EP2322671A1 - Methode zur Vorhersage des Anteils an Vermikulargraphit in einem Gussstück - Google Patents

Methode zur Vorhersage des Anteils an Vermikulargraphit in einem Gussstück Download PDF

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Publication number
EP2322671A1
EP2322671A1 EP09380173A EP09380173A EP2322671A1 EP 2322671 A1 EP2322671 A1 EP 2322671A1 EP 09380173 A EP09380173 A EP 09380173A EP 09380173 A EP09380173 A EP 09380173A EP 2322671 A1 EP2322671 A1 EP 2322671A1
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EP
European Patent Office
Prior art keywords
area
vermicularity
degree
cast iron
pieces
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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
EP09380173A
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English (en)
French (fr)
Inventor
Pedro Inchausti Aguirre
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.)
Casa Maristas Azterlan
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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
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Priority to EP09380173A priority Critical patent/EP2322671A1/de
Priority to PCT/IB2010/002766 priority patent/WO2011051792A1/en
Publication of EP2322671A1 publication Critical patent/EP2322671A1/de
Ceased legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/10—Making spheroidal graphite cast-iron
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D2/00—Arrangement of indicating or measuring devices, e.g. for temperature or viscosity of the fused mass
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/42—Constructional features of converters
    • C21C5/46—Details or accessories
    • C21C5/4673—Measuring and sampling devices

Definitions

  • the characteristics of a cast iron do not depend only on its chemical composition, but also on its production process, both being factors which determine the shape in which the carbon present (combined, lamellar, spheroidal, compact, etc.) precipitates out during the solidification process.
  • the shape of the graphite defines the mechanical behavior of cast iron. In graphite cast irons, most of what is produced is spheroidal graphite cast iron and lamellar graphite cast iron, in which the graphites precipitate out in spheroidal and lamellar shapes, respectively.
  • the suitable material for manufacture is chosen depending on the features that the pieces must comply with and taking into account economic factors. Nevertheless, the properties of the material also depend on the perlite/ferrite ratio of the matrix structure.
  • VMI vermicular graphite cast iron
  • vermicular graphite cast iron compared to cast iron lamellar, the vermicular graphite cast iron has greater ductility and tensile strength, whereas compared to spheroidal cast iron, vermicular graphite cast iron has greater thermal conductivity, a better response to vibration and thermal shocks, as well as a lower shrinkage tendency during cooling.
  • type III compact
  • IV - V intermediate
  • VI spheroidal graphites
  • CGMet(%) The percentage of vermicular graphite or degree of vermicularity in the metal produced, hereinafter referred to as CGMet(%), is established by the proportion of each of these groups of graphite. The determination of this percentage is what offers a clear idea about the mechanical properties of the material.
  • each of the factors influencing the degree of vermicularity is the cooling rate of the metal during its solidification process, hereinafter referred to as CGMod(%) when the factors influencing the cooling rate, i.e., the thermal modulus, are taken into account in the calculation of the percentage of vermicular graphite.
  • WO9206809 describes a method for knowing the amount of modifying agent that must be added to the liquid metal to obtain the desired structure.
  • Patent uses two cooling curves recorded by means of thermocouples located in the thermal center and in the outer area in a metal sample obtained of the cast iron to be treated.
  • Patent EP0327237 describes a method in which a sample of cast iron treated with Mg is poured into a vessel containing a certain amount of Te and S or Se. If the active Mg in the cast iron is less than the amount that can be neutralized by the additions of S and Se, the presence of Te will force carbidic solidification. If there is a larger amount of active Mg than that with which the additions S and Se are neutralized, the solidification of the metal will be graphitic despite the presence of the Te.
  • EP0327237 furthermore indicates that by means of thermal testing in cups with different amounts of additions of S and Se, the Mg content necessary for the production of vermicular graphite cast iron can be controlled.
  • Patent WO9825133 describes a method for predicting the microstructure in which a graphite cast iron will solidify, by means of cooling curves, without referring to the different CGMod(%) that may occur in one and the same piece as a consequence of the different cooling rates occurring therein.
  • Patent Ru2337973C2 explains a system for obtaining spheroidal and vermicular cast iron, for single pieces or large-scale production by means of controlling the process depending on the amount of liquid metal to be used, the concentration of sulphur and oxygen and the time of the process.
  • Patent WO2007017350 relates to a process for obtaining cast iron with vermicular graphite with high operational security.
  • a magnesium treatment alloy composed of magnesium and another metal (to the exclusion of silicon) is added according to the invention to an iron melt with a sulphur content of less than 0.05% by weight kept in a treatment vessel in an inert atmosphere, until the magnesium content of the iron melt amounts to 0.005-0.018 % by weight.
  • Patent US6544359 describes a system for obtaining objects of vermicular cast iron from a cast iron melt with a carbon content at the desired final level and a silicon content below the desired final value, by means of adding magnesium compounds, for the purpose of regulating the amount of oxygen in the material.
  • the invention furthermore includes the opportunity to enter the necessary calculations in a metallurgical quality management program, the result thus being obtained in a simple and automated manner.
  • the present document describes a system for the control, in real time, of the percentage of vermicular graphite with which specific areas of pieces made of vermicular graphite cast iron will solidify.
  • the system herein described takes into consideration the effect of at least two factors: the metallurgical quality and the cooling rate with which pieces solidify.
  • the control of the metallurgical quality is carried out by means of thermal analysis and the subsequent treatment of the cooling curves recorded on an inoculated sample, a sample without inoculation and a sample with the addition of tellurium.
  • the cooling rate is included in the calculations by means of the parameter: inverse modulo. Its calculation is possible by means of applying reverse engineering. This parameter includes in its calculation all those factors influencing the rate at which the pieces cool.
  • a modifying agent Any agent which is added to the metal when it is in its liquid state and its purpose is to force the precipitation of the carbon in any of the previously mentioned shapes according to the ISO 945 standard is called a modifying agent.
  • Ce, Mg and Ti have traditionally been used as modifying agents. The first two are added for the purpose of forcing the precipitation of the graphite in any of types III to IV, whereas the third agent is added to control the modifying effect of the aforementioned agents.
  • a neutralizing agent is that agent which is combined with the modifying agents added, preventing their modifying action.
  • the value given indicates the proportion of graphites in one mm 2 of sample and of types III, IV and V according to ISO 945 standard, compared to the total number of graphite particles formed for the inoculated sample for thermal analysis.
  • the proposed method uses the thermal modulus (Mt) concept for predicting the CGMod(%) in specific portions of a piece.
  • This parameter, associated with the cooling rate, is obtained by means of classic methodology as the ratio between the volume of metal and the surfaces thereof that are able to remove heat.
  • CGMod % ′ f Mt , CGMet %
  • Mt the thermal modulus (cm) of the studied area
  • CGMet(%) the prediction of the percentage of vermicular graphite in the metal.
  • the actual cooling conditions of a piece do not correspond with those described for an isolated system, so it is necessary to define a new concept, such as that the inverse modulo (Mi).
  • This concept is associated with the cooling rate of the piece, external influence factors, such as coolants, molding variables, location of the piece in the mold, proximity of other pieces, etc., being included therein.
  • the metallographic analysis carried out in step 3 above is based on an image analysis program which, for each area of a piece intended to be studied, obtains five micrographs magnified 100 times.
  • the existing graphite particles are sub-divided into groups according to the shape factor to which they belong.
  • the final value obtained for the percentage of vermicular graphite by means of metallographic inspection is given as the average value obtained from the 5 measurements taken.
  • This value of the inverse modulo (Mi) is calculated for various qualities, i.e. for different vermicular graphite density values, so the value which is finally obtained is a mean value of those obtained in all the tests. It can generally be stated that there is little difference among the values obtained.
  • the huge advancement of the described system is based on the possibility of obtaining actual information about the degree of vermicularity in specific portions of the pieces.
  • the control of those areas intended for greater wear, mechanical requirements, etc. can thus be assured, more useful and accurate information than that which is offered by the other available methods thus being obtained.
  • lamellar graphites which is very important since their appearance, even though minor or in isolated cells, causes a drastic reduction of the mechanical properties of fracture load or elongation in the material, is very reliably predicted by means of the proposed system.
  • lamellar graphites The importance of preventing the formation of lamellar graphites can be found in the fact that the designers of pieces determine the minimum thicknesses thereof based on the mechanical properties inherent to the material in which they will be manufactured. When pieces are made of vermicular graphite cast iron, the formation of lamellar graphites causes a reduction in the tensile strength of the material, whereby risking a fracture of the piece while it is functioning.
  • the method has demonstrated its effectiveness for the control of the processes in which the spheroidization treatments have been carried out by means of additions of Ce or Mg (with or without the addition of Ti).
  • Figure 3 shows an image of the brake disc in which the areas to be controlled are indicated.
  • Figure 4 shows an image of the turbo manifold in which the areas to be controlled are indicated.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)
EP09380173A 2009-10-30 2009-10-30 Methode zur Vorhersage des Anteils an Vermikulargraphit in einem Gussstück Ceased EP2322671A1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP09380173A EP2322671A1 (de) 2009-10-30 2009-10-30 Methode zur Vorhersage des Anteils an Vermikulargraphit in einem Gussstück
PCT/IB2010/002766 WO2011051792A1 (en) 2009-10-30 2010-10-29 System for predicting the percentage of graphitization in specific areas of pieces of vermicular graphite cast iron

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP09380173A EP2322671A1 (de) 2009-10-30 2009-10-30 Methode zur Vorhersage des Anteils an Vermikulargraphit in einem Gussstück

Publications (1)

Publication Number Publication Date
EP2322671A1 true EP2322671A1 (de) 2011-05-18

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EP09380173A Ceased EP2322671A1 (de) 2009-10-30 2009-10-30 Methode zur Vorhersage des Anteils an Vermikulargraphit in einem Gussstück

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WO (1) WO2011051792A1 (de)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB201307334D0 (en) 2013-04-23 2013-05-29 Novaucd Process

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4667725A (en) * 1984-09-12 1987-05-26 Sinter-Cast Ab Method for producing cast-iron, and in particular cast-iron which contains vermicular graphite
EP0327237A2 (de) 1988-02-05 1989-08-09 Bcira Verfahren zur Feststellung des Magnesiumgehaltes eines mit Magnesium behandelten Gusseisens
WO1992006809A1 (en) 1990-10-15 1992-04-30 Sintercast Ltd. A method for the production of compacted graphite cast iron
WO1998025133A1 (en) 1996-12-04 1998-06-11 Sintercast Ab Method for judging the properties of molten cast iron
US6354356B1 (en) * 1998-06-25 2002-03-12 Nissabu Corporation Method for the determination of the form of graphite in spheroidal and compacted/vermicular graphite cast irons
US6544359B1 (en) 1998-03-27 2003-04-08 Cgi-Promotion Ab Method to produce compacted graphite iron (CGI)
WO2007017350A1 (de) 2005-08-05 2007-02-15 Fritz Winter Eisengiesserei Gmbh & Co. Kg Verfahren zum herstellen von vermikulargraphitguss

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4667725A (en) * 1984-09-12 1987-05-26 Sinter-Cast Ab Method for producing cast-iron, and in particular cast-iron which contains vermicular graphite
EP0327237A2 (de) 1988-02-05 1989-08-09 Bcira Verfahren zur Feststellung des Magnesiumgehaltes eines mit Magnesium behandelten Gusseisens
WO1992006809A1 (en) 1990-10-15 1992-04-30 Sintercast Ltd. A method for the production of compacted graphite cast iron
WO1998025133A1 (en) 1996-12-04 1998-06-11 Sintercast Ab Method for judging the properties of molten cast iron
US6544359B1 (en) 1998-03-27 2003-04-08 Cgi-Promotion Ab Method to produce compacted graphite iron (CGI)
US6354356B1 (en) * 1998-06-25 2002-03-12 Nissabu Corporation Method for the determination of the form of graphite in spheroidal and compacted/vermicular graphite cast irons
WO2007017350A1 (de) 2005-08-05 2007-02-15 Fritz Winter Eisengiesserei Gmbh & Co. Kg Verfahren zum herstellen von vermikulargraphitguss

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