EP0141804B1 - Hadfield type manganese steel and process for the manufacture thereof - Google Patents

Hadfield type manganese steel and process for the manufacture thereof Download PDF

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Publication number
EP0141804B1
EP0141804B1 EP84890187A EP84890187A EP0141804B1 EP 0141804 B1 EP0141804 B1 EP 0141804B1 EP 84890187 A EP84890187 A EP 84890187A EP 84890187 A EP84890187 A EP 84890187A EP 0141804 B1 EP0141804 B1 EP 0141804B1
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manganese
temperature
weight
melt
content
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EP0141804A1 (en
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Bernd Dipl.-Ing. Kos
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Vereinigte Edelstahlwerke AG
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Vereinigte Edelstahlwerke AG
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/04Ferrous alloys, e.g. steel alloys containing manganese

Definitions

  • the invention relates to a strain-hardening austenitic manganese steel (Hadfield steel) with an elongation at break of 10 - 80% and to a method for the production.
  • Hadfield steel strain-hardening austenitic manganese steel
  • Cold-hardening austenitic manganese steels have a large area of application in the form of castings, forgings and rolled products. This large area of application results above all from its own high ductility and its good work hardening capacity. The applications range from castings for hard crushing to bulletproof objects.
  • the valuable properties of high manganese steel result from the combination of the properties mentioned above, namely work hardening and ductility. Strain hardening occurs whenever high manganese steel is subjected to mechanical stress e.g. B. is exposed by impact or shock, which partially converts the austenite in the surface zone to an e-martensite. Strain hardening measurements show an increase in hardness of 200 - 550 HB.
  • the steel is essentially austenitic and work hardenable over its entire cross-section, there are great differences in its mechanical properties, in particular ductility, due to these structural differences.
  • Manganese steels usually have a carbon content of 0.7 to 1.7% by weight, with a manganese content between 5 and 18% by weight.
  • a carbon-manganese ratio between 1: 4 and 1:14 is also important if the properties of the manganese steels are to be retained. At lower ratios, there is no longer any austenitic steel, the steel can no longer be work hardened and the toughness is also impaired. The austenite is too stable at higher ratios; cold work hardening is not possible here either and the desired properties cannot be achieved either.
  • a phosphorus content of more than 0.1% by weight leads to a strong reduction in toughness, so that, as is known, a particularly low phosphorus content is desirable.
  • ASTM A 128/64 describes four different types of manganese steel with carbon contents between 0.7 and 1.45% by weight and manganese contents between 11 and 14% by weight.
  • the carbon content varies to change the degree of work hardening; this can also be influenced by the addition of chromium in amounts of 1.5 to 2.5% by weight. Large carbide deposits can be avoided by adding molybdenum up to 2.5% by weight.
  • a nickel addition of max. 4.0% by weight is said to stabilize the austenite, thereby avoiding the formation of pearlite in thick-walled castings.
  • manganese steel with approximately 5% by weight manganese is known. Although these steels are low in toughness, they are wear-resistant.
  • the object of the invention is to provide a method for producing hard manganese steel, wherein such a structure of the casting and the part made therefrom is achieved, so that on the one hand good mechanical properties, such as tensile strength and elongation at break, are guaranteed, while the work hardening is optimized , and on the other hand, temperature control of the melt is permitted such that the greatest possible output can be achieved.
  • Another object of the present invention is to match the level of properties between the edge and core zones as much as possible, since the stability of such a cast is also borne by the core zone, since this is also subject to strong mechanical or abrasive stresses during material removal.
  • the carbon-manganese ratio is between 1: 4 and 1:14 and the content of microalloying elements in% by weight titanium is more than 0.05 to 0.09, vanadium 0 to 0, 05, remainder iron and melting-related impurities, an insert being melted in an electric furnace, after which calcareous slag-forming additives are added to the liquid melt, the desired composition is adjusted and brought to a tapping temperature of 1450 to 1600 ° C., deoxidized with an oxygen-affine element , and is tapped into the ladle, and the content of microalloying elements is adjusted in the ladle, the melt being poured at a temperature between 1420 and 1520 ° C, consists essentially in the addition of manganese or manganese alloy in two steps takes place, the second addition of 5 to 25 wt .-% of the total addition of manganese or manganese alloy at a temperature of the melt takes place below 1520 ° C and the melt temperature is kept below this temperature until casting.
  • Example 1 is to be regarded as a comparative example because the process described therein represents the prior art.
  • the melt was covered with a slag consisting of 90% by weight limestone and 10% by weight calcium fluoride; then the melt was brought to a tapping temperature of 1520 ° C. The final deoxidation was then carried out with metallic aluminum. After deoxidation, the melt was poured into the ladle, where the temperature was measured at 1460 ° C. The melt was poured into a basic sand mold (magnesite). The casting obtained was a Turas with a gross weight of 14 t and a net weight of 11 t; its walls were between 60 and 180 mm thick.
  • the casting was allowed to cool to room temperature, removed from the mold and then slowly warmed again to 1050 ° C. After a four hour hold, the Turas was quenched in water.
  • the casting obtained in this way showed cracks that had to be sealed with a material of the same type by welding.
  • the tensile strength was 623 N / mm 2 (the test results from the transcrystalline material are given in the table).
  • Titanium (the content in the casting was 0.07% by weight) was added. The temperature of the melt was always kept below 1490 ° C. Round bars with a diameter of 110 mm were then cast at a casting temperature of 1460 ° C. After cooling, the bars were removed from the molds, heated to 1030 ° C and then held at this temperature for five hours.
  • the oven temperature was then lowered to 980 ° C and held at that level for 1 1/2 hours.
  • the bars were then quenched in a water bath.
  • Example 5 500 kg of manganese steel with the composition as in Example 5 was melted by the same procedure as in Example 5, except that vanadium was added to the ladle and not to the induction furnace.
  • the grain size of vanadium was 1/8 to 1/4 inch. (3.10 mm to 6.35 mm)
  • the following table shows the values of tensile strength and elongation at break for samples from the center and for those from the edge area according to the examples.

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Description

Die Erfindung bezieht sich auf einen kaltverfestigenden austenitischen Manganstahl (Hadfield Stahl) mit einer Bruchdehnung von 10 - 80 % und auf ein Verfahren zur Herstellung.The invention relates to a strain-hardening austenitic manganese steel (Hadfield steel) with an elongation at break of 10 - 80% and to a method for the production.

Kaltverfestigende austenitische Manganstähle haben in Form von Gußstücken, Schmiedestücken und Walzprodukten ein großes Anwendungsgebiet. Dieses große Anwendungsgebiet ergibt sich vor allem durch ihre eigene hohe Duktilität und ihr gutes Kaltverfestigungsvermögen. Die Anwendungen reichen von Gußstücken für Hartzerkleinerung bis zu kugelsicheren Gegenständen. Die wertvollen Eigenschaften von Manganhartstahl ergeben sich durch die Kombination der oben erwähnten Eigenschaften, nämlich Kaltverfestigungsvermögen und Duktilität. Kaltverfestigung tritt ein, wann immer Manganhartstahl einer mechanischen Beanspruchung z. B. durch Stoß oder Schlag ausgesetzt wird, welche den Austenit in der Oberflächenzone teilweise zu einem e-Martensit umwandelt. Messungen der Kaltverfestigung lassen eine Härtezunahme von 200 - 550 HB erkennen.Cold-hardening austenitic manganese steels have a large area of application in the form of castings, forgings and rolled products. This large area of application results above all from its own high ductility and its good work hardening capacity. The applications range from castings for hard crushing to bulletproof objects. The valuable properties of high manganese steel result from the combination of the properties mentioned above, namely work hardening and ductility. Strain hardening occurs whenever high manganese steel is subjected to mechanical stress e.g. B. is exposed by impact or shock, which partially converts the austenite in the surface zone to an e-martensite. Strain hardening measurements show an increase in hardness of 200 - 550 HB.

Somit nimmt die Härte der Gußstücke, Schmiedestücke und dergleichen im Laufe der Verwendung zu, wenn sie mechanisch beansprucht werden.Thus, the hardness of the castings, forgings and the like increases in use as they are mechanically stressed.

Da jedoch solche Teile auch einem Verschleiß durch Reibung ausgesetzt sind, wird die Oberflächenschicht ständig abgetragen, wobei Austenit an die Oberfläche gerät. Dieser Austenit wird durch neuerliche mechanische Beanspruchung wieder umgewandelt. Die Legierung, die sich unter der Oberflächenzone befindet, ist sehr duktil, und Manganhartstähle können daher eine hohe mechanische Schlagbeanspruchung aushalten, ohne daß eine Bruchgefahr besteht, sogar im Falle von dünnwandigen Teilen.However, since such parts are also subject to wear due to friction, the surface layer is constantly removed, with austenite reaching the surface. This austenite is converted again by renewed mechanical stress. The alloy located under the surface zone is very ductile, and manganese steels can therefore withstand high mechanical impact without risk of breakage, even in the case of thin-walled parts.

Im Falle von aus Manganhartstahl gefertigten Teilen ist es wichtig, daß eine Vorform oder ein Blockgußstück erzeugt wird, um die Eigenschaften der daraus gefertigten Teile im voraus zu bestimmen. Wenn das Gußstück ein unzulässig grobes Gefüge aufweist, wird der Teil eine geringe Duktilität haben. Bei großen Gußstücken weiß man, daß die Korngröße über den Querschnitt variiert. An der Außenseite findet man eine schmale verhältnismäßig feinkörnige Randzone, die von einem aus groben Stengelkristallen bestehenden Bereich und dann von dem kugeligen Gefüge im Zentrum des Gußstückes gefolgt wird.In the case of parts made from high manganese steel, it is important that a preform or ingot be made to determine the properties of the parts made therefrom. If the casting has an impermissibly coarse structure, the part will have a low ductility. With large castings it is known that the grain size varies across the cross-section. On the outside there is a narrow, relatively fine-grained edge zone, which is followed by an area consisting of coarse stem crystals and then by the spherical structure in the center of the casting.

Obwohl der Stahl über seinen gesamten Querschnitt im wesentlichen austenitisch und kaltverfestigbar ist, ergeben sich große Unterschiede bei seinen mechanischen Eigenschaften, insbesondere Duktilität, auf Grund dieser Gefügeunterschiede.Although the steel is essentially austenitic and work hardenable over its entire cross-section, there are great differences in its mechanical properties, in particular ductility, due to these structural differences.

Um eine möglichst gleichmäßige Duktilität über den gesamten Querschnitt zu erreichen, ist bereits vorgeschlagen worden, die Gießtemperatur so niedrig wie möglich zu halten, z. B. bei 1410°C, da ein zunehmendes Unterkühlen das Wachstum der Keime bewirken und ein feinerkörniges Gefüge erzeugen sollte. Diese niedrigen Gießtemperaturen werfen jedoch große Produktionsprobleme auf, z. B. entstehen Spannungsrisse im Gußstück und die rheologischen Eigenschaften des schmelzflüssigen Metalls sind solcherart, daß die Form nicht mehr genau gefüllt wird, insbesondere an den Kanten. Weiters erstarrt das schmelzflüssige Metall während des Gießens an der Auskleidung der Pfanne, was zu Pfannenresten oder Gußhäuten führt, die entfernt und neuerlich verarbeitet werden müssen. Während des eigentlichen Gießvorganges kann der Stopfen in der Auslaßöffnung stecken bleiben, was eine Unterbrechung des Gießens mit sich bringt. Aus dem Vorhergesagten ist leicht zu erkennen, daß die wirtschaftlichen Nachteile, die man für eine nichtreproduzierbare Kornverfeinerung auf sich nehmen müßte, so schwerwiegend sind, daß dieses Niedertemperaturgießverfahren nicht akzeptiert werden konnte.In order to achieve a ductility as uniform as possible over the entire cross section, it has already been proposed to keep the casting temperature as low as possible, e.g. B. at 1410 ° C, since increasing supercooling should cause the growth of the germs and should produce a fine-grained structure. However, these low casting temperatures pose major production problems, e.g. B. stress cracks arise in the casting and the rheological properties of the molten metal are such that the shape is no longer filled precisely, especially at the edges. Furthermore, the molten metal solidifies on the lining of the pan during casting, which leads to pan residues or cast skins that have to be removed and processed again. During the actual pouring process, the stopper can get stuck in the outlet opening, which leads to an interruption in the pouring. It is easy to see from the foregoing that the economic disadvantages that would have to be taken for a non-reproducible grain refinement are so severe that this low-temperature casting process could not be accepted.

Aus diesen Gründen sind bereits Versuche dahingehend unternommen worden, eine Kornverfeinerung durch Zusatz von weiteren Legierungselementen, z. B. Chrom, Titan, Zirkon und Stickstoff, in Mengen von mindestens 0,1 bis 0,2 Gew.-% zu erzielen. Obwohl diese Zusätze bei niedrigen Gießtemperaturen eine Kornverfeinerung bewirken, beeinträchtigen sie ziemlich stark die mechanischen Eigenschaften, vor allem die Dehnung und die Kerbschlagzähigkeit.For these reasons, attempts have already been made to refine the grain by adding further alloying elements, e.g. B. chromium, titanium, zirconium and nitrogen, in amounts of at least 0.1 to 0.2 wt .-%. Although these additives result in grain refinement at low casting temperatures, they have a considerable impact on the mechanical properties, especially the elongation and the impact strength.

Manganhartstähle (Hadfield Stähle) haben gewöhnlich einen Kohlenstoffgehalt von 0,7 bis 1,7 Gew.-%, bei einem Mangangehalt zwischen 5 und 18 Gew.-%. Ein Kohlenstoff-Mangan-Verhältnis zwischen 1 : 4 und 1 : 14 ist ebenfalls wichtig, wenn die Eigenschaften der Manganhartstähle beibehalten werden sollen. Bei kleineren Verhältnissen liegt kein austenitischer Stahl mehr vor, der Stahl kann nicht mehr kaltverfestigt werden und die Zähigkeit ist ebenfalls beeinträchtigt. Bei höheren Verhältnissen ist der Austenit zu stabil; auch hier ist keine Kaltverfestigung möglich und die gewünschten Eigenschaften können ebenfalls nicht erreicht werden.Manganese steels (Hadfield steels) usually have a carbon content of 0.7 to 1.7% by weight, with a manganese content between 5 and 18% by weight. A carbon-manganese ratio between 1: 4 and 1:14 is also important if the properties of the manganese steels are to be retained. At lower ratios, there is no longer any austenitic steel, the steel can no longer be work hardened and the toughness is also impaired. The austenite is too stable at higher ratios; cold work hardening is not possible here either and the desired properties cannot be achieved either.

Ein Phosphorgehalt über 0,1 Gew.-% führt zu einer starken Reduzierung der Zähigkeit, sodaß, wie man weiß, ein besonders niedriger Phosphorgehalt anzustreben ist.A phosphorus content of more than 0.1% by weight leads to a strong reduction in toughness, so that, as is known, a particularly low phosphorus content is desirable.

ASTM A 128/64 beschreibt vier verschiedene Manganhartstahlarten mit Kohlenstoffgehalten zwischen 0,7 und 1,45 Gew.-% und Mangangehalten zwischen 11 und 14 Gew.-%. Der Kohlenstoffgehalt variiert zwecks Änderung des Kaltverfestigungsgrades; diese kann auch durch den Zusatz von Chrom in Mengen von 1,5 bis 2,5 Gew.-% beeinflußt werden. Große Karbidausscheidungen können durch den Zusatz von Molybdän bis zu 2,5 Gew.-% vermieden werden. Ein Nickelzusatz von max. 4,0 Gew.-% soll den Austenit stabilisieren, wodurch die Bildung von Perlit in dickwandigen Gußstücken vermieden wird.ASTM A 128/64 describes four different types of manganese steel with carbon contents between 0.7 and 1.45% by weight and manganese contents between 11 and 14% by weight. The carbon content varies to change the degree of work hardening; this can also be influenced by the addition of chromium in amounts of 1.5 to 2.5% by weight. Large carbide deposits can be avoided by adding molybdenum up to 2.5% by weight. A nickel addition of max. 4.0% by weight is said to stabilize the austenite, thereby avoiding the formation of pearlite in thick-walled castings.

Weiters ist ein Manganhartstahl mit ungefähr 5 Gew.-% Mangan bekannt. Obwohl diese Stähle eine geringe Zähigkeit aufweisen, sind sie verschleißfest.Furthermore, a manganese steel with approximately 5% by weight manganese is known. Although these steels are low in toughness, they are wear-resistant.

Aus EP-A- 143 873 ist ein austenitischer Manganhartstahl und Verfahren zu seiner Herstellung bekannt geworden, wobei die Mikrolegierungszusätze Vanadin und Titan bewirken sollen, daß eine Kornfeinung über den gesamten Querschnitt auch großer Stücke aus dem Manganhartstahl erreicht wird, ohne dessen mechanische Eigenschaften, insbesondere Zähigkeit, zu verschlechtern. Im Zuge der Stahlerschmelzung in metallurgischen Öfen treten jedoch zumindest in den Bereichen der Energieeinbringung hohe Schmelzentemperaturen auf. Hohe Schmelzentemperaturen führen jedoch zum Unwirksamwerden der Desoxidations- und Mikrolegierungszusätze, sodaß der Manganhartstahl grob und gegebenenfalls stengelig kristallisiert, wodurch ein ungleiches Eigenschaftsniveau zwischen Rand und Kern des Gußstückes verursacht wird.From EP-A-143 873 an austenitic manganese steel and process for its production have become known, the microalloy additives vanadium and titanium being said to achieve grain refinement over the entire cross-section of large pieces of manganese steel without it mechanical properties, especially toughness, deteriorate. In the course of steel melting in metallurgical furnaces, however, high melt temperatures occur at least in the areas of energy input. However, high melt temperatures lead to the ineffectiveness of the deoxidation and microalloying additives, so that the manganese high-carbon steel crystallizes coarsely and, if necessary, stalkily, which causes an uneven level of properties between the edge and core of the casting.

Die Aufgabe der Erfindung besteht darin, ein Verfahren zur Erzeugung von Hartmanganstahl zu schaffen, wobei ein derartiges Gefüge des Gußstückes sowie des daraus gefertigten Teiles erreicht wird, sodaß einerseits gute mechanische Eigenschaften, wie Zugfestigkeit und Bruchdehnung, gewährleistet sind, wobei gleichzeitig die Kaltverfestigung optimiert ist, und andererseits eine Temperaturführung der Schmelze so erlaubt, daß ein möglichst großes Ausbringen erreichbar ist. Ein weiteres Ziel der vorliegenden Erfindung besteht darin, das Eigenschaftsniveau zwischen den Rand- und Kernzonen möglichst anzugleichen, da die Standfestigkeit eines derartigen Gusses auch von der Kernzone mitgetragen wird, da diese im Laufe der Materialabtragung ebenfalls starken mechanischen bzw. abrasiven Beanspruchungen unterliegt.The object of the invention is to provide a method for producing hard manganese steel, wherein such a structure of the casting and the part made therefrom is achieved, so that on the one hand good mechanical properties, such as tensile strength and elongation at break, are guaranteed, while the work hardening is optimized , and on the other hand, temperature control of the melt is permitted such that the greatest possible output can be achieved. Another object of the present invention is to match the level of properties between the edge and core zones as much as possible, since the stability of such a cast is also borne by the core zone, since this is also subject to strong mechanical or abrasive stresses during material removal.

Das erfindungsgemäße Verfahren zur Herstellung eines an sich bekannten kaltverfestigenden austenitischen Manganstahles mit einer Bruchdehnung zwischen 10 % und 80 % gemessen nach L = 5 d oder L = 10 d mit einem Gehalt in Gew.-% von Kohlenstoff 0,7 bis 1,7, Mangan 5,0 bis 18,0, Chrom 0 bis 3,0, Nickel 0 bis 4,0, Molybdän 0 bis 2,5, Silizium 0,1 bis 0,9, gegebenenfalls Zirkon 0,01 bis 0,05 und Phosphor max. 0,1, mit der Maßgabe, daß das Kohlenstoff-Mangan-Verhältnis zwischen 1 : 4 und 1 : 14 liegt und der Gehalt an Mikrolegierungselementen in Gew.-% Titan mehr als 0,05 bis 0,09, Vanadin 0 bis 0,05, Rest Eisen und erschmelzungsbedingte Verunreinigungen, wobei in einem Elektroofen ein Einsatz eingeschmolzen wird, wonach auf die flüssige Schmelze kalkhältige schlackebildende Zuschlagstoffe aufgegeben werden, die gewünschte Zusammensetzung eingestellt und auf eine Abstichtemperatur von 1450 bis 1600°C gebracht wird, mit einem sauerstoffaffinen Element desoxidiert, und in die Gießpfanne abgestochen wird, und in der Gießpfanne der Gehalt an Mikrolegierungselementen eingestellt wird, wobei die Schmelze bei einer Temperatur zwischen 1420 und 1520°C gegossen wird, besteht im wesentlichen darin, daß die Zugabe von Mangan oder von Manganlegierung in zwei Schritten erfolgt, wobei die zweite Zugabe von 5 bis 25 Gew.-% der gesamten Zugabe an Mangan oder Manganlegierung bei einer Temperatur der Schmelze unter 1520°C erfolgt und die Schmelzentemperatur bis zum Gießen unter dieser Temperatur gehalten wird.The process according to the invention for the production of a known cold-hardening austenitic manganese steel with an elongation at break between 10% and 80% measured according to L = 5 d or L = 10 d with a content in% by weight of carbon 0.7 to 1.7. Manganese 5.0 to 18.0, chromium 0 to 3.0, nickel 0 to 4.0, molybdenum 0 to 2.5, silicon 0.1 to 0.9, optionally zircon 0.01 to 0.05 and phosphorus Max. 0.1, with the proviso that the carbon-manganese ratio is between 1: 4 and 1:14 and the content of microalloying elements in% by weight titanium is more than 0.05 to 0.09, vanadium 0 to 0, 05, remainder iron and melting-related impurities, an insert being melted in an electric furnace, after which calcareous slag-forming additives are added to the liquid melt, the desired composition is adjusted and brought to a tapping temperature of 1450 to 1600 ° C., deoxidized with an oxygen-affine element , and is tapped into the ladle, and the content of microalloying elements is adjusted in the ladle, the melt being poured at a temperature between 1420 and 1520 ° C, consists essentially in the addition of manganese or manganese alloy in two steps takes place, the second addition of 5 to 25 wt .-% of the total addition of manganese or manganese alloy at a temperature of the melt takes place below 1520 ° C and the melt temperature is kept below this temperature until casting.

Es war durchaus überraschend, daß durch die schrittweise Zugabe des Mangans unter Einhaltung einer bestimmten Temperaturgrenze das Eigenschaftsniveau, wie angestrebt, erhalten bzw. sogar verbessert werden kann, wobei gleichzeitig ein zu niedriges Ausbringen der Legierung vermieden wird. Obwohl keine vollkommen gesicherten Ergebnisse vorliegen, kann unter Umständen angenommen werden, daß bei Einhaltung einer bestimmten Temperaturgrenze Kristallisationskeime von der Manganlegierung in der Schmelze erhalten bleiben, die in späterer Folge zwar für eine bestimmte Struktur des Gusses Sorge tragen, wobei jegliche zusätzliche Verschlechterung des Eigenschaftsniveaus durch andere Legierungselemente vermieden werden kann.It was quite surprising that by gradually adding the manganese while maintaining a certain temperature limit, the level of properties as desired can be maintained or even improved, while at the same time preventing the alloy from being applied too low. Although no completely reliable results are available, it can be assumed under certain circumstances that if a certain temperature limit is observed, nuclei from the manganese alloy remain in the melt, which will subsequently ensure a certain structure of the casting, with any additional deterioration in the property level other alloying elements can be avoided.

Im folgenden wird die Erfindung anhand der Beispiele näher erläutert.The invention is explained in more detail below with the aid of the examples.

Beispiel 1:Example 1:

Das Beispiel 1 ist als Vergleichsbeispiel zu werten, weil das darin beschriebene Verfahren den Stand der Technik darstellt.Example 1 is to be regarded as a comparative example because the process described therein represents the prior art.

15 t Manganstahl mit der folgenden Zusammensetzung in Gew.-% wurden in einem Lichtbogenofen erschmolzen: 1,21 Kohlenstoff, 12,3 Mangan, 0,47 Silizium, 0,023 Phosphor, 0,45 Chrom und Spuren von Nickel und Molybdän.15 tons of manganese steel with the following composition in% by weight were melted in an arc furnace: 1.21 carbon, 12.3 manganese, 0.47 silicon, 0.023 phosphorus, 0.45 chromium and traces of nickel and molybdenum.

Die Schmelze wurde mit einer aus 90 Gew.-% Kalkstein und 10 Gew.-% Kalziumfluorid bestehenden Schlacke bedeckt; danach wurde die Schmelze auf eine Abstichtemperatur von 1520°C gebracht. Das abschließende Desoxidieren erfolgte dann mit metallischem Aluminium. Nach der Desoxidation wurde die Schmelze in die Gießpfanne abgegossen, wo die Temperatur mit 1460° C gemessen wurde. Die Schmelze wurde in eine basische Sandform (Magnesit) gegossen. Das erhaltene Gußstück war ein Turas mit einem Bruttogewicht von 14 t und einem Nettogewicht von 11 t; seine Wände waren zwischen 60 und 180 mm dick.The melt was covered with a slag consisting of 90% by weight limestone and 10% by weight calcium fluoride; then the melt was brought to a tapping temperature of 1520 ° C. The final deoxidation was then carried out with metallic aluminum. After deoxidation, the melt was poured into the ladle, where the temperature was measured at 1460 ° C. The melt was poured into a basic sand mold (magnesite). The casting obtained was a Turas with a gross weight of 14 t and a net weight of 11 t; its walls were between 60 and 180 mm thick.

Das Gußstück wurde auf Raumtemperatur abkühlen gelassen, aus der Form genommen und dann neuerlich langsam auf 1050°C erwärmt. Nach einer Haltezeit von vier Stunden wurde der Turas in Wasser abgeschreckt. Das auf diese Art erhaltene Gußstück wies Risse auf, die mittels Schweißens mit einem artgleichen Material verschlossen werden mußten. Die metallographischen Prüfungen ließen eine ausgeprägte transkristalline Zone mit einer anschließenden kugeligen Gefügezone erkennen. Prüfstücke aus der besagten kugeligen Zone wiesen eine Dehnung von 8,4 % auf, gemessen gemäß L = 10 d. Die Zugfestigkeit betrug 623 N/mm2 (Die Prüfergebnisse aus dem transkristallinen Material sind in der Tabelle angegeben).The casting was allowed to cool to room temperature, removed from the mold and then slowly warmed again to 1050 ° C. After a four hour hold, the Turas was quenched in water. The casting obtained in this way showed cracks that had to be sealed with a material of the same type by welding. The metallographic tests revealed a pronounced transcrystalline zone with a subsequent spherical structure zone. Test pieces from said spherical zone had an elongation of 8.4%, measured according to L = 10 d. The tensile strength was 623 N / mm 2 (the test results from the transcrystalline material are given in the table).

Beispiel 2:Example 2:

500 kg Manganstahl folgender Zusammensetzung in Gew.-% wurden in einem Induktionsofen erschmolzen: 1,24 Kohlenstoff, 0,52 Silizium, 12,57 Mangan, 0,13 Nickel, 0,42 Chrom, 0,027 Phosphor und 0,008 Schwefel.500 kg of manganese steel of the following composition in% by weight were melted in an induction furnace: 1.24 carbon, 0.52 silicon, 12.57 manganese, 0.13 nickel, 0.42 chromium, 0.027 phosphorus and 0.008 sulfur.

Zunächst wurden jedoch nur 90 Gew.-% des erforderlichen Mangangehaltes in den Ofen hinzugefügt und die Schmelze wurde auf eine Temperatur von 1620°C gebracht. Danach wurde die Schmelze auf eine Temperatur von 1520°C mittels Argonspülung abgekühlt und die verbleibenden 10 Gew.-% des Gesamtmangangehaltes wurden hinzugefügt. Die Schmelze wurde mit Schlacke bedeckt und auf eine Abstichtemperatur von 1470° C gebracht. Zwecks abschließender Desoxidation wurde metallisches Aluminium hinzugefügt und danach erfolgte eine Zugabe von 0,04 Gew.-% Vanadium in die Schmelze, dies entsprach einem Gehalt von 0,035 Gew.-% Vanadium im Gußstück. Die Schmelze wurde dann in die Gießpfanne abgegossen und 0,08 Gew.-%First, however, only 90% by weight of the required manganese content was added to the furnace and the melt was brought to a temperature of 1620 ° C. The melt was then cooled to a temperature of 1520 ° C. by means of argon purging and the remaining 10% by weight of the total manganese content was added. The melt was covered with slag and brought to a tapping temperature of 1470 ° C. Metallic aluminum was added for the final deoxidation and then 0.04% by weight of vanadium was added to the melt, corresponding to a content of 0.035% by weight of vanadium in the casting. The melt was then poured into the ladle and 0.08% by weight

Titan (der Gehalt im Gußstück betrug 0,07 Gew.-%) wurden hinzugefügt. Die Temperatur der Schmelze wurde immer unter 1490°C gehalten. Rundstäbe mit einem Durchmesser von 110 mm wurden dann bei einer Gießtemperatur von 1460° C gegossen. Nach dem Abkühlen wurden die Stäbe aus den Formen genommen, auf 1030°C erwärmt und dann fünf Stunden bei dieser Temperatur gehalten.Titanium (the content in the casting was 0.07% by weight) was added. The temperature of the melt was always kept below 1490 ° C. Round bars with a diameter of 110 mm were then cast at a casting temperature of 1460 ° C. After cooling, the bars were removed from the molds, heated to 1030 ° C and then held at this temperature for five hours.

Die Öfentemperatur wurde dann auf 980°C abgesenkt und 1 1/2 Stunden auf diesem Niveau gehalten. Die Stäbe wurden dann in einem Wasserbad abgeschreckt.The oven temperature was then lowered to 980 ° C and held at that level for 1 1/2 hours. The bars were then quenched in a water bath.

Beispiel 3:Example 3:

500 kg Manganstahl mit der Zusammensetzung wie in Beispiel 5 wurden nach demselben Verfahren wie in Beispiel 5 erschmolzen, außer daß Vanadium in die Gießpfanne und nicht in den Induktionsofen beigegeben wurde. Die Korngröße von Vanadium betrug 1/8 bis 1/4 Zoll. (3,10 mm bis 6,35 mm)500 kg of manganese steel with the composition as in Example 5 was melted by the same procedure as in Example 5, except that vanadium was added to the ladle and not to the induction furnace. The grain size of vanadium was 1/8 to 1/4 inch. (3.10 mm to 6.35 mm)

In der folgenden Tabelle werden die Werte der Zugfestigkeit und Bruchdehnung für Proben vom Zentrum und für solche vom Randbereich gemäß den Beispielen angegeben.The following table shows the values of tensile strength and elongation at break for samples from the center and for those from the edge area according to the examples.

Figure imgb0001
Bei dem Einsatz von Gußstücken, die einen geringeren Titangehalt aufwiesen, hat sich ergeben, daß die Standfestigkeit wahrscheinlich aufgrund der schlechteren Abriebeigenschaft schlechter ist, als bei dem erfindungsgemäßen Titangehalt.
Figure imgb0001
When using castings with a lower titanium content, it has been found that the stability is probably worse than with the titanium content according to the invention due to the poorer abrasion properties.

Claims (4)

1. Process for the manufacture of a strain-hardening austenitic manganese steel known per se, with a break elongation between 10 % and 80 % measured according to L = 5 d or L = 10 d with a content in % by weight of carbon 0.7 to 1.7, manganese 5.0 to 18.0, chromium 0 to 3.0, nickel 0 to 4.0, molybdenum 0 to 2.5, silicon 0.1 to 0.9, possibly zirkonium 0.01 to 0.05, phosphorus max. 0.1, possibly 0.01 to 0.05 % aluminium, provided that the carbon manganese ratio is between 1 : 4 and 1 : 14 and the content of micro-alloy elements in % by weight titanium more than 0.05 to 0.09, vanadium 0 to 0.5, the rest iron and melt-dependent contaminants ; whereby in an electric furnace a charge is melted, after which calcareous slag-forming additives are added to the liquid melt, the desired composition is adjusted and brought to a tapping temperature of 1450 to 1600°C, de-oxidised with an element having an affinity for oxygen and tapped into the pouring ladle, and in the pouring ladle the content of micro-alloy elements is adjusted, whereby the melt is poured at a temperature between 1420 and 1520°C, characterised in that the addition of manganese or of manganese alloy takes place in two steps, whereby the second addition of 5 to 25 % by weight of the total addition of manganese or manganese alloy takes place at a temperature of the melt below 1520°C, and the melting temperature is kept below this temperature up to pouring.
2. Process according to Claim 1, characterised in that the second addition of manganese or manganese alloy is made with ferromanganese, and in that 7 to 15 % by weight of the overall addition of manganese or of manganese alloy takes place at a temperature of the melt below 1520° C and the melting temperature is kept below this temperature up to pouring.
3. Process according to Claims 1 and 2, characterised in that titanium is added to the pouring ladle in the form of ferrotitanium.
4. Process according to Claims 1 to 3, characterised in that the zirkonium content of the steel is between 0.01 and 0.05 % by weight.
EP84890187A 1983-10-14 1984-10-11 Hadfield type manganese steel and process for the manufacture thereof Expired EP0141804B1 (en)

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AT390806B (en) * 1983-09-23 1990-07-10 Kos Bernd AUSTENITIC MANGANIC STEEL AND METHOD FOR THE PRODUCTION THEREOF
FR2795754B1 (en) * 1999-07-02 2004-10-08 Thyssen Schienen Technik Gmbh STEEL RAILWAY RAIL HAVING IMPROVED CHARACTERISTICS, IN PARTICULAR NEEDLE POINT RAIL, AND METHOD FOR MANUFACTURING SUCH A RAIL
US6572713B2 (en) * 2000-10-19 2003-06-03 The Frog Switch And Manufacturing Company Grain-refined austenitic manganese steel casting having microadditions of vanadium and titanium and method of manufacturing
KR100852497B1 (en) * 2007-03-12 2008-08-18 한양대학교 산학협력단 Fe based alloy having corrosion resistance and abrasion resistance and preparation method thereof
TWI450973B (en) * 2011-05-19 2014-09-01 China Steel Corp Steel making process
CN103498108A (en) * 2013-10-22 2014-01-08 江苏盛伟模具材料有限公司 High-boron high-chromium low-carbon wear-resisting alloy steel with good red hardness and manufacturing method thereof
CN103572166A (en) * 2013-10-22 2014-02-12 江苏盛伟模具材料有限公司 Boracic high-speed steel with good red hardness and preparation method thereof
CN103498107A (en) * 2013-10-22 2014-01-08 江苏盛伟模具材料有限公司 High-boron high-chromium low-carbon high-temperature-resistant wear-resisting alloy steel and manufacturing method thereof
CN103540855A (en) * 2013-10-25 2014-01-29 丁家伟 High-toughness high-boron medium-chrome low-carbon wear-resisting alloy steel and preparation method thereof
KR102145761B1 (en) * 2019-01-03 2020-08-19 (주)영신특수강 High manganese casting alloy steel for crusher and manufacturing method thereof
CN113088809B (en) * 2021-02-26 2022-04-05 舞阳钢铁有限责任公司 BTW wear-resistant steel plate and production method thereof
CN113444985B (en) * 2021-05-24 2022-10-21 北京中永业科技有限公司 Steel material and preparation method thereof

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