US20100284849A1 - Austenitic cast iron and manufacturing process for the same, austenitic-cast-iron cast product and component part for exhaust system - Google Patents

Austenitic cast iron and manufacturing process for the same, austenitic-cast-iron cast product and component part for exhaust system Download PDF

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US20100284849A1
US20100284849A1 US12/675,283 US67528308A US2010284849A1 US 20100284849 A1 US20100284849 A1 US 20100284849A1 US 67528308 A US67528308 A US 67528308A US 2010284849 A1 US2010284849 A1 US 2010284849A1
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cast iron
austenitic cast
austenitic
set forth
cast
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Tomohei Sugiyama
Manabu Ishikawa
Hiroyuki Isomura
Mamoru Kojima
Naoki Yamamoto
Kyoichi Kinoshita
Takao Fujikawa
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Toyota Industries Corp
Mie Prefecture
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Toyota Industries Corp
Mie Prefecture
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Assigned to MIE PREFECTURE, KABUSHIKI KAISHA TOYOTA JIDOSHOKKI reassignment MIE PREFECTURE ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: FUJIKAWA, TAKAO, ISHIKAWA, MANABU, ISOMURA, HIROYUKI, KINOSHITA, KYOICHI, KOJIMA, MAMORU, SUGIYAMA, TOMOHEI, YAMAMOTO, NAOKI
Publication of US20100284849A1 publication Critical patent/US20100284849A1/en
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C37/00—Cast-iron alloys
    • C22C37/06—Cast-iron alloys containing chromium
    • C22C37/08—Cast-iron alloys containing chromium with nickel
    • 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
    • C21C1/105—Nodularising additive agents
    • 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 relates to an austenitic cast iron, which is excellent in terms of heat resistance, and the like; to a cast product, which is comprised of that; to a production process for the same; and to a component part for exhaust system.
  • C in the alloy whose major component is made of iron-carbon exceeds the maximum solid solubility limit in ⁇ iron (e.g., about 2% by mass), and the cast iron is accompanied by eutectoid solidification.
  • various alloying elements are added.
  • Such a cast alloy is referred to as an alloy cast iron, and especially those cast irons with great alloying-element contents are referred to as high-alloy cast irons.
  • These high-alloy cast irons are usually divided into ferritic cast ions and austenitic cast irons roughly depending on the difference between the crystalline structures of their crystallizing bases.
  • the austenitic cast irons are comprised of austenite phase (or ⁇ phase) mainly, not to mention in high-temperature region, but in ordinary-temperature range as well, they are good in terms of heat resistance, oxidation resistance, corrosion resistance, and the like; and are moreover good in terms of ductility, toughness, and so forth.
  • the austenitic cast irons are often used for members that are made use of in harsh environments such as high-temperature atmospheres.
  • harsh environments such as high-temperature atmospheres.
  • turbocharger housings, exhaust manifolds, catalyst cases, and the like are given.
  • Any one of the members is a component part, and the like, which is exposed to high-temperature exhaust gases, and consequently which is required to exhibit long-term durability.
  • various types are available in the austenitic cast irons as well, and the following are representative ones: Niresist, nimol, nicrosilal, monel, minober, nomag, and the like.
  • JIS Japanese Industrial Standards
  • 9 types are prescribed for the flake graphitic cast iron (e.g., FCA)
  • 14 types are prescribed for the spheroidal graphitic cast iron (e.g., FCDA).
  • an austenite phase has been made obtainable even in ordinary-temperature range by having them contain Ni, namely, an austenite stabilizing element, in a large amount (Ni: from 18 to 36%, for instance).
  • Ni namely, an austenite stabilizing element
  • This Ni is expensive considerably compared with Fe, namely, the parent material, and the other alloying elements, and consequently cast products comprising the conventional austenitic cast irons have been high costs considerably.
  • Niresist As per JIS
  • an austenitic cast iron whose Ni content is less comparatively has also come to be known publicly.
  • Niresist FCDA-NiMn137 as per JIS
  • FCDA-NiMn137 as per JIS is poor in term of oxidation resistance.
  • X-ray analysis or XRD
  • the resulting austenitic cast irons have such a drawback as well that the workability worsens, because work-induced martensite that is very hard appears at the time of cutting work.
  • Patent Literature No. 1 Japanese Unexamined Patent Publication (KOKAI) Gazette No. 58-27,951
  • Patent Literature No. 1 discloses that, in relation to oxidation resistance, namely, an index of heat resistance concerning austenitic cast iron, the more the Si content enlarges the less the oxidized weight increment per unit area becomes (see FIG. 6 of Patent Literature No. 1).
  • the Si content that becomes excessive results in declining the elongation of austenitic cast iron, and in worsening the machinability. Consequently, considering the reliability and the mass-producibility of heat-resistant members comprising austenitic cast irons, and the like, it is not practical to enhance the oxidation resistance to such a level that is sufficient in view of practical use by only adjusting the Si content.
  • the present invention is one which has been done in view of such circumstances. Specifically, it is an object to provide a low-cost austenitic cast iron that is an austenitic cast iron whose contained amount of Ni is less, and which is excellent not only in terms of thermal-fatigue strength, and the like, but also in terms of oxidation resistance. Moreover, in addition to that, it is another object to provide austenitic cast products comprising that austenitic cast iron, and a manufacturing process for the same, and furthermore exhaust-system component parts, namely, some of those austenitic cast products.
  • the present inventors studied earnestly to solve this assignment; as a result of their repeated trial and error, they succeeded in obtaining an austenitic cast iron that exhibited favorable characteristics, even in the case of reducing the contained amount of nickel (Ni), by adjusting the contained amounts of carbon (C), silicon (Si), chromium (Cr), nickel (Ni), manganese (Mn) and copper (Cu).
  • Ni nickel
  • Cr chromium
  • Ni nickel
  • Mn manganese
  • Cu copper
  • the present inventors arrived at completing a variety of inventions, which will be described later, by developing these achievements.
  • an austenitic cast iron according to the present invention is characterized in that:
  • the balance comprising iron (Fe), inevitable impurities and/or a trace-amount modifier element, which is effective in improving characteristic, in a trace amount;
  • austenitic cast iron being a cast iron that is structured by a base comprising an Fe alloy in which an austenite phase makes a major phase in ordinary-temperature region;
  • Mn from 0.1 to 8%
  • the Ni content becomes a considerably small amount relative to the entire cast iron in the austenitic cast iron according to the present invention.
  • base in which an austenite phase which is stabilized in ordinary-temperature range, makes a major phase.
  • an austenite phase was obtained successfully by setting, even though on the premise of that small-amount Ni content, the respective contained amounts of the other alloying elements, namely, C (especially, C s , a solute carbon content), Si, Cr, Mn and Cu to appropriate ranges that satisfy the aforementioned respective conditions.
  • the oxidation resistance which is indexed by a later-described oxidized weight decrement, and the like, is improved by means of containing Cr or Cu in an adequate amount even while suppressing the upper limit of the Si content.
  • Cr forms a passive film, which comprises dense and fine chromium oxides, adjacent to the surface of the austenitic cast iron and has then improved its oxidation resistance.
  • Cr combines with carbon in the cast-iron base to precipitate carbides therein, and accordingly is capable of improving the high-temperature proof stress of the cast iron by means of precipitation strengthening of the base.
  • Cr that becomes excessive is not preferable, because carbides increase so that the toughness and workability, which are indexed by means of the Charpy-impact value and so forth decline.
  • the Cr content can be from 0.5 to 4%.
  • Cu yields an effect of making the fcc structure more stable, because it has an fcc structure, namely, a crystalline structure that is similar to austenite at ordinary temperature, and because it has a dense structure that is much less likely to pass oxygen than is ferrite with a bcc structure.
  • Cu does not at all enter oxidized film, and then Cu is enriched at the interface between the oxidized film and metal; accordingly Cu turns into an fcc structure possessing the lattice constant that differs from that of parent phase; consequently Cu demonstrates a barrier-layer effect that inhibits the interstitial action of oxygen atoms possessing such an energy state that they are likely to force into the parent base; and it is believed therefore to have its oxidation resistance improve.
  • Cu is an effective element for refining crystalline particles in the base's structure and then having the high-temperature proof stress improve. Further, as a result of being studied earnestly by the present inventors, it was understood that Cu also yields an effect of decreasing hardness, and consequently it is possible to intend to improve the workability of austenitic cast product.
  • the present invention since to have oxidation resistance improve is one of the objectives, it is preferable to involve Cu and Cr, which improve oxidation resistance, in an amount of 0.5% or more by sum total. It is preferable that the lower limit of this Cu+Cu can be 1%, 1.5%, or further 2%.
  • Ni content 8 to 14% in obtaining an austenitic cast iron, which is provided with strength, heat resistance (including oxidation resistance), elongation, ductility, toughness, workability, and the like, in a well balanced manner like the present invention, at low cost.
  • the present invention can even be a manufacturing process for austenitic cast iron that is characterized in that it comprises:
  • the manufacturing process for austenitic cast iron according to the present invention can even be one being characterized in that it comprises:
  • an auxiliary-agent addition step of adding an auxiliary agent which includes at least one member being selected from the group consisting of inoculant agents that make cores of graphite to be crystallized or precipitated, and spheroidizing agents that facilitates spheroidizing of the graphite, to the modifier-free molten metal directly or indirectly;
  • a pouring step of pouring a molten metal into a casting die the molten metal being after the auxiliary-agent addition step or during the auxiliary-agent addition step;
  • a cast product comprising the aforesaid austenitic cast iron is obtainable, the austenitic cast iron in which substantially spheroidal graphite is crystallized or precipitated within the resulting base.
  • the austenitic cast iron (including the austenitic cast product) according to the present invention, or the manufacturing process for the same according to the present invention, can have contents as set forth below. Moreover, it is even allowable to further add one or two or more constitutions, which are selected arbitrarily from the constitutions that are listed below, to the aforementioned present invention.
  • the balance comprising Fe, inevitable impurities and/or a trace-amount modifier element, which is effective in improving characteristic, in a trace amount;
  • austenitic cast iron being a cast iron that is structured by a base comprising an Fe alloy in which an austenite phase makes a major phase in ordinary-temperature region;
  • a carbon equivalent (hereinafter being simply expressed as “C eq ”) according to one of the following expressions being given by the respective contained amounts of C and Si satisfies a first condition according to the following expressions; and simultaneously the contained amounts of Ni satisfies a second condition according to the following expressions; and the contained amount of Cu satisfies a third condition according to the following expressions; when the entirety of said cast iron is taken as 100% by mass (hereinafter being simply expressed to as “%”); and
  • Ni eq nickel equivalent
  • Cr eq chromium equivalent
  • the Ni content is set to a considerably small amount relative to the entire cast iron, as specified in the second condition. Consequently, in view of the conventional technical common sense, it seems that no base with austenite phase, which is stabilized in ordinary-temperature range, is obtainable.
  • an austenite phase was obtained successfully by setting, even though on the premise of that small-amount Ni content, the respective contained amounts of the other alloying elements, namely, C (especially, C s ), Si, Cr, Mn and Cu, to proper ranges that satisfy the aforementioned respective conditions.
  • the respective conditions that prescribe the present invention will be explained.
  • the carbon equivalent (C eq ) is prescribed like the first condition, because the present invention is anyway a cast iron, which is accompanied by peritectic solidification.
  • the Ni content is prescribed like the second condition, because the present invention is a cast iron whose Ni is reduced. Even when considering the second condition, relative to the composition of the entire cast iron, on the premise of the first condition, the austenitic cast iron according to the present invention is distinguishable from many other conventional austenitic cast irons.
  • the Cu content is prescribed like the third condition in order to obtain an austenitic cast iron that is excellent in terms of elongation performance at the time of high temperatures.
  • peritectic Cu exists in austenitic cast irons that include Cu abundantly in the analyzed compositions. It is speculated that the resultant peritectic Cu worsens the elongation performance of the austenitic cast irons at the time of high temperatures.
  • bases comprising Fe alloys, on the basis of those Ni content and C eq . That is, such indexes as the nickel equivalent (Ni eq ) and chromium equivalent (Cr eq ) that are found from the basic elements were introduced, and then a composition of the entire base, which makes the core of the cast-iron structure, is determined by means of the fourth and fifth conditions.
  • austenitic cast irons which satisfy the aforementioned fourth and fifth conditions, do not have any lamellar structure that exists in austenite even when setting Cu to fall in the aforementioned range. And, it is speculated that they are materials that are strong against thermal fatigue, because no lamellar structure exists in austenite.
  • the austenitic cast iron whose basic elements satisfy the aforementioned first through fifth conditions is an epoch-making cast iron that is not on the extension of the conventional technical common sense.
  • the austenitic cast iron according to the present invention exhibits austenite cast iron's other excellent properties because of its structure and composition.
  • the austenitic cast iron according to the present invention it is possible to identify its composition, on the premise of the Ni content being specified in said second condition, by setting the respective alloying elements, which constitute the basic elements, individually, or combining themvariously, with a plurality of methods, that is, other than the methods being prescribed as described above or along with the methods being prescribed as described above.
  • the austenitic cast iron according to the present invention is prescribed by a composition of the entire cast iron.
  • the present invention can be an austenitic cast iron that comprises: basic elements comprising C, Si, Cr, Ni, Mn and Cu; and the balance comprising Fe, inevitable impurities and/or a trace-amount modifier element, which is effective in improving characteristic, in a trace amount; and which is a cast iron that is structured by a base comprising an Fe alloy in which an austenite phase makes a major phase in ordinary-temperature region; and the present austenitic cast iron can be prescribed as an austenitic cast iron as well that is characterized in that:
  • said basic elements are set so that not only a carbon equivalent (hereinafter being simply expressed as “C eq ”) according to the following expression that is given by means of the respective contained amounts of C and Si, but also Ni, Cu and Si fall within compositional ranges that are specified as mentioned below when the entirety of said cast iron is taken as 100% by mass (hereinafter being simply expressed as “%”):
  • the austenitic cast iron according to the present invention is prescribed by a composition of the entire cast iron is specified as follows.
  • the present invention can be an austenitic cast iron that comprises: basic elements comprising C, Si, Cr, Ni, Mn and Cu; and the balance comprising Fe, inevitable impurities and/or a trace-amount modifier element, which is effective in improving characteristic, in a trace amount; and which is a cast iron that is structured by a base comprising an Fe alloy in which an austenite phase makes a major phase in ordinary-temperature region; and the present austenitic cast iron can be prescribed as an austenitic cast iron as well that is characterized in that:
  • said basic elements are set so that not only a carbon equivalent (hereinafter being simply expressed as “C eq ”) according to the following expression that is given by means of the respective contained amounts of C and Si, but also Ni, Cu and Cr fall within compositional ranges that are specified as mentioned below when the entirety of said cast iron is taken as 100% by mass (hereinafter being simply expressed as “%”):
  • the “austenite phase” being referred to in the present invention be an austenite single phase completely. That is, the clause, “austenite phase makes a major phase,” purports to make the following permissible: of course not only such a case as being comprised of an austenite single phase alone that exhibits 100% austenite by X-ray analysis, and which does not include any lamellar structure that is made of those like martensite and perlite in the austenite; in addition thereto but also such a case as including a martensite phase slightly.
  • an austenite single phase can be present more than 50% by volume, 60% by volume or more, 70% by volume or more, 80% by volume or more, 90% by volume or more, or further 95% by volume or more.
  • the base's structure is an austenite phase or not is prescribed by means of the above-described fourth condition substantially. That is, it is possible to narrow down a metallic structure to be obtained to an austenite single phase by setting the intercept of a border line, which demarcates the lower limit of Ni eq in the aforementioned fourth condition, at 21.6. Note that it should be notified that the indexing of B x , which designates the intercept of the border line that is indicated in the present invention, is an expediential one.
  • the upper limit of Ni eq relative to the entire base is not limited essentially as far as Ni is a small amount relative to the entire cast iron as specified in the second condition, because it is one of the objectives to obtain a cast iron that has a base being an austenite phase in ordinary-temperature region while reducing the content of Ni to be made use of.
  • the elements other than Ni also exhibit limitations in terms of their solute contents in Fe. Moreover, those elements that get greater is not preferable, not only because costs have risen though the reduction of the Ni content can be intended, but also because desirable cast-iron structures have become less likely to obtain.
  • the upper limit of Ni eq is set at 30%, it is preferable that the upper and lower limits of Ni eq can be either one of 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or further 20%.
  • the upper limit of Cr eq is set at 13.5% in the present invention while considering the generation circumstances of carbides that are believed to be the cause of fatigue-strength decline.
  • the upper and lower limits of Cr eq can be either one of 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, or 4%.
  • the “trace-amount modifier element” being referred to in the present invention is a trace-amount element that is effective in improving characteristic.
  • it can be an element that contributes to metallic structure, such as spheroidizing graphite that crystallizes or precipitates or increasing the number of the particles, and making austenite phase finer or stabilizing it.
  • it can also be an element that contributes to mechanical characteristic, such as strength in room-temperature region or high-temperature region, high-temperature durability (i.e., creep strength, and the like), toughness, and elongation.
  • it can even be an element that contributes to oxidation resistance, thermal expandability, thermal conductivity, workability, and so forth.
  • it can also be an element that contributes to castability, such as flowability at the time of casting, and suppressing cast defects like cracks, shrinkage or pores.
  • impurities being included in raw materials, impurities getting mingled or the like at the time of casting, and so on. They are elements that are difficult to remove because of being costly, or due to technical reasons, etc. For example, as for such inevitable impurities, phosphorous (P), and the like, are given.
  • the compositions of the trace-amount modifier element and inevitable impurities are not limited in particular, because the compositions of the basic elements are important.
  • the compositions of the basic elements are important.
  • the inevitable impurities even when being an austenitic cast iron in which no trace-amount modifier element is included, not to mention the inevitable impurities, it falls within the range of the present invention.
  • it even when being an element that can make a trace-amount modifier element, it is permissible to treat it also as an inevitable impurity depending on its contained amount, or an application of the resulting cast iron, and the like.
  • compositions that are used in the present invention, the following are given: a compositional range relative to the entirety of a cast iron; and another compositional range relative to the entirety of a base, namely, a part that constitutes that cast iron.
  • the compositional range relative to the entire base is a portion that is relevant to the Ni eq and Cr eq which affect the base's structure fundamentally. Therefore, compositions, which the present specification prescribes herein regarding portions other than the portion that is relevant to the Ni eq and Cr eq , mean componential compositions relative to the entirety of cast irons unless otherwise notified.
  • FIG. 1 is an XRD diagram on various cast irons with different compositions.
  • FIG. 2 is a correlation diagram for showing Cr eq —Ni eq regarding various cast irons with different compositions.
  • FIG. 3 is an XRD diagram on a cast iron (e.g., Test Specimen No. 2-2) that only had a distinct plate thickness to each other.
  • a cast iron e.g., Test Specimen No. 2-2
  • FIG. 4A is photomicrographs for showing metallic structures at respective positions in a surface and the inside of a cast-product sample (e.g., Test Sample No. 3-1).
  • FIG. 4B is photomicrographs for showing metallic structures at respective positions in a surface and the inside of a cast-product sample (e.g., Test Sample No. 3-2).
  • FIG. 5 is photomicrographs for showing metallic structures regarding respective cast irons, namely, a basic material (FCDA-NiMn137 as per JIS) and a Cu-added material made by adding Cu to that base material, together with the Schaeffler's structural diagram on which their positions are designated.
  • FIG. 6 is photomicrographs for showing metallic structures of cast-product samples (e.g., Test Sample Nos. 6-1 through 6-12).
  • FIG. 7 is a graph for illustrating a relationship between Cu addition amount and elongation in Fourth Test.
  • FIG. 8 is graph for illustrating a relationship between Cr addition amount and proof stress in Fourth Test.
  • FIG. 9 is an XRD diagram on cast irons with different compositions.
  • FIG. 10 is diagrams on correlations between the temperatures of various cast irons and the linear expansion coefficients, wherein the correlation diagram labeled (a) in the same drawing corresponds to Test Specimen No. 6-5; the correlation diagram labeled (b) in the same drawing corresponds to Test Specimen No. 4-3; the correlation diagram labeled (c) in the same drawing corresponds to Test Specimen No. R3; the correlation diagram labeled (d) in the same drawing corresponds to Test Specimen No. R4; and the correlation diagram labeled (e) in the same drawing corresponds to Test Specimen No. R6; respectively.
  • FIG. 11 is a bar graph for illustrating oxidized weight decrements of various test specimens.
  • FIG. 12 is diagrams for illustrating correlations between oxidized weight decrements and amounts of contained elements that are relevant to various test specimens, wherein labeled (a) in the same drawing is relevant to the contained amounts of Cr; and labeled (b) in the same drawing is relevant to the contained amounts of Ni.
  • FIG. 13 is diagrams for illustrating correlations between oxidized weight decrements and amounts of contained elements that are relevant to various test specimens, wherein labeled (a) in the same drawing is relevant to the contained amounts of Mn; and labeled (b) in the same drawing is relevant to the contained amounts of Cu.
  • FIG. 14 is a bar graph for illustrating Charpy-impact values of various test specimens.
  • FIG. 15 is a diagram for illustrating a correlation between Charpy-impact values and contained Cr amounts that are relevant to various test specimens.
  • FIG. 16 a bar graph and dispersion diagram for illustrating 0. 2% proof stresses and fracture elongations of various test specimens at 800° C.
  • FIG. 17 is diagrams for illustrating correlations between fracture elongations and amounts of contained elements that are relevant to various test specimens, wherein labeled (a) in the same drawing is relevant to the contained amounts of Cr; and labeled (b) in the same drawing is relevant to the contained amounts of Cu.
  • FIG. 18 is a bar graph for illustrating hardnesses of various test specimens.
  • FIG. 19 is a photograph for showing misrun defects which make an index for evaluating the various test specimens' molten-metal running properties.
  • FIG. 20 is a bar graph for relatively evaluating molten-metal running properties exhibited by various test specimens, and illustrates them with respect to that of Test Specimen No. 7-1 being taken as “1.”
  • FIG. 21 is a bar graph for illustrating thermal-fatigue lives of various test specimens.
  • FIG. 22 is a bar graph for illustrating thermal-fatigue lives of various test specimens.
  • FIG. 23 is a graph for illustrating correlations between values of hardness rise and plate thicknesses of a test specimen when various elements were added in an amount of 1%.
  • FIG. 24 is photographs for explaining a method of quantifying shrinkage magnitudes in various test specimens.
  • FIG. 25 is a bar graph for relatively evaluating shrinkage magnitudes exhibited by various test specimens, and illustrates them with respect to that of Test Specimen No. R3 being taken as “1.”
  • FIG. 26 is a graph for illustrating correlations between average linear expansion coefficients of various test specimens and widths of heating temperatures.
  • FIG. 27 is a bar graph for illustrating average linear expansion coefficients of various test specimens.
  • FIG. 28 is a bar graph for illustrating thermal conductivities of various test specimens.
  • FIG. 29 is a bar graph for illustrating oxidized weight decrements of various test specimens at respective heating temperatures.
  • FIG. 30 is a bar graph for illustrating proof stresses of various test specimens at respective temperatures.
  • FIG. 31 is a bar graph for illustrating tensile strengths of various test specimens at respective temperatures.
  • FIG. 32 is a bar graph for illustrating fracture elongations of various test specimens at respective temperatures.
  • FIG. 33 is a bar graph for illustrating thermal-fatigue lives of various test specimens under respective conditions.
  • An austenitic cast iron according to the present invention comprises basic elements, and Fe, namely, the balance.
  • the basic elements comprise six types of elements, namely, C, Si, Cr, Ni, Mn and Cu.
  • five elements, namely, C, Si, Cr, Ni and Mn make the basic elements.
  • the actions or functions of each of these respective elements, and their suitable compositions will be explained.
  • C drops the molten temperature of Fe, and enhances the flowability of molten metal (including modifier-free molten metal). Consequently, it is an indispensable element for ferrous casting. Since C in Fe—C system alloys exceeds the maximum solid-solubility limit so that cast irons are accompanied by eutectic solidification, the lower limit of C can be 1.7%, 1.8%, 1.9%, 2%, or 2.1% fundamentally; and its upper limit can be 5%, or further 4.3%. Note that C that exceeds the solid-solubility limit crystallizes as graphite.
  • the lower limit of C can be 2%, or 2.5%, and that its upper limit can be 5%, or 3.5%.
  • solute carbon content (C s ), which becomes necessary for calculating the Ni eq being referred to in the present invention can be found essentially by analyzing the composition of Fe base structure, or by subtracting a total amount of C, which crystallized or precipitated graphite and carbides, such as cementite (Fe 3 C), have consumed, from the entire amount of blended C.
  • Si lowers the eutectic temperature of metastable system, facilitates the eutectic crystallization of ⁇ Fe-graphite, and then contributes to the crystallization of graphite. Moreover, Si forms passive films, which comprise silicon oxide in the vicinity of crystallizing graphite's surface, and thereby enhances the oxidation resistance of cast iron.
  • the lower limit of Si can be 2%, 3%, or further 3.5%.
  • the upper limit of Si can be 6%, 5.5%, 5%, or further 4.5%.
  • the lower limit of C eq can be set at 2.1%, at 2.5%, or further at 3%.
  • its upper limit can be set at 5%, or at 4.3%, namely, the eutectic point in the Fe—C system phase diagram, or further at 3.5%.
  • Cr binds with carbon in cast-iron base to precipitate carbides therein, and then improves the high-temperature proof stress of cast iron by means of the precipitation strengthening of the resulting base. Moreover, it makes it possible to improve the oxidation resistance because it forms passive films, which comprise dense and fine chromium oxides in the vicinity of the resulting cast iron's surface.
  • the lower limit of Cr can be 0.1%, 0.3%, 0.5%, 0.7%, 1%, 1.2%, or further 1.5%.
  • the upper limit of Cr can be 6%, 5%, 4%, 3%, 2.5%, or further 2%.
  • Ni is an effective element in the austenitization of base's structure. When Ni is too little, it is hard to obtain stable austenite phase. On the other hand, when Ni becomes too much, making austenitic cast iron inexpensive by means of the reduction of Ni content, namely, one of the objectives of the present invention, cannot be intended.
  • the lower limit of Ni can be 12%, 11%, 10%, 9%, 8%, or further 7%.
  • the upper limit of Ni can be 15%, 14%, 13%, 12%, 11%, 10%, or further 9%.
  • Cu and Mn are effective elements in the austenitization of base's structure, as well as Ni.
  • the upper limit of Ni according to the present invention is no higher than 15%.
  • C s falls within a virtually constant range (e.g., from 0 to 0.8%).
  • the C s content falls in such a range, because the solute amount of C in ⁇ Fe declines from 2.1%, namely, the maximum, to 0.8% approximately as being accompanied by temperature decline in the Fe—C binary system phase diagram.
  • Cast-iron test specimens were made ready, cast-iron test specimens which comprised the following, respectively: a basic material (Fe-3% C-2.3% Si-13% Ni-7% Mn equivalent to FCDA-NiMn137 as per JIS, that is, equivalent to later-described Test Specimen No. R2 in Table 1A); and a Cu-added material in which Cu was added in an amount of 6.5% to this basic material (equivalent to later-described Test Specimen No. 1-1 in Table 1A).
  • a basic material Fe-3% C-2.3% Si-13% Ni-7% Mn equivalent to FCDA-NiMn137 as per JIS, that is, equivalent to later-described Test Specimen No. R2 in Table 1A
  • a Cu-added material in which Cu was added in an amount of 6.5% to this basic material (equivalent to later-described Test Specimen No. 1-1 in Table 1A).
  • FIG. 5 all together: structural photographs in which these were observed; and their positions,
  • the basic material has a quasi-austenite structure of “A”+“M.” This fact was also ascertained from the structural photograph of the basic material. That is, it was ascertained that the basic material's base comprised an austenite phase (or ⁇ phase), and lamellar carbides that were formed of 2 phases, namely, carbide layers, which were seemed to precipitate from that ⁇ phase during the process of cooling at the time of casting, and an ⁇ phase.
  • the compositions of the major elements were as follows: 2.3% Si; 10.4% Ni; 6.5% Mn, and 7.2% Cu.
  • the resulting position falls in the martensite region (or “M” region).
  • the base of the Cu-added material should come to be positioned essentially in the austenite single phase region (i.e., “A” region), so to speak, on the Schaeffler's structural diagram.
  • A austenite single phase region
  • Ni eq 22.5 or more enters the “A” region on the conventional Schaeffler's structural diagram.
  • the coefficient of Cu is set at “1” in calculating Ni eq .
  • the lower limit of Cu can be 0%, 0.1%, 0.3%, 0.5%, 0.7%, 1%, or further 1.2%. It is preferable that the upper limit of Cu can be 3%, 2.5%, 2%, 1.8%, or further 1.8%.
  • the lower limit of Cu being 0% means that 0% ⁇ Cu.
  • the lower limit of Cu being 0% means that 0% ⁇ Cu.
  • Mn is also an effective element in the removal and the like of S that becomes the cause of flowability worsening and embrittlement.
  • the lower limit of Mn can be 0%, 0.1%, 0.5%, 1%, 2%, 2.5%, 3%, 4%, or further 5%. It is preferable that the upper limit of Mn can be 9%, 8%, 7%, or further 6%.
  • a trace-amount element it is preferable to make a trace-amount element be contained in order to improve a variety of characteristics, such as the metallic structure of austenitic cast iron (or cast product), the oxidation resistance, the corrosion resistance, the strength in ordinary-temperature region or high-temperature region, mechanical characteristics like strength or toughness, and electric characteristics.
  • Austenitic cast irons that include such a modifier element also falls within the limitations of the present invention naturally as far as the basic elements fall within the above-described ranges.
  • the trace-amount modifier element can be the following, for instance:magnesium (Mg), rare-earth elements (R.E.), aluminum (Al), calcium (Ca), barium (Ba), bismuth (Bi), antimony (Sb), tin (Sn), titanium (Ti), zirconium (Zr), molybdenum (Mo), vanadium (V), tungsten (W), niobium (Nb), or nitrogen (N), and the like.
  • each of these elements can be adjusted appropriately depending on characteristics that are required for austenitic cast irons. However, from the viewpoints of influences and so forth to costs and the compositions of the basic elements, it is preferable that the trace-amount modifier elements can be 1% or less, 0.8%, or further 0.6% or less in a total contained amount.
  • An added trace-amount modifier element might possibly disappear and the like during casting, because the melting point is lower than that of Fe. Accordingly, the content of each of the respective elements does not necessarily coincide with the total addition amount of that element. Consequently, as far as being effective in the improvement and so forth of cast structure, it is permissible that the contained amount of that trace-amount modifier element can be at the minimum level that is detectable.
  • a representative trace-amount modifier element is each of the respective elements that are included in an inoculant agent, which facilitates the crystallization of graphite within Fe base, or a spheroidizing agent, which facilitates the spheroidizing of resultant crystallized graphite.
  • An auxiliary agent such as an inoculant agent or spheroidizing agent, is blended at the time of preparing a molten metal, or is added appropriately at the time of casting.
  • its contained elements and the contained amounts of the respective elements are not fixed, but vary greatly.
  • Mg and R.E. e.g., cerium (Ce) especially
  • Ce cerium
  • the addition amount can be adjusted to such an extent that its lower limit becomes 0.02%, or further 0.03%, relative to the entire cast iron being taken as 100%.
  • the upper limit of the contained Mg amount is not limited in particular as far as it does not affect the compositions of the basic elements, it can be, in actuality however, 0.07%, or further 0.06%, relative to the entire cast iron being taken as 100%.
  • the upper limit of Ce can be 0.03%, or further 0.01%, relative to the entire cast iron being taken as 100%.
  • the lower limit of Ce is not limited in particular as far as it falls in a range in which the effect of serving as a spheroidizing agent is obtainable, the lower limit thereof can be, in actuality however, 0.007%, or further 0.008%, relative to the entire cast iron being taken as 100%.
  • each of these inevitable impurities can be set at 0.02% or less, or further 0.01% or less.
  • the present invention is a manufacturing process for austenitic cast iron, it is equipped with a molten-metal preparation step, a pouring step, and a solidification step that are like those as describe above.
  • the austenitic cast iron according to the present invention be a spheroidal graphite cast iron.
  • auxiliary agent such as an inoculant agent or spheroidizing agent
  • these auxiliary agents have been blended beforehand from the stage of the molten-metal preparation step.
  • a molten metal which comprises the basic elements, previously (i.e., a modifier-free-molten-metal preparation step), and then to be equipped with an auxiliary-agent addition step of blending an auxiliary agent with or adding it to that modifier-free molten metal directly or indirectly.
  • the case of adding an auxiliary agent “directly” is such a case where it is added to the modifier-free molten metal before pouring it into a casting die, and the like.
  • the case of adding or the like an auxiliary agent “indirectly” is such a case where it is charged in a cavity of casting die in advance, and so forth.
  • ladle inoculation inoculating inside casting die
  • wire inoculation wire inoculation
  • auxiliary agent can be carried out at any one of those stages.
  • the auxiliary agent can have any one of powdery shapes, granular shapes, wired shapes, and the like. Note that, although the auxiliary agent can be represented by inoculant agents and spheroidizing agents, it can be additive agents other than these.
  • the inoculant agent can comprise one or more members of Si, Ca, Bi, Ba, Al, Sn, Cu, or R.E., for instance.
  • the following inoculant agents are available: Si—Ca—Bi—Ba—Al-system ones, Si—Ca—Bi—Al-R.E.-system ones, Si—Ca—Al—Ba-system ones, Si—Sn—Cu-system ones, and the like.
  • the addition amount or blended amount of inoculant agent is determined in consideration of the disappearance, the fading phenomenon, and so forth. Hence, it is preferable to set so that the total addition amount becomes from 0.05 to 1%, for instance, when the entire modifier-free molten metal is taken as 100%.
  • the graphite spheroidizing agent can comprise one or more members of Mg, and R.E., for instance.
  • Mg-R.E.-system ones Mg simple substance
  • R.E. simple substances such as mish metal (or Mm)
  • Ni—Mg-system ones Fe—Si—Mg-system ones, and the like.
  • the addition amount or blended amount of spheroidizing agent is also determined in consideration of the disappearance, the fading phenomenon, and so forth.
  • a spheroidizing agent so that a residual Mg content (that is, a content of Mg that remains in a prepared cast iron) becomes from 0.01 to 0.1%, more preferably, from 0.03 to 0.08%, when the entire modifier-free molten metal is taken as 100%.
  • the austenitic cast product according to the present invention is members with desirable configuration that comprise the above-described austenitic cast iron according to the present invention, it is needless to say that their configurations, wall thicknesses, and the like, do not matter at all.
  • the base is a stable austenite phase.
  • the present inventors had ascertained already that it is possible to obtain desired spheroidal graphite cast irons by adjusting the addition method of an auxiliary agent or the addition timing appropriately.
  • a base structure according to the present invention comprises an austenite phase of Fe.
  • a eutectic structure according to the present invention is graphite.
  • the austenitic cast iron according to the present invention can also comprise a spheroidal graphite cast iron.
  • the structure of spheroidal graphite cast iron is indexed by means of a spheroidized proportion of graphite and the number of graphite particles in general.
  • actual austenitic cast products that are good in terms of characteristics exhibit such a spheroidized proportion of graphite, which crystallized or precipitated in the base, as 70% or more, 75% or more, 80% or more, or further 85% or more.
  • the greater the number of graphite particles that have crystallized or precipitate is, themore desirable it is.
  • the number of graphite particles whose particle diameter is 10 ⁇ m or more can be 50 pieces/mm 2 or more, 75 pieces/mm 2 or more, or further 100 pieces/mm 2 or more.
  • the number of graphite particles whose particle diameter is 5 ⁇ m or more can be 150 pieces/mm 2 or more, 200 pieces/mm 2 or more, 250 pieces/mm 2 or more, or further 300 pieces/mm 2 or more. Note that it is preferable that spheroidal graphite can be dispersed within base very finely.
  • the spheroidized proportion of graphite can be measured by means of “G5502 10.7.4” as per JIS or the spheroidized-graphite-proportion judgment testing method as per old JIS “5502” (or the NIK method).
  • the number of graphite particles can be measured by means of counting the number of graphite particles per unit area.
  • the austenitic cast iron according to the present invention is excellent in terms of strength, toughness, workability and the like in ordinary-temperature region, but also it is excellent in terms of heat resistance such as highly resistant to oxidation and high-temperature proof stress.
  • the austenitic cast product according to the present invention that comprises this cast iron is suitable for exhaust-system component parts for automobile, and so forth.
  • the housings of turbocharger, exhaust manifolds, catalyst cases, and so on This is because not only these component parts are always exposed in high-temperature environments that result from high-temperature exhaust gases, but also they are exposed to the sulfur oxides, nitrogen oxides etc. in the exhaust gases.
  • the austenitic cast product according to the present invention is not limited to members that are made use of in such high-temperature region. It is natural that it is utilizable in such members as well that are made use of in ordinary-temperature region or warm region. In particular, since the austenitic cast product according to the present invention can be manufactured at lower cost than conventional ones, the range of its utilization can also be expanded. Moreover, the field of utilization is not limited to the field of automobiles and the field of engines, and the austenitic cast product according to the present invention can be utilized for various kinds of members, too.
  • Raw materials which included at least one or more members of C, Si, Cr, Ni, Mn and Cu (i.e., basic elements) and the balance of Fe, were blended and mixed variously, and they were air melted with a high-frequency furnace, thereby obtaining 47-kg molten metals (i.e. , a molten-metal preparation step).
  • molten metals were poured into a casting die (e.g., sand die) that had been made ready in advance (i.e., a pouring step). On this occasion, they were tapped at about 1,550° C., and were poured at about 1,450° C.
  • the after-pouring molten metals were solidified by natural cooling (that is, in a state of as cast), thereby obtaining test specimens with said configuration (or cast products) (i.e., a solidification step).
  • an auxiliary agent such as an inoculant agent and spheroidizing agents
  • the addition of the inoculant agent was carried out by adding “CALBALLOY” (containing Si—Ca—Al—Ba) produced by OSAKA SPECIAL ALLOY Co., Ltd. in an amount of 0.2% by mass with respect to the modifier-free molten metals being taken as 100%.
  • the addition of the spheroidizing agents was carried out by adding the following to the modifier-free molten metals: an Mg simple substance in an amount of 4% by mass; R.E.
  • the casting die being used herein was a sand die whose size was 50 mm in width ⁇ 180 mm in overall length, and from which a stepped plate-shaped cast product was obtainable, stepped plate-shaped cast product whose height (or thickness) changed in five stages in the following order: (i) 50 mm (50 mm in length) ⁇ (ii) 25 mm (45 mm in length) ⁇ (iii) 12 mm (40 mm in length) ⁇ (iv) 5 mm (25 mm in length) ⁇ 3 mm (20 mm in length).
  • type-“B” “Y”-shaped blocks as per JIS were prepared by means of mold casting, and then ⁇ 6 round rod test specimens were prepared from the rectangular vertical cross-sectional part of the resulting “Y”-shaped blocks.
  • test samples e.g., Nos. 1-1 through 1-5 having different blended compositions were manufactured by means of the aforementioned manufacturing process. Samples, which were collected from a section of the respective test specimens with 5-mm thickness, were subjected to the following analyses.
  • FIG. 1 illustrates an analyzed diagram (or XRD) in which the respective samples were analyzed by X-ray diffraction.
  • XRDs on representative cast irons which have been said to be austenitic cast irons (e.g., Reference Examples: R1 and R2), are also illustrated on FIG. 1 all together.
  • austenite proportions which were found based on those XRDs, are also shown in Table 1 all together.
  • Ni eq and Cr eq that are referred to in the present invention were calculated from the Fe-base composition of each of the samples, and were then shown in Table 1A. Each of those Ni eq and Cr eq were plotted on the correlation diagram that is illustrated in FIG. 2 .
  • Test Specimen Nos. 1-1 through 1-5 are designated with ⁇ marks.
  • the representative conventional cast irons e.g., R3: D-5S, and R4: D-2) were designated with ⁇ marks.
  • Raw materials which included at least one or more members of C, Si, Cr, Ni, Mn and Cu (i.e., basic elements) and the balance of Fe, were blended and mixed variously, and they were air melted with a high-frequency furnace, thereby obtaining 47-kg stock molten metals (i.e., a modifier-free-molten-metal preparation step).
  • a modifier-free-molten-metal preparation step Each of these modifier-free molten metals was poured into a casting die (e.g., sand die) that had been made ready in advance (i.e., a pouring step).
  • Test Specimen Nos. 2-1 through 2-13 having different blended compositions were manufactured by means of the aforementioned manufacturing process. Samples, which were collected from a section of the respective test specimens with 12-mm thickness, were subjected to the following analyses.
  • the number of graphite's particles was found by counting those whose particle diameters were 10 ⁇ m or more in a 4.8-mm 2 area.
  • Ni eq and Cr eq were calculated from the analyzed composition of each of the entire samples, and were then shown in Table 2B. Each of these Ni eq and Cr eq was plotted with “+” marks on the structural diagram in FIG. 2 in a superimposed manner. The C s was treated in the same manner as in the case of First Test.
  • FIG. 3 An XRD that evidences this issue is illustrated in FIG. 3 .
  • the XRD in FIG. 3 was obtained by subjecting the 5-mm-thickness section and 12-mm-thickness section of Test Specimen No. 2-2 to X-ray diffraction.
  • test specimens being directed to the present invention had strength (or hardness) and heat-resistance strength that were equivalent to or more than those of conventional austenitic cast irons (e.g., Reference Examples R3 and R4).
  • test specimens being directed to the present invention exhibited larger proof stresses at 800° C., which matter in view of practical perspective, than did the conventional austenitic cast irons.
  • the austenitic cast iron being directed to the present invention has high heat resistance that is equivalent to or more than those of conventional ones.
  • Test Specimen No. 3-1 An inoculant agent being added in Test Specimen No. 3-1 was “TOYOBARON BIL,” namely, 74.18Si-1.23Ca-0.55Ba-0.72Bi-0.51Al—Fe, produced by TOYO DENKA Co., Ltd. This one was added in a proportion of 0.2% by mass with respect to the modifier-free molten metal.
  • used spheroidizing agents were the following: an Mg simple substance in an amount of 4% by mass; R.E. (e.g., misch metal) in an amount of 1.8% by mass; and an Sb simple substance in an amount of 0.005% by mass; and those were added in the respective proportions with respect to the modifier-free molten metals. Note that the amount of Mg was great because the disappearance and the like were considered.
  • An implant agent being used in Test Specimen No. 3-2 was said “TOYOBARON BIL.” This one was added in a proportion of 0.4% by mass with respect to the modifier-free molten metal.
  • spheroidizing agents the following were added to the modifier-free molten metal: Mg in an amount of 4% by mass; R.E. (e.g. , misch metal) in an amount of 1.8%; and Sb in an amount of 0.0005% by mass.
  • the added Sb amount differed from that in Test Specimen No. 3-1.
  • FIG. 4A and FIG. 4B The optical-microscope photographs of the respective samples are shown in FIG. 4A and FIG. 4B .
  • #1 through #5 in the diagrams indicate that the structural photographs show the samples' sections that were prepared by dividing the samples into five sections evenly from the sand die's upper-face side to the lower-face side.
  • #1 specifies the structure in the vicinity of the uppermost face
  • #5 specifies the structure in the vicinity of the lowermost face. Note that the structural photographs were taken after etching the samples' faces with 3% nital.
  • the austenitic cast iron (or cast product) according to the present invention excels in terms of mechanical characteristics, and moreover excels in terms of post-casting mechanical workabilities as well due to the moderate hardness.
  • compositions of the basic elements, and the types and addition amounts of the auxiliary agents were changed, the others were set in the same manner as those of Second Test and then twelve types of test specimens (i.e., Test Specimen Nos. 4-1 through 4-12) were manufactured.
  • auxiliary agents such as an inoculants agent and spheroidizing agents
  • the added inoculant agent was “TOYOBARON BIL,” namely, 74.18Si-1.23Ca-0.55Ba-0.72Bi-0.51Al—Fe, produced by TOYO DENKA Co., Ltd. This one was added in a proportion of 0.4% by mass with respect to the modifier-free molten metals.
  • the addition of the spheroidizing agents was carried out by adding the following to the modifier-free molten metals: an Mg simple substance in an amount of 4% by mass; R.E. (e.g.
  • Test Specimen Nos. 4-1 through 4-12 which were manufactured by means of the aforementioned manufacturing process but which had different blended compositions, were subjected to the following analyses.
  • Ni eq and Cr eq were calculated from the analyzed composition of each of the entire samples, and were then shown in Table 4B. Each of these Ni eq and Cr eq was plotted with “ ⁇ ” marks on the structural diagram in FIG. 2 in a superimposed manner. The C s was treated in the same manner as in the case of First Test.
  • a magnet did not react to their 25-mm-thickness and 12-mm-thickness sections, and accordingly it was ascertained that they were free from magnetism. That is, being free from magnetism means that ferrite, namely, a magnetic substance, does not exist, and consequently it is possible to speculate that they comprised an austenite single phase.
  • Niresist FCDA-NiMn137 as per JIS
  • FCDA-NiMn137 FCDA-NiMn137 as per JIS
  • Test Specimen Nos. 4-3, 4-7, 4-8, 4-11 and 4-12 namely, the present austenitic cast irons, had a thermal-fatigue life that was extended far greater than those of Test Specimen Nos. R5 and R6 and ferritic cast irons. Moreover, even when their thermal-fatigue lives were compared with those of general austenitic cast irons, the former was equivalent to or more than the latter.
  • compositions of the basic elements, and the types and addition amounts of the auxiliary agents were changed, the others were set in the same manner as those of Fourth Test and then twelve types of Test Specimen Nos. 5-1 through 5-12 were manufactured.
  • auxiliary agents such as an inoculant agent and a spheroidizing agent
  • the added inoculant agent was “TOYOBARON BIL,” namely, 74.18Si-1.23Ca-0.55Ba-0.72Bi-0.51Al—Fe, produced by TOYO DENKA Co., Ltd. This one was added in a proportion of 0.4% by mass with respect to the modifier-free molten metals.
  • spheroidizing agent a spheroidizing agent that had the following in the following contained amounts was made use of: 4%-by-mass Mg simple substance; and 1.8%-by-mass R.E.
  • the addition was carried out by adding it to the modifier-free molten metals so that the Mg residual amount became from 0.04 to 0.05% by mass with respect to the 100% modifier-free molten metals and the Sb-simple-substance residual amount became 0.0005% by mass with respect to them.
  • Test Specimen Nos. 5-1 through 5-12 which were manufactured by means of the aforementioned manufacturing process but which had different blended compositions, were subjected to the following analyses.
  • FIG. 9 illustrates an analyzed diagram (or XRD) in which samples that were collected from the 25-mm-thickness section of some of the test specimens were subjected to an X-ray diffraction analysis.
  • FIG. 10 illustrates correlations between linear expansion coefficients and temperatures that were measured for the other some of the test specimens.
  • Ni eq and Cr eq were calculated from the analyzed composition of each of the entire samples, and were then shown in Table 4B. Each of these Ni eq and Cr eq was plotted with “ ⁇ ” marks on the structural diagram in FIG. 2 in a superimposed manner. The C s was treated in the same manner as in the case of First Test.
  • the oxidation resistance was evaluated by measuring the oxidized weight reduction or oxidized weight increment based on “Z 2282” as per JIS.
  • a variety of test specimens with ⁇ 20 ⁇ 20 mm which were collected from type-“B” and type-“D” “Y”-shaped blocks as per JIS that were prepared by means of mold casting, were first retained in an air atmosphere at 800° C. for 100 hours. Iron balls whose shot spherical diameter was 0.4 mm were then projected to the test specimens that were after this heat treatment, and the projection was carried out until oxide layers on their surfaces disappeared.
  • the oxidized weight increment or oxidized weight decrement was each of the test specimens' mass increment or mass decrement per unit area.
  • the oxidized weight increment was obtained by deducting amass of each of the test specimens before the heat treatment from another mass of the test specimen immediately after the aforementioned heat treatment (or before being shot).
  • the oxidized weight decrement was obtained by deducting a mass of each of the test specimens after being shot from another mass of the test specimen immediately after the aforementioned heat treatment (or before being shot).
  • FIG. 11 illustrates the oxidized weight reductions of the respective test specimens with a bar graph. Note that, in FIG. 11 , the oxidized weight reductions of some of the test specimens that are shown in Tables 4A and 4B are also illustrated all together in addition to the oxidized weight reductions of the test specimens that are shown in Tables 5A and 5B.
  • FIGS. 12( a ) and ( b ), and FIGS. 13( a ) and ( b ) illustrate results of examining correlations between the contained amounts (or addition amounts) of Ni, Mn, Cr and Cu (i.e., the basic elements that are directed to the austenitic cast iron according to the present invention) and oxidized reductions on the basis of Fe-3% C-4% Si-“a”% Ni-“b”% Mn-“c”% Cr-“d”%Cu (% by mass).
  • the toughness was evaluated by carrying out a test based on “Z 2242” as per JIS and then measuring the Charpy-impact values of the respective test specimens.
  • the Charpy-impact values of the respective test specimens were measured under room temperature using V-notched test specimens with 10 ⁇ 10 ⁇ 50 mm that were collected from type-“B” and type-“D” “Y”-shaped blocks as per JIS.
  • FIG. 14 illustrates the Charpy-impact values of the respective test specimens with a bar graph. Note that, in FIG. 14 , the Charpy-impact values of some of the test specimens that are shown in Tables 4A and 4B are also illustrated all together in addition to the Charpy-impact values of the test specimens that are shown in Tables 5A and 5B.
  • FIG. 15 illustrates correlations between the Charpy-impact values of the respective test specimens, which are shown in FIG. 14 , and the contained amounts of Cr in the respective test specimens.
  • ⁇ 6-mm round-bar test specimens which were collected from type-“A” “Y”-shaped blocks as per JIS that were prepared by means of mold casting, were used for the measurements of proof stress, tensile strength, elongation, reduction of area and Young's modulus.
  • FIG. 16 illustrates the 0.2% proof stress and fracture elongation of each of the test specimens with a bar graph.
  • those of some of the test specimens that are shown in Tables 4A and 4B are also illustrated all together in addition to those of the test specimens that are shown in Tables 5A and 5B.
  • FIG. 17 illustrates correlations between the respective test specimens' rupture elongation and their contained Cr amount or contained Cu amount.
  • FIG. 18 illustrates the hardness (Hv at 20 kgf) of each of the above-described test specimens with 5-mm plate thickness with a bar graph.
  • FIG. 20 illustrates results of the relative evaluation on the molten-metal running properties with a bar graph.
  • the area of the molten-metal running portion being exhibited by Test Specimen Nos. 5-1, 5-9 and 4-3 that is, the test specimens that were considered showing the most satisfactory molten-metal running property, was taken as “1,” and then the molten-metal running portions of the other test specimens were evaluated relatively to that of the formers.
  • FIG. 24 illustrates results of evaluating the shrinkage magnitudes of the respective test specimens relatively while taking the shrinkage magnitude of Test Specimen No. R3 as “1.”
  • the heating-temperature width was limited to from 150 to 800° C., and then an average linear expansion coefficient of each of the test specimens was found. The resulting outcomes are illustrated in FIG. 27 .
  • Test Specimen No. 5-5's correlation diagram between temperatures and linear expansion coefficients showed a gentle form, which was similar to those of other Test Specimen No. 4-3, No. R3 and No. R4 that comprised an austenite phase, up to around 910° C. at least; and the linear expansion coefficient did not change abruptly unlike the linear expansion coefficient of Test Specimen No. R6 comprising a ferrite phase that did so contrarily in a specific temperature zone (e.g., at around 750° C.). It was ascertained from these facts as well that the cast irons according to Test Specimen Nos. 5-1 through 5-12 are austenitic cast irons that virtually comprise an austenite single phase, respectively.
  • test specimens turn into an austenite single phase even when the Ni equivalents are less in a range where the Cr equivalents falls in a range of from 7 to 9, because of the following facts: NiMn137 is not an austenite single phase at ordinary temperature; and all of the test specimens (e.g., the test specimens that are present below the dotted line in FIG. 2 ) turned into an austenite phase, respectively, and such test specimens were speculated to be less likely to turn into an austenite single phase than is NiMn137 on the Schaeffler's structural diagram.
  • Mn and Ni make a relationship, namely, 0.5:1, with respect to an Ni equivalent in the Schaeffler's structural diagram; consequently, it is possible to speculate that Test Specimen No. 5-12 keeps being an austenite single phase even when the Mn content is reduced from “7.5” to “0.1” and the Ni content is increased from “8.5” to “12.2,” for instance, because there is not any change in the Ni equivalent.
  • Test Specimen No. 5-12 keeps being an austenite single phase even when the Mn content is reduced from “7.5” to “0.1” and the Ni content is increased from “8.5” to “12.2,” for instance, because there is not any change in the Ni equivalent.
  • the Mn content namely, a factor of raising hardness, can be decreased, it is possible to lower the hardness of austenitic cast iron.
  • the contained amount of Cr can be from 0.5 to 2% by mass, or further from 0.5 to 1.5% by mass approximately, in order to secure the oxidation resistance and toughness that can be equivalent to or more than those of conventional austenitic cast irons (e.g., Test Specimen Nos. R3 and R4).
  • any one of the cast irons according to Test Specimen Nos. 5-1 through 5-12 had high-temperature strength (e.g., 0.2%proof stress and fracture elongation at 800° C.) that was the same or more than those of conventional austenitic cast irons (e.g., Test Specimen Nos. R3 through R5) and ferritic cast iron (e.g., Test Specimen No. R6).
  • high-temperature strength e.g. 0.2%proof stress and fracture elongation at 800° C.
  • ferritic cast iron e.g., Test Specimen No. R6
  • the austenitic cast irons' fracture elongation at high temperature was improved bymeans of increasing the contained amount of Cr, it became a virtually saturated state when that contained amount was 2.5% by mass approximately.
  • the austenitic cast irons' fracture elongation at high temperature was decreased sharply by means of increasing the contained amount of Cu.
  • the upper limit of the contained amount of Cr can be 3% by mass or less, or further 2.5% by mass, approximately; and it is preferable that the upper limit of the contained amount of Cu can be 2% by mass approximately.
  • the hardness of test specimen is affected by the additive elements and plate thicknesses. That is, it becomes such a tendency that the hardness of test specimen rises when adding Cr or Mn. On the contrary, it becomes such an opposite tendency that the hardness of test specimen declines when adding Ni or Cu. From these facts, it is appreciated that an austenitic cast iron with desired hardness is obtainable by means of the selection of these additive elements and the adjustment of their addition amounts.
  • the resulting hardness is affected by the thickness of test specimen (or cast product) as well.
  • the influence of the additive elements is great at sections with smaller plate thicknesses, it was appreciated that the greater those plate thicknesses become the smaller the influence of any one of the additive elements becomes and then the hardness shows such a tendency that it converges to that of a test specimen comprising a datum composition.
  • any one of Test Specimen Nos. 5-1 through 5-12 was superior to a conventional austenitic cast iron (e.g., Test Specimen No. R5) in terms of the molten-metal running property.
  • the austenitic cast irons which are directed to the present invention, were superior to another conventional austenitic cast iron (e.g., Test Specimen No. R3) in terms of the molten-metal running property, because their molten-metal running properties were very favorable, that is, they were about 1 in all of them, excepting Test Specimen No. 5-11, regardless of being evaluated relatively.
  • Test Specimen Nos. 5-5 and 5-6 were excellent materials, because they exhibited moderate hardness and were good in terms of the oxidation resistance despite their contents of Ni that were less.
  • compositions of the basic elements, and the types and addition amounts of the auxiliary agents were changed, the others were set in the same manner as those of Second Test and then six types of Test Specimen Nos. 6-1 through 6-6 were manufactured. Note that the addition of the auxiliary agents, such as an ioculant agent and a spheroidizing agent, was also carried out when casting the respective test specimens.
  • the added inoculants agent was “TOYOBARON BIL,” namely, 74.18Si-1.23Ca-0.55Ba-0.72Bi-0.51Al—Fe, produced by TOYO DENKA Co., Ltd. This one was added in a proportion of 0.4% by mass with respect to the modifier-free molten metals.
  • a spheroidizing agent which had an Mg simple substance and R.E. (e.g., misch metal) in a contained amount of 4% by mass and 1.8% by mass respectively, was made use of; and the addition was carried out to the stock molten metals so that a residual amount of Mg became from 0.04 to 0.06% by mass and a residual amount of Sb simple substance became 0.0005% by mass with respect to the 100% stock molten metals.
  • Mg simple substance and R.E. e.g., misch metal
  • Test Specimen Nos. 6-1 through 6-6 which were manufactured by means of the aforementioned manufacturing process but which had different blended compositions, were subjected to the following analyses.
  • gases that were gasified by means of high-frequency combustion were quantified by infrared absorption spectrophotometry using an analyzing apparatus that was produced by LECO Corporation, and thereby 0 was quantified by infrared absorption spectrophotometry and N was quantified by thermal conductivity method.
  • the oxidized weight increment or oxidized weight decrement was each of the test specimens' mass increment or mass decrement per unit area.
  • the oxidized weight increment was obtained by deducting amass of each of the test specimens before the heat treatment from another mass of the test specimen immediately after the aforementioned heat treatment (or before being shot).
  • the oxidized weight decrement was a value that was obtained by dividing a deducted value, which was obtained by deducting a mass of each of the test specimens after being shot from another mass of the test specimen immediately after the aforementioned heat treatment (or before being shot), with a surface area of the test specimen.
  • Table 6B The thus found oxidized weight increments and oxidized weight decrements are shown in Table 6B.
  • the oxidized weight reduction and oxidized weight increment were measured for each of the test specimens. Not only the results are shown in Table 6C but also the oxidized weight reductions of the respective test specimens are illustrated with a bar graph in FIG. 29 . Note that the oxidized weight reductions of the Test Specimen Nos. R3, R4, R5 and R7 that comprised conventional cast irons are also shown all together in Table 6A, Table 6B and FIG. 29 for comparison, in addition to those of present Test Specimen Nos. 6-1 through 6-6. Incidentally, the oxidized weight reductions that are given in Table 6A, Table 6B and FIG. 29 are averaged values of their twice-measured values, and the oxidized weight increments are averaged values of their thrice-measured values.
  • the proof stress, tensile strength and elongation were measured similarly for each of the test specimens. Not only the results are shown in Table 6C but also the proof stresses, tensile strengths and elongations of the respective test specimens are illustrated with a bar graph in FIGS. 30 through 32, respectively.
  • the proof stresses, tensile strengths and elongations of the Test Specimen Nos. R3, R4, R5 and R7 that comprised conventional cast irons are also shown all together for comparison, in addition to those of present Test Specimens Nos. 6-1 through 6-6.
  • the proof stresses, tensile strengths and elongations that are given in Table 6A, Table 6B and FIGS. 30 through 32 are averaged values of their thrice-measured values.
  • each of the test specimens' temperature was fluctuated between 150° C. and 800° C. repeatedly while setting the constrained ratio of those test specimens at 100%, thereby examining the number of cycles at which stresses that acted on the test specimens lowered by 10%, the number of cycles at which they lowered by 25%, and the number of cycles at which the test specimens fractured apart, respectively.
  • a linear expansion coefficient of each of the test specimens was found. This linear expansion coefficient was found by measuring a change of each of the test specimens in the length when the test specimens' temperature was changed from 40° C. and up to 900° C. at a temperature-increment rate of 3° C/min in the presence of nitrogen atmosphere (e.g., 0.05 MPa). A configuration of the test specimens that were used for this measurement was adapted into a squared-column shape with 3 mm ⁇ 3 mm squared section and 15 mm in length. The respective test specimens had been annealed in advance by heating them to 950° C. or more in air. These results are given in Table 6C.
  • Linear Expansion Coefficient means average thermal expansion coefficients from 40 and up to 900° C., and that these averaged linear expansion coefficients are values that were obtained by further averaging their twice-measured values (averaged linear expansion coefficients) being found for the respective test specimens.
  • the austenitic cast irons (or cast products) according to the present example was good not only in terms of mechanical characteristics but also in terms of machinability, because the hardness was stabilized as from 200 Hv to 300 Hv approximately.
  • the oxidized weight reduction was 30 mg/cm 2 or less approximately when the heating temperature was 750° C.; and it was as small as 50 mg/cm 2 or less approximately when the heating temperature was 800° C.; in any one of Test Specimen Nos. 6-1 through 6-6. It is understood that the austenitic cast irons according to the present example were good in terms of the oxidation resistance, because any one of the oxidized weight reductions was 100 mg/cm 2 or less approximately even in the case where the heating temperature was 850° C.
  • the Cr content or the Ni content affects greatly the suppression of the oxidized weight reduction, that is, the improvement of the oxidation resistance, when comparing Test Specimen No. 6-1 with Test Specimen No. 6-5 or comparing Test Specimen No. 6-5 with Test Specimen No. 6-6, for instance.
  • Test Specimen No. 6-3 in which both of the Cr content and Ni content were great, it was ascertained that the suppression of the oxidized weight reduction was so remarkable as being at the same level as that in Test Specimen No. R7.
  • any one of the thermal-fatigue lives of Test Specimen Nos. 6-1 through 6-6 were equivalent to or more than those of Test Specimen No. R3 or Test Specimen No. R4, namely, those of general austenitic cast irons.
  • the test specimens that contained an appropriate amount of Cu had a longer thermal-fatigue life rather than those that did not.

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  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Supercharger (AREA)
  • Exhaust Silencers (AREA)
  • Heat Treatment Of Steel (AREA)
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110290384A1 (en) * 2009-02-09 2011-12-01 Hokkou Metal Industry Co., Ltd. High-manganese spheroidal graphite cast iron
US20130048906A1 (en) * 2011-08-30 2013-02-28 Third Millennium Metals, Llc Iron-carbon compositions
KR101365685B1 (ko) 2011-12-13 2014-02-25 부산대학교 산학협력단 오스테나이트계 저-니켈 합금주철
US20160138139A1 (en) * 2013-09-06 2016-05-19 Toshiba Kikai Kabushiki Kaisha Spheroidizing treatment method for molten metal of spheroidal graphite cast iron
US9567657B2 (en) 2010-05-21 2017-02-14 Kabushiki Kaisha Toyota Jidoshokki Austenitic cast iron, austenitic-cast-iron cast product and manufacturing process for the same
RU2720271C1 (ru) * 2019-11-28 2020-04-28 Федеральное государственное бюджетное образовательное учреждение высшего образования "Ярославский государственный технический университет" ФГБОУВО "ЯГТУ" Высокопрочный легированный антифрикционный чугун
EP3604561A4 (en) * 2017-03-29 2020-08-19 I2C Co., Ltd. PROCESS FOR THE PRODUCTION OF SPHERICAL GRAPHIC CAST IRON PRESSURE CAST INCLUDING ULTRAFINE SPHERICAL GRAPHITE, AND SPHEROIDIZING TREATMENT AGENT

Families Citing this family (8)

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Publication number Priority date Publication date Assignee Title
JP5475380B2 (ja) * 2009-09-24 2014-04-16 株式会社豊田自動織機 オーステナイト系鋳鉄とその製造方法およびオーステナイト系鋳鉄鋳物
JP5618065B2 (ja) * 2010-08-04 2014-11-05 Ｊｆｅスチール株式会社 球状黒鉛鋳鉄用Ｂｉ系接種剤およびこれを用いる球状黒鉛鋳鉄の製造方法
CN102191423B (zh) * 2011-04-14 2012-12-12 湖南长高新材料股份有限公司 一种适应于耐磨铁基合金的稀土-合金复合变质剂
JP2014237875A (ja) * 2013-06-07 2014-12-18 株式会社木村鋳造所 ワイヤー供給装置
RU2583225C1 (ru) * 2014-12-09 2016-05-10 Открытое акционерное общество "ГАЗ" (ОАО "ГАЗ") Высокопрочный хладостойкий чугун
RU2624543C1 (ru) * 2016-10-10 2017-07-04 Юлия Алексеевна Щепочкина Чугун
RU2625191C1 (ru) * 2016-10-10 2017-07-12 Юлия Алексеевна Щепочкина Чугун
RU2657957C1 (ru) * 2017-11-20 2018-06-18 Юлия Алексеевна Щепочкина Чугун

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20010023717A1 (en) * 1999-04-28 2001-09-27 Yutaka Kawano Stainless spheroidal carbide cast iron
US20040151612A1 (en) * 2003-01-30 2004-08-05 Osaka Prefecture High manganese cast iron containing spheroidal vanadium carbide and method for making thereof
US20060191604A1 (en) * 2003-07-18 2006-08-31 Kenji Itoh Austenite heat-resistant spheroidal graphite cast iron

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB801698A (en) * 1955-08-29 1958-09-17 Cie De Pont A Mousson Improvements in or relating to spheroidal graphite cast irons
JPS5417683B2 (ja) * 1972-03-15 1979-07-02
DE2646276C3 (de) * 1976-10-14 1980-01-17 Goetze Ag, 5093 Burscheid Verfahren zur Herstellung von auf Verschleiß beanspruchten Maschinenteilen aus austenitischen Gußeisenlegierungen
JPS5658945A (en) * 1979-10-18 1981-05-22 Hitachi Zosen Corp High toughness nodular graphite cast iron
JPS6012417B2 (ja) * 1981-08-13 1985-04-01 石川島播磨重工業株式会社 耐熱性球状黒鉛オ−ステナイト鋳鉄
CN85100066A (zh) * 1985-04-01 1986-07-09 清华大学 低镍奥氏体球墨铸铁
JPS62210256A (ja) * 1986-03-10 1987-09-16 Nippon Denso Co Ltd 内燃機関用燃料供給装置
JPS63210256A (ja) * 1987-02-27 1988-08-31 Aisin Takaoka Ltd 振動減衰能が大きいオ−ステナイト鋳鉄
JPH0243342A (ja) * 1988-08-03 1990-02-13 Kubota Ltd 高硬度オーステナイト鋳鉄
JP3456635B2 (ja) * 1999-04-28 2003-10-14 株式會社三共合金鑄造所 球状炭化物鋳鉄

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20010023717A1 (en) * 1999-04-28 2001-09-27 Yutaka Kawano Stainless spheroidal carbide cast iron
US20040151612A1 (en) * 2003-01-30 2004-08-05 Osaka Prefecture High manganese cast iron containing spheroidal vanadium carbide and method for making thereof
US20060191604A1 (en) * 2003-07-18 2006-08-31 Kenji Itoh Austenite heat-resistant spheroidal graphite cast iron

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110290384A1 (en) * 2009-02-09 2011-12-01 Hokkou Metal Industry Co., Ltd. High-manganese spheroidal graphite cast iron
US8585837B2 (en) * 2009-02-09 2013-11-19 Hokkou Metal Industry Co., Ltd. High-manganese spheroidal graphite cast iron
US9567657B2 (en) 2010-05-21 2017-02-14 Kabushiki Kaisha Toyota Jidoshokki Austenitic cast iron, austenitic-cast-iron cast product and manufacturing process for the same
US20130048906A1 (en) * 2011-08-30 2013-02-28 Third Millennium Metals, Llc Iron-carbon compositions
KR101365685B1 (ko) 2011-12-13 2014-02-25 부산대학교 산학협력단 오스테나이트계 저-니켈 합금주철
US20160138139A1 (en) * 2013-09-06 2016-05-19 Toshiba Kikai Kabushiki Kaisha Spheroidizing treatment method for molten metal of spheroidal graphite cast iron
EP3604561A4 (en) * 2017-03-29 2020-08-19 I2C Co., Ltd. PROCESS FOR THE PRODUCTION OF SPHERICAL GRAPHIC CAST IRON PRESSURE CAST INCLUDING ULTRAFINE SPHERICAL GRAPHITE, AND SPHEROIDIZING TREATMENT AGENT
RU2720271C1 (ru) * 2019-11-28 2020-04-28 Федеральное государственное бюджетное образовательное учреждение высшего образования "Ярославский государственный технический университет" ФГБОУВО "ЯГТУ" Высокопрочный легированный антифрикционный чугун

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EP2184372B1 (en) 2013-10-16
ES2441598T3 (es) 2014-02-05
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EP2184372A4 (en) 2011-12-21
JP5384352B2 (ja) 2014-01-08

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