EP0076701B1 - Heat-resistant spheroidal graphite cast iron - Google Patents

Heat-resistant spheroidal graphite cast iron Download PDF

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Publication number
EP0076701B1
EP0076701B1 EP19820305306 EP82305306A EP0076701B1 EP 0076701 B1 EP0076701 B1 EP 0076701B1 EP 19820305306 EP19820305306 EP 19820305306 EP 82305306 A EP82305306 A EP 82305306A EP 0076701 B1 EP0076701 B1 EP 0076701B1
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EP
European Patent Office
Prior art keywords
cast iron
spheroidal graphite
graphite cast
content
irons
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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.)
Expired
Application number
EP19820305306
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German (de)
English (en)
French (fr)
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EP0076701A2 (en
EP0076701A3 (en
Inventor
Yoshimasa Tanaka
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.)
Nissan Motor Co Ltd
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Nissan Motor Co Ltd
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Publication of EP0076701A3 publication Critical patent/EP0076701A3/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
    • C22C37/04—Cast-iron alloys containing spheroidal graphite

Definitions

  • This invention relates to a spheroidal graphite cast iron which has a high resistance of oxidation at high temperatures.
  • a spheroidal graphite cast iron as a structural material in an apparatus or device which is operated at high temperatures.
  • the turbine housing of an exhaust gas turbocharger is usually made of a spheroidal graphite cast iron.
  • a high silicon spheroidal graphite cast iron having a ferrite matrix is employed as the material of the turbine housing.
  • such a spheroidal graphite cast iron contains 3.0 to 3.4 wt% of C, 3.65 to 4.10 wt% of Si, up to 0.6 wt% of Mn, up to 0.5 wt% of Ni, 0.5 to 0.7 wt% of Mo and up to 0.07 wt% of Cr.
  • Spheroidal graphite cast irons of this class are relatively low in price and are generally satisfactory in mechanical properties, but have an unsatisfactorily low resistance to oxidation at high temperatures.
  • a spheroidal graphite cast iron of this class contains up to 3.0 wt% of C, 1.5 to 3.0 wt% of Si, 0.70 to 1.25 of Mn, 18.0 to 22.0 wt% of Ni and 1.75 to 2.75 wt% of Cr, and another cast iron of the. same class contains up to 2.4 wt% of C, 1.0 to 2.8 wt% of Si, up to 1.0 wt% of Mn, 34.0 to 36.0 wt% of Ni and 2.0 to 3.0 wt% of Cr.
  • cast irons of this class are very costly due to their Ni content, and, further such cast irons are relatively low in strength (e.g. about 40 kgf/mm 2 in tensile strength and about 20 kgf/mm 2 in 0.2% proof stress) and also in toughness (e.g. below 10% in elongation).
  • the present invention provides a heat-resistant spheroidal graphite cast iron which consists of not more than 3.4 wt% of C, 3.5 to 5.5 wt% of Si, not more than 0.6 wt% of Mn, 0.1 to 0.7 wt% of Cr, 0.3 to 0.9 wt% of Mo, not more than 0.1 wt% of a spheroidizing agent and the balance of Fe plus impurities.
  • the matrix of this cast iron is principally ferrite.
  • the C content of the cast iron of the invention is not less than 1.7 wt% and the Cr content is not less than 0.25 wt%.
  • a spheroidal graphite cast iron according to the invention is comparable to, and sometimes better than conventional high silicon spheroidal graphite cast irons in mechanical properties and distinctly superior in resistance to oxidation at high temperatures such as 700-1000°C.
  • the favourably balanced properties of the cast iron of the invention are realized by correlatively specifying the contents of Si and Cr within the above indicated ranges.
  • a spheroidal graphite cast iron of the invention is higher in strength and nearly equivalent in the resistance to oxidation at relatively low temperatures and, as an industrially important factor, can be prepared at a far lower cost.
  • a heat-resistant spheroidal graphite cast iron according to the invention has the composition specified above.
  • the effects of the respective alloying elements and the reasons for the limitations on the amounts of the respective elements are as follows. Throughout the following description, the amounts of the elements in the cast iron are given in percentages by weight.
  • C is an alloying element indispensable to cast iron.
  • the C content is limited to a maximum of 3.4 because the presence of more than 3.4% of C tends to cause crystallization of an excessively large quantity of graphite and a reduction in the strength and toughness of the cast iron.
  • the cast iron becomes inferior in its properties mainly because of insufficiency in the crystallization of graphite and a reduction in the fluidity of the molten metal. In most cases this tendency becomes significant if the C content is less than about 1.7%. Therefore, it is preferred that a spheroidal graphite cast iron according to the invention contains at least 1.7% of C.
  • Si is added to cast iron for the purpose of achieving graphitization.
  • the Si content is specified to be higher than in ordinary spheroidal cast irons with the additional purpose of enhancing the oxidation resistance of the cast iron.
  • Test pieces of the four cast iron samples were kept heated in air at either 600°C or 700°C for a total period of 500 hr, and the thickness of an oxidized scale layer on each test piece was measured at suitable time intervals to estimate the oxidation resistance of each cast iron sample on the basis of the maximum thickness of the scale layer in each sample.
  • the results of these experiments at 600°C and at 700°C are shown in Figs. 1 and 2 of the drawings, respectively. From the curves in Figs. 1 and 2 it is apparent that the oxidation resistance of the cast iron can be enhanced by increasing the content of Si.
  • the content of Si in the cast irons of the present invention is limited within the range from 3.5% to 5.5%.
  • Cr is an alloying element which contributes to reinforcement of the oxidation resistance of the cast iron at high temperatures.
  • the minimum Cr content is set at 0.1 % because the expected effects are insufficient if the Cr content is less than 0.1 %. Since the effect of reinforcing the ferrite matrix augments as the Cr content is increased, it is preferred that the Cr content of the cast irons of the present invention is at least 0.25%.
  • the content of Cr is limited to a maximum of 0.7% because the addition of more than 0.7.% of Cr is liable to deteriorate the workability and other mechanical properties of the cast iron by reason of formation of free carbides.
  • Mo has the effect of reinforcing the ferrite matrix of the cast iron and thereby enhancing the high temperature strength of the cast iron.
  • the expected effect is insufficient if the Mo content is below 0.3%.
  • the Mo content is limited to a maximum of 0.9% because the addition of more than 0.9% of Mo is liable to cause formation of free carbides and to result in a deterioration of the mechanical properties of the cast iron.
  • Mn is an alloying element having a desul- phurizing ability.
  • the content of Mn is limited to a maximum of 0.6% because the presence of an unnecessarily large amount of Mn in the cast iron produces an unwanted effect of stabilizing pearlite in the cast iron.
  • the spheroidizing agent may be freely selected from known spheroidizing agents such as Mg, Ca and Ce for example. It is undesirable to use an unnecessarily large amount of spheroidizing agent because of its unfavourable side-effects. For example, the use of an unduly large amount of Mg, which is a typical spheroidizing agent, has the unwanted effect of stabilizing cementite in the cast iron. Therefore, the amount of the spheroidizing agent is limited to a maximum of 0.1 %.
  • a spheroidal graphite cast iron of the invention contains very small amounts of impurities besides the above described essential alloying elements and Fe. Typical examples of such impurity elements are phosphorus and sulphur. It is preferred that the P content is below 0.1 % because a higher P content is detrimental to the workability, typified by ductility, of the cast iron. Also it is preferred that the S content is below 0.1 % because a higher S content is obstructive to spheroidization of graphite.
  • a spheroidal graphite cast iron of the invention can be prepared by a known method of the preparation of a ferritic spheroidal graphite cast iron.
  • a molten metal of a suitable composition including a spheroidizing agent is allowed to solidify in a mould, and the solidified casting is then subjected to a spheroidizing-ferritizing heat treatment.
  • a spheroidal graphite cast iron has the composition shown in Table 1 below was prepared by a usual method, in which the solidified casting was subjected to a spheroidizing-ferritizing annealing treatment under the conditions shown in Fig. 3 of the drawings. Besides the elements listed in the Table, a small quantity of Mg was used as spheroidizing agent so that the product contained 0.039% of Mg. As shown in Fig. 3, the annealing treatment consisted of heating at 930°C for 2.5 hr, initial lowrate cooling from 930°C to 300°C performed as furnace cooling and subsequent air cooling.
  • Fig. 5 is a photomicrograph (100xmagnification) showing the structure of the cast iron obtained in this way.
  • the structure of this cast iron may be expressed as being a ferrite matrix containing spheroidal cementite and a very small portion of pearlite containing certain carbides therein. That is, the cast iron was a ferritic spheroidal graphite cast iron.
  • Another spheroidal graphite cast iron having the composition shown in Table 1 below was prepared by the same method as described in Example 1. Besides the elements noted in the Table, 0.045% of Mg was present in the product by reason of the use of Mg as spheroidizing .agent. The structure of this cast iron was fundamentally similar to that of the cast iron of Example 1. As can be seen in the Table, substantially the sole difference of the cast iron of Example 2 from that of Example 1 was about a 45% decrease in the Cr content accompanied by a slight decrease in the Mo content.
  • Test pieces cut out of the cast irons of Examples 1 and 2 were subjected to tensile strength tests at ambient temperature and also to oxidation resistance tests at high temperatures.
  • a conventional high nickel spheroidal graphite cast iron (Reference 1) and a conventional ferric spheroidal graphite cast iron (Reference 2) were subjected to the same tests.
  • the compositions of the cast irons of References 1 and 2 are shown in Table 1 below.
  • the cast irons of the References 1 and 2 contained 0.080% of Mg and 0.070% of Mg, respectively.
  • Each test piece for the tensile strength test was 50 mm in gauge length, 70 mm in the length of the straight portion and 7 mm in the diameter of the straight portion, and the straining speed at the test was 20% min.
  • the result of the test is presented in Table 1.
  • the oxidation resistance test was carried out at 750°C, 850°C and 950°C. At each temperature the test pieces were kept heated in air for 200 hr, and the oxidation resistance of each sample was estimated from the maximum thickness of an oxidised scale layer on each test piece. Fig. 4 shows the results of these tests.
  • the spheroidal graphite cast irons of Examples 1 and 2 were both superior in the tensile strength and proof stress to the conventional spheroidal cast irons of References 1 and 2. Also it can be seen that the cast irons of Examples 1 and 2 were inferior in the elongation to the cast irons of References 1 and 2. However, the 10% and 12% elongation values indicate that either of the cast irons of Examples 1 and 2 is fully satisfactory as a material for turbine housing of automotive exhaust gas turbochargers, for example.
  • the spheroidal graphite cast irons of Examples 1 and 2 were higher in resistance to oxidation than the conventional spheroidal graphite cast iron of Reference 2 over the entire range of high temperatures in this test. At 750°C the cast irons of Examples 1 and 2 were even comparable in oxidation resistance to the high nickel spheroidal graphite cast iron of Reference 1.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
EP19820305306 1981-10-05 1982-10-05 Heat-resistant spheroidal graphite cast iron Expired EP0076701B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP157542/81 1981-10-05
JP15754281A JPS6053736B2 (ja) 1981-10-05 1981-10-05 耐熱用球状黒鉛鋳鉄

Publications (3)

Publication Number Publication Date
EP0076701A2 EP0076701A2 (en) 1983-04-13
EP0076701A3 EP0076701A3 (en) 1983-10-26
EP0076701B1 true EP0076701B1 (en) 1986-05-14

Family

ID=15651949

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19820305306 Expired EP0076701B1 (en) 1981-10-05 1982-10-05 Heat-resistant spheroidal graphite cast iron

Country Status (3)

Country Link
EP (1) EP0076701B1 (ja)
JP (1) JPS6053736B2 (ja)
DE (1) DE3271179D1 (ja)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1865082A1 (de) 2006-06-08 2007-12-12 Georg Fischer Eisenguss GmbH Gusseisenlegierung mit guter Oxydationbeständigkeit bei hoher Temperaturen
AU2006210102B2 (en) * 2005-02-01 2010-10-28 Danieli Corus Bv Support assembly for supporting heat regeneration checker work in a hot blast stove, hot blast stove provided with said support assembly, method of producing hot air using said hot blast stove

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6070162A (ja) * 1983-09-27 1985-04-20 Ishikawajima Harima Heavy Ind Co Ltd 耐熱性球状黒鉛フエライト鋳鉄
AUPO978297A0 (en) * 1997-10-14 1997-11-06 Camcast Industries Pty Ltd Iron alloy
KR20030028909A (ko) * 2001-10-04 2003-04-11 현대자동차주식회사 자동차 엔진 배기계용 주철 조성물
DE10233732A1 (de) * 2002-07-24 2004-02-05 Georg Fischer Fahrzeugtechnik Ag Gusseisenlegierung
WO2008112720A1 (en) * 2007-03-12 2008-09-18 Wescast Industries, Inc. Ferritic high-silicon cast irons
US7796706B2 (en) 2007-03-15 2010-09-14 Nokia Corporation Digital broadcast service discovery correlation
JP5232620B2 (ja) * 2008-12-18 2013-07-10 三菱重工業株式会社 球状黒鉛鋳鉄
US20100322813A1 (en) * 2009-06-23 2010-12-23 General Electric Company SiMo DUCTILE IRON CASTINGS IN GAS TURBINE APPLICATIONS
US8979488B2 (en) * 2011-03-23 2015-03-17 General Electric Company Cast turbine casing and nozzle diaphragm preforms
SE1250101A1 (sv) * 2011-04-01 2012-10-02 Scania Cv Ab Gjutjärnslegering samt därav tillverkad avgasledande komponent
CN102796940B (zh) * 2012-08-31 2014-05-07 丹阳市锦雄机械制造有限公司 一种高硅耐热球铁制备方法
JP6090905B2 (ja) * 2012-11-26 2017-03-08 株式会社日本製鋼所 高温延性と高温クリープ破断寿命に優れた球状黒鉛鋳鉄およびその製造方法
CN103509992A (zh) * 2013-10-15 2014-01-15 沈阳工业大学 一种耐热球墨铸铁研究及制备
CN110438281B (zh) * 2019-08-16 2021-04-16 哈尔滨理工大学 一种不含Si的稀土镁合金球化剂及其制备方法与应用
US11667995B2 (en) 2021-09-21 2023-06-06 Ford Global Technologies, Llc Cast iron alloy for automotive engine applications with superior high temperature oxidation properties

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR953445A (fr) * 1946-07-22 1949-12-06 British Cast Iron Res Ass Procédé de fabrication d'une fonte perfectionnée et produit en résultant
FR1024517A (fr) * 1949-09-17 1953-04-02 Mond Nickel Co Ltd Perfectionnements aux fontes grises
FR1056979A (fr) * 1952-02-22 1954-03-04 British Cast Iron Res Ass Production de la fonte grise
US2762705A (en) * 1953-01-23 1956-09-11 Int Nickel Co Addition agent and process for producing magnesium-containing cast iron
DE2428822A1 (de) * 1974-06-14 1976-01-02 Goetzewerke Sphaerogusseisenlegierung mit erhoehter verschleissbestaendigkeit

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2006210102B2 (en) * 2005-02-01 2010-10-28 Danieli Corus Bv Support assembly for supporting heat regeneration checker work in a hot blast stove, hot blast stove provided with said support assembly, method of producing hot air using said hot blast stove
EP1865082A1 (de) 2006-06-08 2007-12-12 Georg Fischer Eisenguss GmbH Gusseisenlegierung mit guter Oxydationbeständigkeit bei hoher Temperaturen

Also Published As

Publication number Publication date
JPS6053736B2 (ja) 1985-11-27
EP0076701A2 (en) 1983-04-13
DE3271179D1 (en) 1986-06-19
EP0076701A3 (en) 1983-10-26
JPS5858248A (ja) 1983-04-06

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