US3764298A - Method of melting cast iron - Google Patents

Method of melting cast iron Download PDF

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Publication number
US3764298A
US3764298A US00854606A US3764298DA US3764298A US 3764298 A US3764298 A US 3764298A US 00854606 A US00854606 A US 00854606A US 3764298D A US3764298D A US 3764298DA US 3764298 A US3764298 A US 3764298A
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United States
Prior art keywords
cast iron
bath
graphite
superheating
silicon carbide
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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 - Lifetime
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US00854606A
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English (en)
Inventor
W Moore
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MEEHANITE WORLDWIDE Corp
Meehanite Metal Corp
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Meehanite Metal Corp
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Assigned to MEEHANITE WORLDWIDE CORPORATION reassignment MEEHANITE WORLDWIDE CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: MEEHANITE METAL CORPORATION, A MO. CORP.
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/08—Manufacture of cast-iron
    • 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
    • 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

Definitions

  • My invention is based on the discovery that small portions of silicon carbide may be added to the bath and will completely prevent the deleterious effects of high superheating temperatures.
  • An object of this invention is to provide a means whereby cast iron may be heated to a high pouring temperature, without ill effect.
  • a further object is to allow the production of cast iron of normal graphite structure at high superheat temperatures.
  • a further object is to improve the fluidity of a cast iron melt.
  • a further object is to provide an improved melt for nodular cast iron.
  • a further object is to decrease the degree of temperature control necessary in the melting of cast iron.
  • FIG. 1 is the structure at 100 diameters of a cast iron heated to 2600 F characterized by normal random graphite and areas of undercooled graphite;
  • FIG. 2 is the structure at 100 diameters of the same cast iron heated to a temperature of 2800 F., characterized by undercooled graphite type D and, also, type E of the interdendritic variety;
  • FIG. 3 is the structure at 100 diameters of a cast iron which has been heated to 2900" F., after adding onequarter percent silicon carbide. Characterized by normal flake graphite and some undercooled graphite, but no type B, interdendritic undercooled graphite;
  • FIG. 4 is the structure at 100 diameters of a cast iron which has been heated to 3000 F. after adding onequarter percent silicon carbide, characterized by normal flake graphite and a very slight tendency to interdendritic graphite;
  • FIG. 5 is the chill wedges test on a cast iron heated to from 2600 F. in increments of 100 F. to 3000 F.
  • FIG. 6 is the chill wedge test on a cast iron heated after adding one-quarter percent silicon carbide from 2600 F. in increments of F. to 3000 F., showing practically constant chill at all temperatures of superheat.
  • undercooled graphite In connection with the undercooled graphite, it appears that undercooled graphite is quite normal in an electric furnace melt, but that the interdendritic or type E graphite, which only seems to occur at or above a temperature of 2750 F., is more harmful as it does not respond completely to subsequent nucleation, which is a common practice to those skilled in the art.
  • nodular cast iron In the manufacture of nodular cast iron, it has also been found that a low chill value in the initial bath is extremely desirable. Such a low chill value gives an increased nodule count with better mechanical properties and allows, also, the production of a good nodular graphite cast iron, with normal additions of nodularizing agents such as magnesium and cerium.
  • cerium is used as a nodularizing agent
  • a high chill bath will produce extremely stable carbides on the addition of cerium and these carbides call for excessively long annealing temperatures in the final castings made from such a bath.
  • cast iron baths made in electric furnaces whether they be used for castings containing flake graphite or for castings containing nodular graphite, must be produced with a relatively low chill value for the particular composition of the bath. Allowing the development of higher chill values than those expected from a given composition will lead to inferior metal for the reasons given above.
  • FIG. 6 in the specification shows the chill value of a bath of Class 40 cast iron to which one-quarter percent of silicon carbide, in granulated form, was added immediately after melting, but before superheating. Superheating this bath to temperatures as high as 3000 F. did not increase the chill value over what it was at superheating temperatures as low as 2600" F.
  • FIG. shows the chill value of the same cast iron but to which no addition was made prior to superheating.
  • FIGS. 1 and 2 illustrate the structure of a typical Class 40 iron, which was heated to 2600 F. in FIG. 1 and to 2800 F. in FIG. 2. Portions of the bath were cast into test bars, which were subsequently examined for microstructure.
  • the structure In the casting of the 2600 F. superheating, illustrated in FIG. 1, the structure consisted of normal random flake graphite, together with some undercooled graphite, which would be typical of such an iron cast in the uninoculated condition from such a superheating temperature.
  • FIG. 2 illustrates the same iron Which has been superheated to a higher temperature, namely, 2800 F.
  • the structure taken from a representative test bar contains a fairly high proportion of interdendritic graphite, along with normal undercooled graphite.
  • the appearance of interdendritic graphite is typical in cast iron melts heated to temperatures in the vicinity of 2800 F.
  • FIGS. 3 and 4 represent a similar Class 40" cast iron superheated to temperatures of 2900 F. and 3000 F. respectively.
  • an addition of one-quarter percent of granulated silicon carbide was made to the bath immediately after meltdown. Portions of the bath, taken and poured into representative test bars showed that the structure in the case shown in FIG. 3, where the heating temperature was 2900 F., consisted of normal random flake graphite, along with undercooled graphite. At a superheating temperature of 3000- F., shown in FIG. 4, the structure consisted of normal random flake graphite, with only very light traces of interdendritic undercooled graphite.
  • silicon carbide is elfective in preventing the formation of interdendritic graphite, even at superheating temperatures as high as 3000 F. Where silicon carbide is not present, these undesirable structures may occur at temperatures as low as 2800 F.
  • the amount of silicon carbide necessary to perform the process of my invention may be as little as one-eighth percent by weight of the bath or it can be as high as two percent, or more, by Weight of the bath.
  • a method of melting cast iron in an electric furnace at high temperatures consisting essentially of the steps of melting a cast iron charge in the presence of a small but effective amount of silicon carbide and superheating the melt to any desired temperature between about 2750 F. and 3000 -F. whereby said silicon carbide acts to prevent an increase in the chill value of the bath during superheating and to decrease the amount of undercooled graphite in the structure of the cast iron cast from said melt.
  • said small but etfective amount of silicon carbide is in the range of from A; of one percent to two percent based on the weight of iron.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Sealing Devices (AREA)
  • Diaphragms And Bellows (AREA)
US00854606A 1969-09-02 1969-09-02 Method of melting cast iron Expired - Lifetime US3764298A (en)

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US85460669A 1969-09-02 1969-09-02

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US3764298A true US3764298A (en) 1973-10-09

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US (1) US3764298A (xx)
AT (1) AT326710B (xx)
BE (1) BE748535A (xx)
CH (1) CH560249A5 (xx)
DE (1) DE2034806A1 (xx)
DK (1) DK137652B (xx)
ES (1) ES378057A1 (xx)
FI (1) FI49988C (xx)
FR (1) FR2060345B1 (xx)
GB (1) GB1299748A (xx)
NL (1) NL7013010A (xx)
NO (1) NO125353B (xx)
ZA (1) ZA705077B (xx)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2746478A1 (de) * 1977-10-15 1979-05-23 Maschf Augsburg Nuernberg Ag Verfahren zum legieren und/oder impfen und/oder desoxidieren von im kupolofen erzeugten gusseisenschmelzen
CN112589059A (zh) * 2020-11-26 2021-04-02 莱州鸿源台钳制造有限公司 一种向浇注包内添加微量碳化硅的铸造方法

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3975191A (en) * 1974-11-25 1976-08-17 Rote Franklin B Method of producing cast iron
DE2653341C2 (de) * 1976-11-24 1986-10-02 Caspers, Karl-Heinz, Ing.(grad.), 8500 Nürnberg Verfahren zum Legieren und/oder Desoxidieren von im Kupolofen erzeugten Gußeisenschmelzen mit lamellarem Graphit sowie Vorrichtung zur Durchführung des Verfahrens
DE3431263A1 (de) * 1984-08-24 1986-03-06 Elektroschmelzwerk Kempten GmbH, 8000 München Verfahren zur behandlung von gusseisenschmelzen mit siliciumcarbid
IT1282545B1 (it) * 1996-05-03 1998-03-27 Rinaldo Cattaneo Precondizionamento delle ghise fuse al forno elettrico per la produzione di getti di sicurezza

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB143596A (en) * 1919-02-19 1920-05-19 Guy James Stock Improvements in and relating to the manufacture of grey iron

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2746478A1 (de) * 1977-10-15 1979-05-23 Maschf Augsburg Nuernberg Ag Verfahren zum legieren und/oder impfen und/oder desoxidieren von im kupolofen erzeugten gusseisenschmelzen
CN112589059A (zh) * 2020-11-26 2021-04-02 莱州鸿源台钳制造有限公司 一种向浇注包内添加微量碳化硅的铸造方法

Also Published As

Publication number Publication date
FI49988C (fi) 1975-11-10
DK137652B (da) 1978-04-10
GB1299748A (en) 1972-12-13
BE748535A (fr) 1970-09-16
AT326710B (de) 1975-12-29
FR2060345B1 (xx) 1974-07-12
DK137652C (xx) 1978-09-25
ES378057A1 (es) 1972-12-01
DE2034806A1 (de) 1971-04-08
FI49988B (xx) 1975-07-31
NO125353B (xx) 1972-08-28
FR2060345A1 (xx) 1971-06-18
NL7013010A (xx) 1971-03-04
ATA722970A (de) 1975-03-15
ZA705077B (en) 1971-04-28
CH560249A5 (xx) 1975-03-27

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Legal Events

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AS Assignment

Owner name: MEEHANITE WORLDWIDE CORPORATION, SOUTH CAROLINA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MEEHANITE METAL CORPORATION, A MO. CORP.;REEL/FRAME:004651/0769

Effective date: 19861212

Owner name: MEEHANITE WORLDWIDE CORPORATION, 112 CAROLINA COVE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:MEEHANITE METAL CORPORATION, A MO. CORP.;REEL/FRAME:004651/0769

Effective date: 19861212