EP2749658A1 - Procédé de production de coulée de fonte ductile ausferritique - Google Patents

Procédé de production de coulée de fonte ductile ausferritique Download PDF

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Publication number
EP2749658A1
EP2749658A1 EP12382541.6A EP12382541A EP2749658A1 EP 2749658 A1 EP2749658 A1 EP 2749658A1 EP 12382541 A EP12382541 A EP 12382541A EP 2749658 A1 EP2749658 A1 EP 2749658A1
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EP
European Patent Office
Prior art keywords
casting
ausferritic
ductile iron
insulating material
cooling
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.)
Withdrawn
Application number
EP12382541.6A
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German (de)
English (en)
Inventor
Ramón Suarez Creo
Jon Garay Abascal
Urko de la Torre Ugarte
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.)
Thermal Quality Control Technologies SLU
Veigalan Estudio 2010 SLU
Casa Maristas Azterlan
Original Assignee
Thermal Quality Control Technologies SLU
Veigalan Estudio 2010 SLU
Casa Maristas Azterlan
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.)
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Publication date
Application filed by Thermal Quality Control Technologies SLU, Veigalan Estudio 2010 SLU, Casa Maristas Azterlan filed Critical Thermal Quality Control Technologies SLU
Priority to EP12382541.6A priority Critical patent/EP2749658A1/fr
Publication of EP2749658A1 publication Critical patent/EP2749658A1/fr
Withdrawn legal-status Critical Current

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    • 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
    • C21D5/00—Heat treatments of cast-iron
    • 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
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C21D1/20—Isothermal quenching, e.g. bainitic hardening
    • 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
    • C21D1/68—Temporary coatings or embedding materials applied before or during heat 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/68—Temporary coatings or embedding materials applied before or during heat treatment
    • C21D1/70—Temporary coatings or embedding materials applied before or during heat treatment while heating or quenching
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C37/00—Cast-iron alloys
    • C22C37/04—Cast-iron alloys containing spheroidal graphite

Definitions

  • the present invention is encompassed within the sector of metallurgical industry. Particularly, it relates to a new method for the manufacturing of ductile iron with a completely ausferritic matrix which has proved to be a more economical, simple and faster alternative method to the methods currently used.
  • Ausferritic ductile iron is a high strength, wear resistance, fatigue and rolling contact resistant material with good toughness that finds a wide variety of applications.
  • ausferritic ductile iron For the manufacturing of ausferritic ductile iron with high quality basically the most common and easiest to reproduce method consists in an austempering process.
  • the ausferritic ductile iron obtained accordingly is usually referred to as austempered ductile iron (ADI).
  • the austempering process is a three-step heat treatment which comprises the austenitization of the casting at a temperature higher than 850oC until the matrix structure attains a reasonably uniform carbon content; quenching to an intermediate temperature range of 260 to 400oC and austempering, which consists in the transformation to austenitic-ferritic structure at the isothermal temperature. This process is characterized mainly by its remarkable inherent cost, representing a large percentage of the total cost of cast parts.
  • the present invention relates to a method for the manufacturing of an ausferritic ductile iron alloy of high quality, at much lower production costs than the conventional methods of the state of the art without the necessity to use costly heat treatments and salt bath or electrical furnaces. Therefore, a significant reduction of energy, costs and production time is advantageously obtained.
  • an ausferritic ductile iron alloy of high quality means that it presents mechanical properties equal to those obtained for ADI by means of conventional treatment methods according to norm UNE-N 1564:2011 (see Example). Said ausferritic ductile iron alloy presents a completely ausferritic microstructure.
  • the method of the invention yields an ausferritic ductile iron alloy of high quality which contains the following typical alloying constituents for ductile iron: carbon, silicon and magnesium, and optionally one or more of the following elements: copper, nickel, manganese, molybdenum, the balance being iron and incidental impurities such as phosphorous, sulfur, etc.
  • the method of the invention yields an ausferritic ductile iron alloy that contains the following constituents: carbon, silicon, magnesium, copper, nickel, manganese and molybdenum the balance being iron and incidental impurities such as phosphorous, sulfur, etc.
  • the method of the invention yields an ausferritic ductile iron alloy that presents the following chemical composition (percentages expressed by weight with respect to the total weight of the ausferritic ductile iron alloy):
  • the method of the invention comprises the following steps:
  • the melt of the ductile iron alloy to be poured in the mould is prepared from conventional raw materials such as pig iron, steel, soft iron, graphite, ferroalloys, among others.
  • the raw materials are put in contact according to conventional methods which include steps such as mixing of components, melting, adjusting the alloy composition by adding further components, treatment with known magnesium containing compounds, and inoculation with known inoculating materials.
  • the melt thus required to prepare the ausferritic ductile iron alloy of any one of the above mentioned compositions can be easily prepared by the skilled person in the art.
  • the mould can be a metallic mould or a sand mould. Casting of the melt is done in any conventional manner.
  • the solidification of the casting and subsequent cooling in the mould until the casting temperature is between 800oC and 950oC is also carried out in a conventional manner. Shaking out the casting at said temperature between 800oC and 950oC is also carried out by means known in the art.
  • Step (iv) of cooling the casting until the temperature of the casting reaches a value between 275oC to 450oC can be carried out by air cooling, forced air cooling, quenching into any adequate quench medium such as oil, water, or mixtures of water and at least one polymer.
  • the way of cooling and the cooling means are conventional and are employed at room temperature.
  • the step (v) of introducing the casting in an insulating material and leaving the casting inside it, is carried out until a completely ausferritic microstructure is obtained.
  • introducing the casting in an insulating material means that the casting is completely surrounded or covered by the insulating material.
  • Insulating materials useful in the present invention are any material or combination of materials which retard the heat flow and have a low thermal conductivity.
  • any insulating material within which the casting temperature does not decrease below the martensite start formation temperature before the austenite transforms completely into ferrite needles and carbon enriched austenite can be used.
  • the insulating material presents a conductivity of equal or less than 1 W/mK, preferably equal or less than 0.5 W/mK, and more preferably equal or less than 0.08 W/mK.
  • Said materials may be in the solid or the liquid state. They can also be of different compositions (i.e. glass, ceramic, plastic) and different internal structure (i.e. cellular, fibrous).
  • insulating materials are: silica, rock wool, slag wool, glass fibers, foamed plastics such as polystyrene, polyurethane, polyisocyanurate, agricultural waste products such as rice husks; calcium silicate, expanded vermiculite, hereinafter also referred to as vermiculite, expanded perlite, hereinafter also referred to as perlite, cellulose and diatomaceous earth.
  • insulation materials can be used in the present method in a variety of suitable forms.
  • suitable forms are rigid or flexible boards, blocks, bricks, sheets, blankets, foams, loose fills, such as granulates, pellets or particles, and pre-formed shapes
  • Step (v) can be carried out in many different ways depending for instance on the size of the castings and the selected insulating material.
  • a container comprising the insulating material is used, in which case the casting is introduced therein and is completely surrounded or covered by the insulating material.
  • a container comprising insulating material in form of a loose fill is used; the casting is introduced therein, and is completely surrounded or covered by the loose fill of insulating material.
  • the austenite decomposes to ferrite needles and carbon enriched austenite.
  • This reaction thus must take place at a temperature above the martensite formation start temperature (M s ) to avoid formation of martensite in the casting. Because of this reason, and in order to obtain a completely ausferritic microstructure the insulating material maintains the temperature of the casting above (M s ).
  • the insulating material is in the form of a loose fill.
  • Loose fill can be particles, pellets, granulates, which may have different sizes and shapes.
  • expanded perlite which has a thermal conductivity of less than 0.059 W/mK, is used as insulating material.
  • expanded vermiculite is used.
  • the period of time during which the casting is leaved inside the insulating material can vary depending on factors such as the casting size. Castings are however to be left inside, at least until the austenite transforms completely into ferrite needles and carbon enriched austenite, which is stable at room temperature, that is until a completely ausferritic microstructure is achieved. In general said period is typically comprised between 30 and 120 minutes although greater and lesser durations are also foreseeable depending on each particular case. Said period can be easily determined in each case by the skilled person in the art.
  • the method of the invention comprises further, the steps of taking the casting out of the insulating material after step (v) is concluded and cooling it to room temperature, for instance on the air.
  • the method of the invention yields ausferritic ductile iron alloys.
  • the alloys are obtained as components or castings which have may different applications such as for instance, as automotive or railroad components or components for the construction, mining and agricultural industries.
  • the method presents the advantage that the manufacturing of ausferritic ductile iron alloys does not require the application of either subsequent conventional heat treatments after casting, nor controlled cooling and austempering in either a salt bath furnace nor in an electric furnace.
  • the invention refers to ausferritic ductile iron alloys produced by the method of the invention.
  • Example 1 method of the invention of preparing ausferritic ductile iron alloy
  • the extraction of the melt from the furnace to the ladle was made at a temperature of 1525°C.
  • the castings were keel Blocks Y2 following the standard norm UNE-EN 1563:1998.
  • thermocouple type k was inserted in the centre of the samples or keel Blocks Y2 in order to obtain the cooling curves ( figure 1 ).
  • the moulds were made of chemical bonded sand. Once the solidification was carried out, the castings were early shaken out of the mould at the temperature of 800oC. In total six keel blocks Y2 were poured.
  • the keel blocks Y2 were introduced into a metallic container (110 mm x 80 mm x 80 mm) comprising perlite in an amount enough to completely cover the keel blocks therein introduced.
  • Perlite has thermal conductivity between 0.04-0.06 W/mK.
  • Perlite had the following characteristics: mesh size of below 5 mm and density between 40-120 kg/m 3 .
  • the keel blocks Y2 were easily introduced in the container, and were easily completely covered with expanded perlite only due to their own weight.
  • Each keel block Y2 remained in the container for 30, 60 and 90 minutes respectively.
  • the other three keel blocks Y2 were air cooled until their temperature reached 300oC and were then each introduced into the same insulating material, also for 30, 60 and 90 minutes respectively. As it can be seen in Fig. 1 , the cooling curve corresponding to the keel Block 300oC and 30oC could not be completely registered since the corresponding thermocouple broke when the keel block was shaken out. Afterwards, the keel blocks Y2 were taken out of the insulating material and simply air cooled until room temperature.
  • the microstructure of the samples is shown in Figure 1 . These micrographies have been taken using an optical microscope (LEICA MEF 4) at 500 and 1000 magnifications. It can be seen, that completely ausferritic microstructures were achieved.
  • Completely ausferritic in the context of the present invention means 85% or more by volume of ausferrite, preferably 90% or more, more preferably 95% or more, and even more preferably 99% or more, the rest being pearlite and/or martensite.
  • the micrographs show that the shape of the ferrite needles changes depending on the temperature at which the samples are introduced and then held in the insulating material. It has been observed that the mechanical properties vary as follows: for higher remaining temperatures (400oC), the tensile strength decreases while the elongation and the impact resistance at room temperature for an unnotched specimen increase.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Silicates, Zeolites, And Molecular Sieves (AREA)
EP12382541.6A 2012-12-27 2012-12-27 Procédé de production de coulée de fonte ductile ausferritique Withdrawn EP2749658A1 (fr)

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EP12382541.6A EP2749658A1 (fr) 2012-12-27 2012-12-27 Procédé de production de coulée de fonte ductile ausferritique

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3026128A1 (fr) 2014-11-27 2016-06-01 Casa Maristas Azterlan Procédé de commande de microstructure brute ausferritique de pièces en fer ductile
EP3088537A1 (fr) * 2015-04-27 2016-11-02 Georg Fischer GmbH Procédé de production d'une fonte hpi
US9945003B2 (en) 2015-09-10 2018-04-17 Strato, Inc. Impact resistant ductile iron castings
PL423973A1 (pl) * 2017-12-20 2019-07-01 Spółka Akcyjna Odlewnie Polskie Żeliwo niestopowe ausferrytyczne, sposób wytwarzania odlewów z żeliwa niestopowego ausferrytycznego oraz zastosowanie takiego żeliwa i sposobu wytwarzania odlewów
PL423974A1 (pl) * 2017-12-20 2019-07-01 Spółka Akcyjna Odlewnie Polskie Żeliwo ausferrytyczne o podwyższonej wytrzymałości na ścieranie, sposób wytwarzania odlewów z żeliwa ausferrytycznego o podwyższonej wytrzymałości na ścieranie oraz zastosowanie takiego żeliwa
CN110184426A (zh) * 2019-07-04 2019-08-30 太仓欧克仓储设备有限公司 一种周转箱的热处理工艺
CN110295265A (zh) * 2019-06-25 2019-10-01 天津昌昊实业有限公司 一种奥贝球铁及其制备方法和应用

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4504527A (en) * 1981-02-23 1985-03-12 The Japan Steel Works, Ltd. Method for the insulation of heated metalic materials
US5139579A (en) * 1990-04-27 1992-08-18 Applied Process Method for preparing high silicon, low carbon austempered cast iron
US5753055A (en) * 1996-11-05 1998-05-19 Standard Car Truck Company Process for austempering ductile iron
US5878897A (en) * 1996-09-04 1999-03-09 Mcconway & Torley Corporation Slack reduced lock member for a type E raiway coupler
US20040071584A1 (en) * 2002-07-26 2004-04-15 Erre-Vis S.P.A. Spheroidal cast iron particularly for piston rings and method for obtaining a spheroidal cast iron

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4504527A (en) * 1981-02-23 1985-03-12 The Japan Steel Works, Ltd. Method for the insulation of heated metalic materials
US5139579A (en) * 1990-04-27 1992-08-18 Applied Process Method for preparing high silicon, low carbon austempered cast iron
US5878897A (en) * 1996-09-04 1999-03-09 Mcconway & Torley Corporation Slack reduced lock member for a type E raiway coupler
US5753055A (en) * 1996-11-05 1998-05-19 Standard Car Truck Company Process for austempering ductile iron
US20040071584A1 (en) * 2002-07-26 2004-04-15 Erre-Vis S.P.A. Spheroidal cast iron particularly for piston rings and method for obtaining a spheroidal cast iron

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
"Austempered ductile-iron castings - advantages, production, properties and specifications", MATERIALS AND DESIGN, LONDON, GB, vol. 13, no. 5, 1 January 1992 (1992-01-01), pages 285 - 297, XP024153210, ISSN: 0261-3069, [retrieved on 19920101], DOI: 10.1016/0261-3069(92)90191-J *
ALI REZA KIANI-RASHID ET AL., INTERNATIONAL FOUNDRY RESEARCH, vol. 63, no. 1, 2011
JANOWAK J F ET AL: "APPROACHING AUSTEMPERED DUCTILE IRON PROPERTIES BY CONTROLLED COOLING IN THE FOUNDRY", INTERNATIONAL CONFERENCE ON AUSTEMPERED DUCTILE IRON, XX, XX, 2 April 1984 (1984-04-02), pages 63 - 69, XP001182603 *
NT.J.CAST METALS RES., vol. 11, 1999, pages 483 - 488

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3026128A1 (fr) 2014-11-27 2016-06-01 Casa Maristas Azterlan Procédé de commande de microstructure brute ausferritique de pièces en fer ductile
EP3088537A1 (fr) * 2015-04-27 2016-11-02 Georg Fischer GmbH Procédé de production d'une fonte hpi
US9945003B2 (en) 2015-09-10 2018-04-17 Strato, Inc. Impact resistant ductile iron castings
PL423973A1 (pl) * 2017-12-20 2019-07-01 Spółka Akcyjna Odlewnie Polskie Żeliwo niestopowe ausferrytyczne, sposób wytwarzania odlewów z żeliwa niestopowego ausferrytycznego oraz zastosowanie takiego żeliwa i sposobu wytwarzania odlewów
PL423974A1 (pl) * 2017-12-20 2019-07-01 Spółka Akcyjna Odlewnie Polskie Żeliwo ausferrytyczne o podwyższonej wytrzymałości na ścieranie, sposób wytwarzania odlewów z żeliwa ausferrytycznego o podwyższonej wytrzymałości na ścieranie oraz zastosowanie takiego żeliwa
CN110295265A (zh) * 2019-06-25 2019-10-01 天津昌昊实业有限公司 一种奥贝球铁及其制备方法和应用
CN110295265B (zh) * 2019-06-25 2020-10-09 天津昌昊实业有限公司 一种奥贝球铁及其制备方法和应用
CN110184426A (zh) * 2019-07-04 2019-08-30 太仓欧克仓储设备有限公司 一种周转箱的热处理工艺

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