EP0312068A1 - Procédé pour la nitruration de la fonte - Google Patents

Procédé pour la nitruration de la fonte Download PDF

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Publication number
EP0312068A1
EP0312068A1 EP88117062A EP88117062A EP0312068A1 EP 0312068 A1 EP0312068 A1 EP 0312068A1 EP 88117062 A EP88117062 A EP 88117062A EP 88117062 A EP88117062 A EP 88117062A EP 0312068 A1 EP0312068 A1 EP 0312068A1
Authority
EP
European Patent Office
Prior art keywords
cast iron
nitrogen
agent
weight
ppm
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP88117062A
Other languages
German (de)
English (en)
Inventor
Friedrich Wolfsgruber
Hartmut Dr. Meyer-Grünow
Detlef Dr. Missol
Jochem Richter
Julius Dr. Veit
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Halbergerhuette GmbH
Halbergerhutte GmbH
Evonik Operations GmbH
Original Assignee
Halbergerhuette GmbH
SKW Trostberg AG
Halbergerhutte GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Halbergerhuette GmbH, SKW Trostberg AG, Halbergerhutte GmbH filed Critical Halbergerhuette GmbH
Publication of EP0312068A1 publication Critical patent/EP0312068A1/fr
Ceased legal-status Critical Current

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Classifications

    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00Refining of pig-iron; Cast iron
    • C21C1/10Making spheroidal graphite cast-iron
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00Refining of pig-iron; Cast iron
    • C21C1/08Manufacture of cast-iron

Definitions

  • the invention relates to means for embroidering cast iron with lamellar graphite or spheroidal graphite and methods for introducing the agent into the cast iron melt.
  • the material grades of cast iron with lamellar graphite are standardized. They are based on the tensile strength of a test bar with a raw casting diameter of 30 mm.
  • the tensile strength is influenced by the graphite formation, the amount of graphite and the basic structure, which can have a pearlitic / ferritic to pearlitic structure.
  • the structure of the basic structure can be specifically influenced by adding alloying elements.
  • the pearlite structure is stabilized with increasing effectiveness by the elements manganese, chrome, copper and tin.
  • the addition of these elements to cast iron represents a significant cost factor (e.g. copper and tin) and can only be done up to certain upper limits for chrome and manganese.
  • alloying elements such as manganese and chromium increase the risk of ledeburitic solidification, so that they can only be used up to a maximum of 1 or 0.5% by weight without a negative effect on the machinability of the cast iron.
  • care must also be taken to ensure that the chromium content does not degrade even after repeated remelting.
  • copper This fact also places limits on the alloying of copper, although it enables pearlite stabilization without additional risk of ledeburitic solidification.
  • only relatively expensive high-purity copper may be used in order to exclude the harmful effects of trace elements that may be contained in the copper.
  • Chromium and copper alloyed circuit material has considerable disadvantages.
  • a very effective pearlite stabilization is achieved with tin, but the costs are significant. With this element, a fully pearlitic structure is achieved in all areas of the casting. A further addition of tin to a cast iron, which already has a fully pearlitic structure, no longer increases its tensile strength.
  • DE-OS 24 02 945 describes high-strength cast iron with spheroidal graphite and a process for its production. Nitriding to contents of 0.0035 to 0.02% by weight of N takes place by means of alloys containing N such as Fe-Mn-N and Fe-Cr-N or with hexamine.
  • the nitrogen supply and thus the nitrogen yield is relatively broad.
  • the nitrogen yield is very low, so that the alloys have to be added in relatively large amounts, which in turn has undesirable effects such as introducing a relatively large amount of foreign metal, increased slag accumulation and inadequate dissolving behavior of the nitrogen.
  • Hexamine as explosive explosive (Textbook of Organic Chemistry, Paul Karrer, 1963, p. 500) is dangerous.
  • the solubility equilibrium for nitrogen in cast iron is affected by the alloying elements and the temperature of the molten iron. In the usual temperature range of 1400 to 1550 ° C, the solubility equilibrium for nitrogen in technical cast iron alloys is 40 to 60 ppm. The consequence of this is that all nitrogen contents which are above the value of this solubility equilibrium are unstable. The nitrogen loss is usually 10 ppm per 30 minutes of melt life at 1480 ° C. A subsequent correction of the nitrogen content by adding further N-containing alloys is no longer possible due to the associated increase in the manganese or chromium values, since this would cause undesired ledeburitic solidification of the cast iron.
  • the object of the invention is therefore to provide a means and a method which permits simple, inexpensive pearlite stabilization or strength increase by working with a high nitrogen yield by increasing the pearlite content in cast iron with lamellar graphite or spheroidal graphite.
  • an agent for nitriding cast iron which is characterized in that it contains at least 50% by weight of nitrogen-containing compounds having an NCN structure or / and mixtures of calcium cyanamide with nitrides of silicon, ferrosilicon, manganese and chromium or consists of it.
  • nitrogen compounds give a high nitrogen yield without introducing undesirable alloy metals.
  • Advantageously used as nitrogen compounds are those with a high nitrogen content which are cheaply available on an industrial scale. This includes in particular cyanamide, dicyandiamide, guanidine, aminoguanidine, urea, hexamethylenetetramine, cyanuric acid, azulmic acid, melamine, melam, melem, melon, polymeric triazine compounds and guanamines, which are preferred.
  • nitrogen compounds preferred in the agent according to the invention have the property of disintegrating into gaseous products in the cast iron melt, as a result of which slag formation is avoided.
  • calcium cyanamide e.g. used in its technical form as calcium cyanamide and its mixtures with nitrides of silicon, ferrosilicon, manganese and chromium.
  • the agent according to the invention also contains additives which bring about an acceleration or deceleration of the reaction in the cast iron melt in an amount of 0.5 to 50% by weight and essentially consist of carbon, iron or / and silicon.
  • Suitable additives are flame carbon, ferrosilicon, iron, graphite, finely divided silica and silica-containing dusts, which can be used to optimize the nitrogen yield depending on the nitrogen compound used and the N requirement.
  • the agent preferably contains 10 to 35% by weight of one of the additives mentioned.
  • the nitriding can be carried out in the temperature range from 1200 to 1600 ° C.
  • composition of the agent at different temperatures is explained in more detail in the examples.
  • a mixture of about 97% by weight of urea and about 3% by weight of flame carbon is preferred (example 2).
  • urea is preferably used for nitriding (example 1), and at a temperature of 1460 ° C., for example, a mixture of 35% by weight of urea, 35% by weight of dicyandiamide and 30% by weight is used.
  • -% Ferrosilicon 75 added to the iron smelter (Example 3).
  • the amount of the agent is low. Depending on the type of agent, the form of application and the desired increase in strength, 0.1 to 6 kg of agent are used per ton of cast iron. An amount of 0.5 to 1 kg of the agent is preferably used in order to establish a nitrogen content of 50 to 200 ppm in lamellar graphite or spheroidal graphite cast iron.
  • the tensile strength (Rm) of this quality should be increased by embroidering the molten cast iron by 50 N / mm2 ( ⁇ Rm). Increasing the amount of nitrogen by 10 ppm free nitrogen improves the tensile strength by 7 N / mm2.
  • the nitrogen content of the untreated cast iron is 42 ppm.
  • the subsequently measured nitrogen concentration of 152 ppm in cast iron corresponds to a nitrogen yield of 32.5%.
  • the tensile strength measured on the 30 mm test bar, was increased from 260 to 315 N / mm 2.
  • the tensile strength was to be increased by 50 N / mm 2 as in Example 1.
  • a cored wire with a diameter of 13 mm is used, which contains a mixture of 97% by weight of urea and 3% by weight of flame carbon. Its filling weight is 120 g / m, the nitrogen content is 54 g / m.
  • the aim is to increase the tensile strength, measured on the test bar of 30 mm in diameter, by 50 N / mm2.
  • the nitrogen concentrations required to increase the tensile strength are calculated in accordance with Example 1 and give 41 ppm.
  • a 9 mm diameter cored wire is used to embroider the cast iron melt 35% by weight urea 35% by weight dicyandiamide 30% by weight FeSi 75 contains.
  • the fill weight of this wire is 34 g / m, the nitrogen content is 29 g / m.
  • the tensile strength measured on a 30 mm test bar, was increased from 210 to 264 N / mm2.
  • a 9 mm diameter cored wire is used to embroider the cast iron melt to this value 97% by weight of calcium cyanamide and 3% by weight flame coal contains.
  • the tensile strength measured on the 30 mm test bar, increased from 210 to 258 N / mm2.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
EP88117062A 1987-10-15 1988-10-13 Procédé pour la nitruration de la fonte Ceased EP0312068A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3734877 1987-10-15
DE3734877A DE3734877C1 (de) 1987-10-15 1987-10-15 Mittel und Verfahren zur Aufstickung von Gusseisen

Publications (1)

Publication Number Publication Date
EP0312068A1 true EP0312068A1 (fr) 1989-04-19

Family

ID=6338365

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88117062A Ceased EP0312068A1 (fr) 1987-10-15 1988-10-13 Procédé pour la nitruration de la fonte

Country Status (4)

Country Link
US (1) US4970051A (fr)
EP (1) EP0312068A1 (fr)
JP (1) JPH01136918A (fr)
DE (1) DE3734877C1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2458995C1 (ru) * 2011-03-10 2012-08-20 Владимир Константинович Афанасьев Способ обработки расплава чугуна

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9950966B2 (en) 2012-07-05 2018-04-24 Gestalt Chemical Products, Inc. Manufacturing of nitrogen-containing materials

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1225215B (de) * 1964-08-20 1966-09-22 Elektrometallurgie M B H Ges Verfahren zur Herstellung eines stickstoffhaltigen Stahlveredlers
US3322530A (en) * 1962-08-24 1967-05-30 Ishikawajima Harima Heavy Ind Method for adding additives to molten steel
BE791836A (fr) * 1972-11-23 1973-03-16 Centre Rech Metallurgique Procede pour la renitruration des aciers.
DE1608409B2 (de) * 1968-03-13 1975-08-07 Buderus'sche Eisenwerke, 6330 Wetzlar GuBeisenlegierung mit Stickstorfzusatz
BE840404A (fr) * 1976-04-05 1976-08-02 Procede de preparation d'elements pour la renitruration
DE2807930A1 (de) * 1978-02-24 1979-09-06 Maschf Augsburg Nuernberg Ag Verfahren zum giessen von werkstuecken, insbesondere von giesskokillen hoher temperaturwechselbestaendigkeit
EP0015662A1 (fr) * 1979-02-28 1980-09-17 International Harvester Company Procédé de traitement d'un bain de fonte dans une poche de coulée par un fil de magnésium entouré d'une gaine

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE13992C (de) * J. HtRD in Bishopston (England) Bogenabnehmer für Papiermaschinen
DE1229122B (de) * 1962-05-11 1966-11-24 Ishikawajima Harima Heavy Ind Verfahren zum Aufsticken von Stahlschmelzen
JPS543129B2 (fr) * 1973-01-24 1979-02-19
JPS5535461B2 (fr) * 1974-08-16 1980-09-13
US4560409A (en) * 1984-08-29 1985-12-24 Superior Graphite Metal bearing graphitic carbons
BR8606249A (pt) * 1985-12-17 1987-09-29 Sueddeutsche Kalkstickstoff Composicao finamente granulada para a dessulfuracao de ferro fundido e processo para sua preparacao

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3322530A (en) * 1962-08-24 1967-05-30 Ishikawajima Harima Heavy Ind Method for adding additives to molten steel
DE1225215B (de) * 1964-08-20 1966-09-22 Elektrometallurgie M B H Ges Verfahren zur Herstellung eines stickstoffhaltigen Stahlveredlers
DE1608409B2 (de) * 1968-03-13 1975-08-07 Buderus'sche Eisenwerke, 6330 Wetzlar GuBeisenlegierung mit Stickstorfzusatz
BE791836A (fr) * 1972-11-23 1973-03-16 Centre Rech Metallurgique Procede pour la renitruration des aciers.
BE840404A (fr) * 1976-04-05 1976-08-02 Procede de preparation d'elements pour la renitruration
DE2807930A1 (de) * 1978-02-24 1979-09-06 Maschf Augsburg Nuernberg Ag Verfahren zum giessen von werkstuecken, insbesondere von giesskokillen hoher temperaturwechselbestaendigkeit
EP0015662A1 (fr) * 1979-02-28 1980-09-17 International Harvester Company Procédé de traitement d'un bain de fonte dans une poche de coulée par un fil de magnésium entouré d'une gaine

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DEB-D13992, DEGUSSA, 26-08-1954 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2458995C1 (ru) * 2011-03-10 2012-08-20 Владимир Константинович Афанасьев Способ обработки расплава чугуна

Also Published As

Publication number Publication date
US4970051A (en) 1990-11-13
JPH01136918A (ja) 1989-05-30
DE3734877C1 (de) 1988-10-27

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