant sintered alloy.
Es ist bekannt, hochverschleißfeste Maschinenbauteile aus Hartguß herzustellen. Hartguß ist eine Eisen-Kohlenstofflegierung, bei der der Kohlenstoff- und Siliziumgehalt neben den übrigen Elementen Mangan, Phosphor und Schwefel sowie Nickel- und Chromgehalte so eingestellt werden, daß das Fußstück entweder durch die Abkühlung im Formsand völlig oder durch die Wirkung von Abschreckplatten nur eine Oberflächenschichte weiß erstarrt. Der Kohlenstoff wird also nicht als Graphit ausgeschieden. Das Gefüge besteht dann aus Ledeburit mit Zementit oder zerfallenem Austenit. Hartguß gehört zu den bekanntesten, verschleißbeständigsten Legierungen. Die Verschleißbeständigkeit wird meist durch Zementit, seltener durch Martensit erreicht, letzteres kann durch entsprechendes Legieren oder durch Abschrecken erzielt werden. Hartguß ist praktisch nicht verformungsfähig.It is known to manufacture highly wear-resistant machine components from chilled cast iron. Chilled cast iron is an iron-carbon alloy, in which the carbon and silicon content, in addition to the other elements manganese, phosphorus and sulfur, as well as nickel and chromium contents, are adjusted so that the base piece either completely by cooling in the molding sand or only by the action of quenching plates Solidified surface layer white. The carbon is therefore not excreted as graphite. The structure then consists of ledeburite with cementite or decayed austenite. Chilled cast iron is one of the best known, most wear-resistant alloys. The wear resistance is mostly achieved by cementite, more rarely by martensite, the latter can be achieved by appropriate alloying or by quenching. Chilled cast iron is practically not deformable.
Wenngleich sich dieser Werkstoff für hoch verschleißfeste Maschinenbauteile bestens bewährt hat, liegt der ihm anhaftende Nachteil darin, daß sich die Herstellung von Hartgußteilen bislang nicht automatisieren läßt, so daß die Herstellung solcher Teile sehr teuer ist, vor allem dann, wenn es sich um die Herstellung von Massenartikel handelt, die in großen Stückzahlen gefertigt werden müssen.Although this material has proven itself very well for highly wear-resistant machine components, the disadvantage that is inherent in it is that the production of chilled castings has not hitherto been able to be automated, so that the production of such parts is very expensive, especially when it comes to production deals with mass articles that have to be manufactured in large quantities.
Für die Herstellung von Massenartikel mit qualifizierten und spezifizierten Eigenschaften hat sich die Pulvermetallurgie bewährt. Zur Herstellung hochfester Werkstücke wurde dafür eine Eisen-Molybdän-Nickel-Sinterlegierung mit Phosphorzusatz entwickelt (DE-PS 26 13 255, AT-PS 361 959), und die daraus hergestellten Gegenstände besitzen eine Zugfestigkeit von 600 N/mm² und mehr, wobei diese Teile unter Anwendung der einfachen Sintertechnik hergestellt werden, und zwar ohne zusätzliche Wärmebehandlung. Werkstücke, die aus diesen Legierungen gesintert sind, erreichen zwar die gewünschte Zugfestigkeit, nicht jedoch die Verschleißfestigkeit von Hartgußteilen.Powder metallurgy has proven itself for the production of bulk articles with qualified and specified properties. For the production of high-strength workpieces, an iron-molybdenum-nickel sintered alloy with a phosphorus additive has been developed (DE-PS 26 13 255, AT-PS 361 959), and the objects made therefrom have a tensile strength of 600 N / mm² and more, whereby these Parts are manufactured using the simple sintering technique and without additional heat treatment. Workpieces sintered from these alloys achieve the desired tensile strength, but not the wear resistance of chilled castings.
Für Nocken von Nockenwellen, für welche eine hohe Verschleißfestigkeit zu fordern ist, wurde eine Sinterlegierung entwickelt, welche Chrom, Molybdän, Kupfer, Phosphor und Kohlenstoff enthält (GB-OS 20 73 247, Höganaes-PM-Seminarbericht/März 1985)). Es wurden Vergleichsteste durchgeführt, wobei Hartgußnockenwellen und solche mit gesinterten Nocken aus dem genannten Werkstoff gleichen Prüfungsbedingungen unterworfen wurden. Die dabei ermittelten Verschleißwerte liegen in vergleichbaren Größenbereichen. Die hier verwendete Sinterlegierung kann jedoch nicht durch ein einfaches Mischen der entsprechenden elementaren Metallpulver hergestellt werden, sondern muß aufgrund der hohen Sauerstoffaffinität von Chrom als vorlegiertes Pulver eingesetzt werden. Würde Chrom elementar als Pulver beigemischt, würde sich vor der eigentlichen Sinterung ein Oxidmantel um die Teilchen bilden, da die in der Technik verwendeten Schutzgase meistens mit Sauerstoff verunreinigt sind. Der Oxidmantel verhindert den diffusionsgesteuerten Legierungsprozeß.For cams of camshafts, for which a high wear resistance too a sintered alloy was developed which contains chromium, molybdenum, copper, phosphorus and carbon (GB-OS 20 73 247, Höganaes-PM seminar report / March 1985)). Comparative tests were carried out, with chilled cast camshafts and those with sintered cams made of the material mentioned being subjected to the same test conditions. The wear values determined are in comparable size ranges. However, the sintered alloy used here cannot be produced by simply mixing the corresponding elementary metal powder, but must be used as a pre-alloyed powder due to the high oxygen affinity of chromium. If chromium were added elementally as a powder, an oxide coat would form around the particles before the actual sintering, since the protective gases used in technology are mostly contaminated with oxygen. The oxide coating prevents the diffusion-controlled alloy process.
Zur Herstellung von vorlegierten Pulvern wird eine Legierung der gewünschten Zusammensetzung verschmolzen und nach dem herkömmlichen Verfahren zu Pulver verdüst. Da dieser Prozeß unter hochreinem Schutzgas verläuft, ist gewährleistet, daß sich auch das sauerstoffaffine Element Chrom in der Legierung löst. Das so gewonnene Pulver wird mit elementarem Kohlenstoff (Graphit) gemischt, verpreßt und gesintert. Chrom bildet während des Sinterns Carbide, die die Verschleißfähigkeit erheblich verbessern. Die Zusammenwirkung von Phosphor und Kohlenstoff verursachen die Bildung einer flüssigen Phase und erhöhen damit die Sinteraktivität. Teile, die aus diesem vorlegierten Eisenpulver hergestellt werden, besitzen eine hohe Schrumpfung, die Teilchen des Pulvers sind sehr hart und daher nur schlecht verpreßbar. Die Schrumpfung in Längsrichtung liegt im Bereich von 5 %. Bei der Herstellung von Nocken für Nockenwellen ist diese Schrumpfung nicht ganz unerwünscht, weil dadurch ein fester Sitz des Nockens auf der Welle erreicht werden kann. Andererseits jedoch können aufgrund der hohen Schrumpfung keine engen Toleranzen eingehalten werden oder nur mit großem Aufwand. Die Herstellung eines vorlegierten Pulvers ist aufwendig und damit teuer.To produce pre-alloyed powders, an alloy of the desired composition is melted and atomized into powder using the conventional method. Since this process takes place under high-purity protective gas, it is ensured that the oxygen-affine element chromium also dissolves in the alloy. The powder obtained in this way is mixed with elemental carbon (graphite), pressed and sintered. Chromium forms carbides during sintering, which significantly improve wear resistance. The interaction of phosphorus and carbon cause the formation of a liquid phase and thus increase the sintering activity. Parts that are made from this pre-alloyed iron powder have a high shrinkage, the particles of the powder are very hard and therefore difficult to compress. The longitudinal shrinkage is in the range of 5%. This shrinkage is not entirely undesirable in the production of cams for camshafts, because it enables the cam to be firmly seated on the shaft. On the other hand, due to the high shrinkage, tight tolerances cannot be maintained or only with great effort. The production of a pre-alloyed powder is complex and therefore expensive.
Ziel der Erfindung ist es daher, ein Verfahren zur Herstellung einer hochverschleißfesten Sinterlegierung mit Phosphorzusatz vorzuschlagen, mit welchem in im wesentlichen herkömmlicher Sintertechnik und ohne zusätzliche Härtebehandlung Masseteile erzeugt werden können, die hinsichtlich ihrer Verschleißeigenschaften Hartgußteilen gleichwertig sind. Sie sollen also eine Oberflächenhärte von ca. 50 Rockwell (RC) besitzen und nur eine geringe Schrumpfung, das Pulver muß also gut verpreßbar sein. Dabei soll das mit dieser Sinterlegierung gefertgte Werkstück den Charakter der pulvermetallurgischen Herstellung beibehalten, es soll also einen nicht unerheblichen Porenanteil besitzen, der sich erfahrungsgemäß positiv auf die Notlaufeigenschaften auswirkt. Erfindungsgemäß ist das Verfahren zur Herstellung der Sinterlegierung zur Lösung dieser komplexen Aufgabe durch die Merkmale des Patentanspruches 1 definiert.The aim of the invention is therefore to propose a method for producing a highly wear-resistant sintered alloy with phosphorus additive, with which mass parts can be produced in essentially conventional sintering technology and without additional hardening treatment, with regard to their wear properties Chilled castings are equivalent. They should have a surface hardness of approx. 50 Rockwell (RC) and only a slight shrinkage, so the powder must be easy to compress. The workpiece manufactured with this sintered alloy should retain the character of powder metallurgical production, so it should have a not inconsiderable proportion of pores, which experience has shown to have a positive effect on the emergency running properties. According to the invention, the method for producing the sintered alloy for solving this complex task is defined by the features of patent claim 1.
Insbesondere ist das erfindungsgemäße Verfahren zur Herstellung der hochverschleißfesten Sinterlegierung dadurch gekennzeichnet, daß der gewichtsmäßige Kohlenstoffgehalt bis zu 5 mal so groß ist wie der Phosphorgehalt.In particular, the method according to the invention for producing the highly wear-resistant sintered alloy is characterized in that the carbon content by weight is up to 5 times as large as the phosphorus content.
GB-A-2 156 851 gibt eine verschleißfeste Sinterlegierung aus 1,5 - 3,5 % C, 0,3 - 1,0 % P, 0,5 - 3,0 % Mo, 0,5 - 5,0 % Ni und/oder Cu, (wobei Cu das Ni ersetzen kann mit einer Umrechnungsrate von 0,5 für Cu), Rest Eisen an die phosphatiert wird. Die angegebenen Beispiele enthalten entwerden Ni oder Cu alleine oder beide Komponenten. In diesem Zusammenhang ist auch auf die Legierung hinzuweisen, die aus der DE-OS 28 31 548 bekannt ist, und bei der die Legierungsbereiche für Nickel, Kupfer und Molybdän diejenigen der vorliegenden Erfindung umfassen. Hinsichtlich des Kohlenstoffgehaltes liegt die Obergrenze geringfügig außerhalb des Standes der Technik. Bezüglich des Phosphorgehaltes sagt der Stand der Technik nichts weiter aus, als daß die Elemente Mangan, Silizium, Schwefel und Phosphor insgesamt nicht mehr als 2 Gewichtsprozente ausmachen. Vernüftigerweise wird man davon ausgehen, daß bei dieser summarischen Angabe die vier Komponenten etwa gleich-gewichtig vorhanden sind. Unterstellt man also einen Anteil von 0,5 Gewichtsprozenten für jedes dieser vier Legierungselemente, so macht der Stand der Technik nur zum Bruchteil vom Erfindungsgedanken Gebrauch, nämlich nur dann, wenn der Kohlenstoffgehalt oberhalb 1,5 % liegt. Arbeitet also der einschlägige Fachmann nach der Lehre des Standes der Technik, so ist seine Erfolgsquote bezüglich der vorliegenden Erfindung (2,0 - 1,5) : (2,0 - 0,3) also geringer als 30 %. Die summarische Zusammenfassung der vier genannten Legierungselemente einschließlich Phosphor mit einer Gesamtobergrenze, wie in der letzterwähnten Vorveröffentlichung angegeben, kann nur so aufgefaßt werden, daß es auf deren Einzelgewichtsanteile überhaupt nicht ankommt. Dem gegenüber besteht die erfindungsgemäße Einstellregel gerade darin, ein Mindestverhältnis von Kohlenstoffanteil zu Phosphoranteil vorzuschreiben. Hier kommt es also auf den Phosphorgehalt entscheidend an.GB-A-2 156 851 gives a wear-resistant sintered alloy of 1.5 - 3.5% C, 0.3 - 1.0% P, 0.5 - 3.0% Mo, 0.5 - 5.0% Ni and / or Cu (where Cu can replace Ni with a conversion rate of 0.5 for Cu), the rest iron is phosphated. The examples given contain Ni or Cu alone or both components. In this context, reference should also be made to the alloy which is known from DE-OS 28 31 548 and in which the alloy ranges for nickel, copper and molybdenum include those of the present invention. With regard to the carbon content, the upper limit is slightly outside the prior art. With regard to the phosphorus content, the state of the art says nothing more than that the elements manganese, silicon, sulfur and phosphorus make up no more than 2 percent by weight. It is reasonable to assume that the four components are approximately equally important in this summary. Assuming a proportion of 0.5 percent by weight for each of these four alloy elements, the prior art makes only a fraction of the inventive concept, namely only when the carbon content is above 1.5%. If the relevant specialist works according to the teaching of the prior art, his success rate with respect to the present invention is (2.0-1.5): (2.0-0.3), therefore, less than 30%. The summary summary of the four alloy elements mentioned, including phosphorus with an overall upper limit, as stated in the last-mentioned prior publication, can only be understood in such a way that their individual weight fractions are irrelevant. In contrast, the setting rule according to the invention consists precisely in prescribing a minimum ratio of carbon to phosphorus. Here the phosphorus content is crucial.
Massenteile, die aus dieser erfindungsgemäßen Legierung hergestellt sind, müssen keinem Härteverfahren unterworfen werden, sie besitzen Oberflächenhärten im Bereich von ca. 50 Rockwell (RC) und nur eine geringe Schrumpfung bzw. nur ein geringes Wachstum. Sie weisen ferner den Charakter eines pulver metallurgisch hergestellten Werksstückes auf, das heißt, sie besitzen einen relativ hohen Porenanteil, der die Notlaufeigenschaften begünstigt. Die die Sinterlegierung bildenden Bestandteile werden in elementarer Form mit Eisenpulver gemischt bzw. diffusionslegiert, das so erhaltene Pulver wird in einem Preßwerkzeug zum gewünschten Teil unter Druck, beispielsweise unter Drücken von 400 - 1000 N/mm² geformt und anschließend bei 1120° C während zirka dreißig Minuten gesintert, wobei der Sintervorgang in an sich bekannter Weise im wesentlichen drei unmittelbar aufeinanderfolgende Zeitphasen umfaßt, nämlich das Abrauchen des Schmiermittels, das eigentliche Sintern und das Abkühlen, wobei diese Vorgänge unter Schutzgas verlaufen. Die gute Verpreßbarkeit wird dadurch gewährleistet, daß beim anlegierten Pulver die Kompnenten elementar vorliegen und damit die gute Verformbarkeit reiner Metalle genutzt werden kann.Bulk parts made from this alloy according to the invention do not have to be subjected to a hardening process, they have surface hardnesses in the range of approximately 50 Rockwell (RC) and only slight shrinkage or growth. They also have the character of a powder metallurgically manufactured workpiece, that is to say they have a relatively high proportion of pores, which favors the emergency running properties. The constituents of the sintered alloy are mixed in elemental form with iron powder or diffusion alloyed, the powder obtained in this way is shaped in a press tool to the desired part under pressure, for example under pressures of 400-1000 N / mm 2 and then at about 1120 ° C. for about thirty Minutes sintered, the sintering process in a manner known per se essentially comprising three immediately consecutive time phases, namely the smoking of the lubricant, the actual sintering and the cooling, these processes taking place under protective gas. The good compressibility is ensured by the fact that the components are elementary in the alloyed powder and thus the good deformability of pure metals can be used.
Die folgenden beiden Beispiele erläutern näher die Erfindung, wobei diese Beispiele die genaue Zusammensetzung der Legierung, die erzielte Preßdichte des Rohlings, sowie die gewonnene Oberflächenhärte anzeigen, die nach genormten Meßmethoden ermittelt worden ist.The following two examples explain the invention in more detail, these examples indicating the precise composition of the alloy, the compression density of the blank obtained and the surface hardness obtained, which has been determined using standardized measuring methods.
- Nennanalyse:
- C 1,5 %
Cu 1,5 %
Ni 4 %
Mo 0,5 %
P 0,45 %
Fe Rest
Anlaßtemperatur: 175 ° C
Anlaßzeit: 60 Minuten
Nenndichte: 7,0 gr/cm³
Härte HV 5 ≃ 520
Fig. 1 zeigt ein Schliffbild (500-fache Vergrößerung). Der Schliff wurde in herkömmlicher Weise hergestellt. Diese Legierung weist kleine abgerundete Poren auf. Die Poren befinden sich hauptsächlich auf den durch das Zementitnetz markierten Krongrenzen. An verschiedenen Stellen liegen kleinere Poren mitten im Korn.
- Nominal analysis:
- C 1.5%
Cu 1.5%
Ni 4%
Mo 0.5%
P 0.45%
Fe rest
Tempering temperature: 175 ° C
Starting time: 60 minutes
Nominal density: 7.0 gr / cm³
Hardness HV 5 ≃ 520
Fig. 1 shows a micrograph (500 times magnification). The cut was in conventionally manufactured. This alloy has small rounded pores. The pores are mainly on the crown boundaries marked by the cementite network. In various places there are smaller pores in the middle of the grain.
Das Zementitnetz ist im Schliffbild als weißes Netz zu erkennen. Es umschließt fast sämliche Körner. Seine Dicke beträgt weniger als 3 µm, an den meisten Stellen liegt die Dicke bei 1 µm. Bei den weißen Punkten, die an wenigen Stellen im Korninneren zu sehen sind, handelt es sich um Zementitkugeln.The cementite network can be seen in the micrograph as a white network. It encloses almost all grains. Its thickness is less than 3 µm, in most places the thickness is 1 µm. The white dots that can be seen in a few places inside the grain are cementite balls.
Das Gefüge der Körner besteht aus acicularem (nadeligem) Martensit, der in Restaustenit eingebettet ist. Der Martensit erscheint in Form dunkler Nadeln, der Resaustenit liegt hell dazwischen. Entsprechend der Fig. 1 ist bei dieser Legierung ein Volumenanteil von 40 % für den Restaustenit zu erwarten. Demgemäß finden sich mit einem Volumenanteil von 14 % restaustenitreiche Gebiete (helle Flecken in Fig. 1), die stellenweise vom Zementitnetz durchschnitten werden. Die leichte Graufärbung des Restaustenits könnte auf eine teilweise Umwandlung in unteren Bainit durch die Anlaßbehandlung hinweisen.The structure of the grains consists of acicular (needle-like) martensite, which is embedded in residual austenite. The martensite appears in the form of dark needles, the resaustenite lies in between. According to FIG. 1, a volume fraction of 40% for the residual austenite is to be expected with this alloy. Accordingly, with a volume fraction of 14%, there are areas rich in austenite (light spots in Fig. 1), which are partially intersected by the cementite network. The slight gray coloration of the residual austenite could indicate a partial transformation into lower bainite by the tempering treatment.
Restaustenit kann sich ungünstig auf die Maßbeständigkeit der Bauteile auswirken. Dennoch muß das Auftreten von Restaustenit im Gefüge keinen Nachteil bezüglich des Verschleisses darstellen. Mit wachsendem Volumenanteil an Restaustenit wird der Widerstand gegen abrasiven Verschleiß erhöht. Die Umwandlung des Restaustenits in Bainit stellt einen Vorteil bei Gleitverschleißbeanspruchung dar. Bei gleicher Härte hat ein bainitisches Gefüge bessere Gleitverschleißeigenschaften als ein martensitisches.Residual austenite can have an adverse effect on the dimensional stability of the components. Nevertheless, the appearance of residual austenite in the structure does not have to be a disadvantage in terms of wear. With increasing volume of residual austenite, the resistance to abrasive wear increases. The conversion of the residual austenite into bainite represents an advantage in the case of sliding wear. With the same hardness, a bainitic structure has better sliding wear properties than a martensitic one.
Die Mikrolasthärteprüfungen ergaben eine Härte von 612±23 HV 0,05 für die martensitischen Körner. In Gebieten mit hohem Restaustenitanteil (bzw. unterem Bainit) liegt die Härte mit 476±88 deutlich niedriger.The micro load hardness tests showed a hardness of 612 ± 23 HV 0.05 for the martensitic grains. In areas with a high proportion of austenite (or lower bainite), the hardness is significantly lower at 476 ± 88.
- Nennanalyse:
- C 2 %
Cu 1,5 %
Ni 1,75 %
Mo 0,5 %
P 0,45 %
Fe Rest
Anlaßtemperatur: 175° C
Anlaßzeit: 60 Minuten
Nenndichte: 7,0 gr/cm³
Härte HV 5 ≃ 520
Fig. 2 zeigt das Schliffbild (500-fache Vergrößerung). Die Poren dieser Legierung sind größer und besser abgerundet als die der erstbesprochenen Legierung. Sie liegen vorzugsweise an Korngrenzentripelpunkten, seltener zwischen zwei Körnern und nur in wenigen Fällen im Korninneren. Die bessere Rundung weist auf eine verstärkt auftretende flüssige Phase während der Sinterung hin.
- Nominal analysis:
- C 2%
Cu 1.5%
Ni 1.75%
Mo 0.5%
P 0.45%
Fe rest
Tempering temperature: 175 ° C
Starting time: 60 minutes
Nominal density: 7.0 gr / cm³
Hardness HV 5 ≃ 520
Fig. 2 shows the micrograph (500 times magnification). The pores of this alloy are larger and better rounded than those of the alloy discussed first. They are preferably at triple grain boundary points, less often between two grains and only in a few cases inside the grain. The better rounding indicates an increased liquid phase during sintering.
Das Zementitnetz ist stärker als bei der erstbesprochenen Legierung. Es umschließt sämtliche Körner. Die Dicke liegt bei 1 µm bis 15 µm, wobei an Korngrenzentripelpunkten besonders breite Stellen des Zementitnetzes zu beobachten sind. Die bei der erstbesprochenen Legierung vereinzelt auftretenden Zementitkörner treten hier vermehrt auf. Fast in jedem Korn sind die gut gerundeten Zementitkörner (Härte 1018 HV 0,025) zu erkennen.The cementite network is stronger than that of the alloy discussed first. It encloses all grains. The thickness is between 1 µm and 15 µm, with particularly wide areas of the cementite network being observed at triple grain boundary points. The cementite grains that occur sporadically in the alloy discussed first occur here increasingly. Well-rounded cementite grains (hardness 1018 HV 0.025) can be seen in almost every grain.
Die Körner selbst bestehen wie bei der erstbesprochenen Legierung aus acicularem Martensit mit Restaustenit. Restaustenitreiche Gebiete befinden sich meistens im Korninneren, teilweise liegen auch größere Gebiete vor, die von mehreren benachbarten Körner gebildet werden und nur durch das Zementitnetz getrennt sind.The grains themselves consist of acicular martensite with residual austenite, as in the alloy discussed first. Areas rich in austenite are mostly found in the interior of the grain, in some cases there are larger areas that are formed by several neighboring grains and are only separated by the cementite network.
Die martensitischen Gebiete sind mit 680±69 HV 0,05 etwas härter als die der erstbesprochenen Legierung. Dagegen sind die restaustenitreichen Gebiete mit 353±36 HV 0,05 weicher. Das Zementitnetz weist die erwartete Härte von 1035± 67 HV 0,05 auf.At 680 ± 69 HV 0.05, the martensitic areas are somewhat harder than those of the alloy discussed first. In contrast, the remaining austenite areas are softer at 353 ± 36 HV 0.05. The cementite network has the expected hardness of 1035 ± 67 HV 0.05.
Claims (2)
- A method of manufacturing a highly wear-resistant sintered alloy which comprises 1.0 to 5.0 wt.% nickel, 1.0 to 3.0 wt.% copper, 0.3 to 1.0 wt.% molybdenum, 1.0 to 2.5 wt.% carbon as well as phosphorus and the remainder iron, the phosphorus content lying in the region of 0.3 to 0.6 wt.% and the carbon content being adjusted in relation to the phosphorus content in such a way that it is at least twice as great by weight as the latter.
- A method according to claim 1, characterised in that the carbon content by weight is up to 5 times as great as the phosphorus content.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT87114025T ATE77846T1 (en) | 1986-10-04 | 1987-09-25 | PROCESS FOR MANUFACTURING A HIGHLY WEAR-RESISTANT SINTERED ALLOY. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3633879 | 1986-10-04 | ||
| DE19863633879 DE3633879A1 (en) | 1986-10-04 | 1986-10-04 | HIGH-WEAR-RESISTANT IRON-NICKEL-COPPER-MOLYBDAEN-SINTER ALLOY WITH PHOSPHORUS ADDITIVE |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0263373A2 EP0263373A2 (en) | 1988-04-13 |
| EP0263373A3 EP0263373A3 (en) | 1989-08-02 |
| EP0263373B1 true EP0263373B1 (en) | 1992-07-01 |
Family
ID=6311076
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP87114025A Expired - Lifetime EP0263373B1 (en) | 1986-10-04 | 1987-09-25 | Process for manufacturing a wear-resistant sintered alloy |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4909843A (en) |
| EP (1) | EP0263373B1 (en) |
| AT (1) | ATE77846T1 (en) |
| DE (2) | DE3633879A1 (en) |
| ES (1) | ES2033761T3 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3520093B2 (en) * | 1991-02-27 | 2004-04-19 | 本田技研工業株式会社 | Secondary hardening type high temperature wear resistant sintered alloy |
| GB9405946D0 (en) * | 1994-03-25 | 1994-05-11 | Brico Eng | Sintered valve seat insert |
| SE9401823D0 (en) * | 1994-05-27 | 1994-05-27 | Hoeganaes Ab | Nickel free iron powder |
| US5552109A (en) * | 1995-06-29 | 1996-09-03 | Shivanath; Rohith | Hi-density sintered alloy and spheroidization method for pre-alloyed powders |
| JP3447030B2 (en) * | 1996-01-19 | 2003-09-16 | 日立粉末冶金株式会社 | Wear resistant sintered alloy and method for producing the same |
Family Cites Families (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS549127B2 (en) * | 1971-06-28 | 1979-04-21 | ||
| US3837816A (en) * | 1972-09-05 | 1974-09-24 | Nippon Piston Ring Co Ltd | Thermal and abrasion resistant sintered alloy |
| JPS5835256B2 (en) * | 1976-02-11 | 1983-08-01 | 住友電気工業株式会社 | combination sliding member |
| DE2613255C2 (en) * | 1976-03-27 | 1982-07-29 | Robert Bosch Gmbh, 7000 Stuttgart | Use of an iron-molybdenum-nickel sintered alloy with the addition of phosphorus for the production of high-strength workpieces |
| SE7612279L (en) * | 1976-11-05 | 1978-05-05 | British Steel Corp | FINALLY DISTRIBUTED STEEL POWDER, AND WAY TO PRODUCE THIS. |
| GB1576143A (en) * | 1977-07-20 | 1980-10-01 | Brico Eng | Sintered metal articles |
| JPS609587B2 (en) * | 1978-06-23 | 1985-03-11 | トヨタ自動車株式会社 | Wear-resistant sintered alloy |
| US4170474A (en) * | 1978-10-23 | 1979-10-09 | Pitney-Bowes | Powder metal composition |
| JPS55145151A (en) * | 1979-04-26 | 1980-11-12 | Nippon Piston Ring Co Ltd | Wear resistant sintered alloy material for internal combustion engine |
| JPS55145152A (en) * | 1979-04-26 | 1980-11-12 | Nippon Piston Ring Co Ltd | Sintered alloy material for internal combustion engine |
| JPS55164060A (en) * | 1979-05-07 | 1980-12-20 | Nippon Piston Ring Co Ltd | Abrasion resistant iron-based sintered alloy material |
| JPS5918463B2 (en) * | 1980-03-04 | 1984-04-27 | トヨタ自動車株式会社 | Wear-resistant sintered alloy and its manufacturing method |
| JPS5767148A (en) * | 1980-10-09 | 1982-04-23 | Mitsubishi Metal Corp | Sintered roller chain bush containing coil |
| JPS5881954A (en) * | 1981-11-09 | 1983-05-17 | Mitsubishi Metal Corp | High strength iron base sintered alloy excellent in wear resistance and self-lubricating property |
| JPS5993855A (en) * | 1982-11-18 | 1984-05-30 | Mitsubishi Metal Corp | Fe-base sintered material with high strength |
| JPS6070163A (en) * | 1983-09-28 | 1985-04-20 | Nippon Piston Ring Co Ltd | Wear resistant sintered alloy member |
| JPS6075501A (en) * | 1983-09-29 | 1985-04-27 | Kawasaki Steel Corp | Alloy steel powder for high strength sintered parts |
| JPS60152658A (en) * | 1984-01-20 | 1985-08-10 | Nissan Motor Co Ltd | Wear resistant sintered alloy |
| JPS60169541A (en) * | 1984-02-10 | 1985-09-03 | Hitachi Powdered Metals Co Ltd | Manufacture of precipitation hardening sintered alloy |
| JPS61243156A (en) * | 1985-04-17 | 1986-10-29 | Hitachi Powdered Metals Co Ltd | Wear resistant iron series sintered alloy and its production |
| AT382334B (en) * | 1985-04-30 | 1987-02-10 | Miba Sintermetall Ag | CAMS FOR SHRINKING ON A CAMSHAFT AND METHOD FOR PRODUCING SUCH A CAM BY SINTERING |
| JPS62271914A (en) * | 1986-04-11 | 1987-11-26 | Nippon Piston Ring Co Ltd | Sintered cam shaft |
-
1986
- 1986-10-04 DE DE19863633879 patent/DE3633879A1/en active Granted
-
1987
- 1987-09-25 ES ES198787114025T patent/ES2033761T3/en not_active Expired - Lifetime
- 1987-09-25 AT AT87114025T patent/ATE77846T1/en not_active IP Right Cessation
- 1987-09-25 EP EP87114025A patent/EP0263373B1/en not_active Expired - Lifetime
- 1987-09-25 DE DE8787114025T patent/DE3780114D1/en not_active Expired - Fee Related
- 1987-10-02 US US07/104,654 patent/US4909843A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| ATE77846T1 (en) | 1992-07-15 |
| ES2033761T3 (en) | 1993-04-01 |
| EP0263373A3 (en) | 1989-08-02 |
| US4909843A (en) | 1990-03-20 |
| EP0263373A2 (en) | 1988-04-13 |
| DE3633879C2 (en) | 1992-01-16 |
| DE3780114D1 (en) | 1992-08-06 |
| DE3633879A1 (en) | 1988-04-14 |
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