US2538239A - Method for hardening cast iron - Google Patents

Method for hardening cast iron Download PDF

Info

Publication number
US2538239A
US2538239A US775373A US77537347A US2538239A US 2538239 A US2538239 A US 2538239A US 775373 A US775373 A US 775373A US 77537347 A US77537347 A US 77537347A US 2538239 A US2538239 A US 2538239A
Authority
US
United States
Prior art keywords
casting
temperature
heating
castings
hardening
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US775373A
Inventor
George B Farnsworth
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.)
THOMAS E PIPER
Original Assignee
THOMAS E PIPER
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by THOMAS E PIPER filed Critical THOMAS E PIPER
Priority to US775373A priority Critical patent/US2538239A/en
Application granted granted Critical
Publication of US2538239A publication Critical patent/US2538239A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/20—Carburising
    • C23C8/22—Carburising of ferrous surfaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D5/00—Heat treatments of cast-iron

Definitions

  • the present invention relates to a method for hardening cast iron.
  • An object of the present invention is to harden cast iron.
  • Another object is to develop a new and simple process for hardening cast iron.
  • Another object is to make an improved hea treating process for cast iron.
  • any type of gray iron casting may be employed, and the casting may be hardened either in the malleable or ordinary; condition. Since a slight modification is required in the hardening of malleable castings, I first shall explain how the process is performed on-ordinary iron castings.
  • any machining is to be done on the castings, this is done before the hardening process is initiated, since once hardened, the castings are too hard for ordinary machining, except where finish grinding of some parts may be required. Such finish grinding can of course be done even on hardened work.
  • the initial heating which begins the present hardening process is understaken, the castings must never be permitted to cool below a temperature of approximately 450 vF. until the process is completed.
  • no preannealing should be attempted prior to the beginning of the hardening process, since such should be sufficiently slow so as not to exert expansion stresses on the castings, but to permit gradual and uniform expansion of all the parts.
  • the castings After soaking at the 1700 temperature for the required length of time, which opens the grain structure of the cast iron, the castings are allowed to cool to a temperature'between 450 F. and 700 F. This cooling must be permitted to occur slowly, either in a furnace, or if the furnace capacity is desired for other uses, the castings may be packed for example in air slaked lime.
  • annealing has a tendency to cause cracks in main a suitable liquid carburizer.
  • the carburizing may be performed in the same manner as with steel, for example, by packing in a suitable carburizing agent or by immersing Since these carburizing agents are well-known to the art, it is not necessary to specify them in detail.
  • the casting in its investment of carburizing material, is gradually broughtup to a temperature of 1700 F. and is maintained at the carburizing temperature for a time determined in each instance by the depth to which the carburizing is desired to penetrate. After the carburizing period has elapsed, the casting again is allowed to cool slowly to a temperature slightly above 450 F. The casting then is removed from the carburizer and the dust from the carburizing pack is removed with an air blast or brush.
  • the prom ess is generally similar to that described for the solid carburizing agent with one or two exceptions. These exceptions are as follows: After machining, and the first heating to 1700 F. and the gradual cooling to 450 F. to 700 F., and before immersing the casting in the carburizing bath, the casting first is slowly re-heated to a temperature between 1250 F. to 1400 F. It then is immersed in the liquid carburizing bath which is maintained at a temperature between 1650 F. and 1700 F. The casting is permitted to remain in the carburizr in the above-mentioned temperature range for a length of time depending upon the cross-section of the casting and the depth of penetration of carburization' desired.
  • the method of hardening a non-malleable gray iron casting which comprises heating the casting to atemperature of 1700F. at a rate slow enough to minimize expansion stresses due to heating, maintaining the casting at said temperature for a length of time sufficient to open proximating 400 F. to 500 F.
  • the method of hardening a non-malleable gray iron casting which comprises heating the casting to a temperature of approximately 1700 F. at a rate slow enough to minimize expansion stresses due to heating, maintaining the casting at said temperature for a length of timevarying with the thickness of the casting and being of the order of one hour for a casting having maximum thickness of two inches, cooling the casting slowly to a temperature between 450 F. and 700 F., heating the casting in a carburizing material to a temperature of approximately 1650 F.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)

Description

Patented Jan. 16, 1951 METHOD FOR HARDENIN G CAST IRON George B. Farnsworth, Ojai, Calif., assignor of one-fourth to Thomas E. Piper, Santa Monica,
Calif.
No Drawing. Application September 20, 1947, Serial No. 775,373
2 Claims.
The present invention relates to a method for hardening cast iron.
In the past many attempts have been made to harden cast iron but so far as applicant is aware no one has ever succeeded in hardening more than a very thin shell on an iron casting and such mold is, of course, well known, but since such chilled portions are very difiicult to machine, this practice has been limited to uses where a minimum of finish machining of the chill hardened portions was required.
An object of the present invention is to harden cast iron.
Another object is to develop a new and simple process for hardening cast iron.
Another object is to make an improved hea treating process for cast iron.
In practicing my invention, any type of gray iron casting may be employed, and the casting may be hardened either in the malleable or ordinary; condition. Since a slight modification is required in the hardening of malleable castings, I first shall explain how the process is performed on-ordinary iron castings.
First, if any machining is to be done on the castings, this is done before the hardening process is initiated, since once hardened, the castings are too hard for ordinary machining, except where finish grinding of some parts may be required. Such finish grinding can of course be done even on hardened work. Once the initial heating which begins the present hardening process is understaken, the castings must never be permitted to cool below a temperature of approximately 450 vF. until the process is completed. In the case of ordinary castings, no preannealing should be attempted prior to the beginning of the hardening process, since such should be sufficiently slow so as not to exert expansion stresses on the castings, but to permit gradual and uniform expansion of all the parts. In the case of castings .of extremely critical shapes, for example a pulley having large hub, heavy rim, and relatively thin spokes, unless the parts are brought up to temperature very gradually, fracture of the spokes is almost certain to occur. The castings are held at the 1700 F. temperature for a time, dependi ng on the size and sections of the castings involved. For example, a casting having an average maximum two-inch section would be held at this temperature for approximately one hour.
After soaking at the 1700 temperature for the required length of time, which opens the grain structure of the cast iron, the castings are allowed to cool to a temperature'between 450 F. and 700 F. This cooling must be permitted to occur slowly, either in a furnace, or if the furnace capacity is desired for other uses, the castings may be packed for example in air slaked lime.
When the parts thus have cooled gradually to the lower temperature which, as stated, must not be less than 450 F., the castings are carburized.
annealing has a tendency to cause cracks in main a suitable liquid carburizer.
The carburizing may be performed in the same manner as with steel, for example, by packing in a suitable carburizing agent or by immersing Since these carburizing agents are well-known to the art, it is not necessary to specify them in detail.
In the case where solid or granular carburizing material is employed, after the casting is packed in the manner usually employed for hardening steel, the casting in its investment of carburizing material, is gradually broughtup to a temperature of 1700 F. and is maintained at the carburizing temperature for a time determined in each instance by the depth to which the carburizing is desired to penetrate. After the carburizing period has elapsed, the casting again is allowed to cool slowly to a temperature slightly above 450 F. The casting then is removed from the carburizer and the dust from the carburizing pack is removed with an air blast or brush.
Still maintaining the casting at a temperature not below 450 F. it again is placed in the furnace and is reheated to a temperature of approximately 1450 to 1500 F. The higher of these two temperatures is better. The casting then is quenched in a good grade of quenching oil and then is drawn. The temperature of the draw is governed by the finished hardness desired. Usually a drawing temperature of 450 F. to 500 F. covers the range desired.
In using a liquid carburizing agent, the prom ess is generally similar to that described for the solid carburizing agent with one or two exceptions. These exceptions are as follows: After machining, and the first heating to 1700 F. and the gradual cooling to 450 F. to 700 F., and before immersing the casting in the carburizing bath, the casting first is slowly re-heated to a temperature between 1250 F. to 1400 F. It then is immersed in the liquid carburizing bath which is maintained at a temperature between 1650 F. and 1700 F. The casting is permitted to remain in the carburizr in the above-mentioned temperature range for a length of time depending upon the cross-section of the casting and the depth of penetration of carburization' desired. Usually a period of about two hours will sufiice for ordinary depth of cast. After the carburizing is completed the casting is quenched in liq-' uid salts at a temperature of 425 F. and then is allowed. to cool in the open air.
No drawing is required in the case of castings quenched in the liquid salt bath, but it should be borne in mind that the casting must be permitted to cool from the temperature of the quench to room temperature before attempting to wash off the coating of salt which solidifies and adheres to the casting when it is withdrawn from the salt bath. Otherwise the castings are very the grain structure in the casting, such time be ing longer for castings of greater mass and being of the order of one hour for a casting having maximum thickness of two inches, cooling the casting slowly to a temperature between 450 F. and 700 E, heating the casting; while at least partially enclosed in a carburizing material to a temperature of 1700 F., maintaining said cast ing while so enclosed at said latter temperature for a length of time determined by the depth to which it is desired to harden the casting, slowly cooling the casting to a temperature slightly over 450 F., removing, the casting from the carburizer, heating the casting to a temperature between 1450,F. and1500 F., quenching the casting in oil, and drawing the casting at temperature apapt to fracture if not permitted to cool gradually from the salt quenching bath temperature to room temperature.
In hardening malleable castings after the malleablizing process has been completed, the castings are'machined. After machining the hardening process is carried out the same as with ordinary castings, except that in all cases where temperatures above 1600 F. are specified, these temperatures must be limited to 1600 F. maximum. Any temperature above 1600 F. will deinvention. It is; desired, therefore, not to limit theinvention except as set forth in the following claims.
Iclaim:
1. The method of hardening a non-malleable gray iron casting which comprises heating the casting to atemperature of 1700F. at a rate slow enough to minimize expansion stresses due to heating, maintaining the casting at said temperature for a length of time sufficient to open proximating 400 F. to 500 F.
2. The method of hardening a non-malleable gray iron casting which comprises heating the casting to a temperature of approximately 1700 F. at a rate slow enough to minimize expansion stresses due to heating, maintaining the casting at said temperature for a length of timevarying with the thickness of the casting and being of the order of one hour for a casting having maximum thickness of two inches, cooling the casting slowly to a temperature between 450 F. and 700 F., heating the casting in a carburizing material to a temperature of approximately 1650 F. to 1700 F., maintaining said casting in said carburizer at said latter temperature range for a length of time determined by the depth to which it is desired to harden the casting, slowly cooling the casting to atemperature slightly over 450 F., removing the casting from the carburizer, heating the casting to a temperature between 1450 F. and 1500 F., and quenching the castmg.
GEORGE E. FARNSWORTH.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES, PATENTS Number Name Date 1,688,438 Schwartz Oct. 23, 1928 1,760,239 Lauenstein et al. May 27, 1930 1,894,752 Bozard et al Jan. 17, 1933 1,934,313 Lauenstein Nov. 7, 1933 1,980,578 Ford Nov. 13, 1934 2,008,452 Jewett et a1 July 16, 1935 FOREIGN PATENTS Number Country Date 418,873 Great Britain Nov. 1, 1934 OTHER REFERENCES Metals and Alloys, September 1931, page 131.

Claims (1)

1. THE METHOD OF HARDENING A NON-MALLEABLE GRAY IRON CASTING WHICH COMPRISES HEATING THE CASTING TO A TEMPERATURE OF 1700* F. AT A RATE SLOW ENOUGH TO MINIMIZE EXPANSION STRESSES DUE TO HEATING, MAINTAINING THE CASTING AT SAID TEMPERATURE FOR A LENGTH OF TIME SUFFICIENT TO OPEN THE GRAIN STRUCTURE IN THE CASTING, SUCH TIME BEING LONGER FOR CASTING OF GREATER MASS AND BEING OF THE ORDER OF ONE HOUR FOR A CASTING HAVING MAXIMUM THICKNESS OF TWO INCHES, COOLING THE CASTING SLOWLY TO A TEMPERATURE BETWEEN 450* F. AND 700* F., HEATING THE CASTING WHILE AT LEAST PARTIALLY ENCLOSED IN A CARBURIZING MATERIAL TO A TEMPERATURE OF 1700* F., MAINTAINING SAID CASTING WHILE SO ENCLOSED AT SAID LATTER TEMPERATURE FOR A LENGTH OF TIME DETERMINED BY THE DEPTH TO WHICH IT IS DESIRED TO HARDEN THE CASTING, SLOWLY COOLING THE CASTING TO A TEMPERATURE SLIGHTLY OVER 450* F., REMOVING THE CASTING FROM THE CARBURIZER, HEATING THE CASTING TO A TEMPERATURE BETWEEN 1450* F. AND 1500* F., QUENCHING THE CASTING IN OIL, AND DRAWING THE CASTING AT TEMPERATURE APPROXIMATING 400* F. TO 500* F.
US775373A 1947-09-20 1947-09-20 Method for hardening cast iron Expired - Lifetime US2538239A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US775373A US2538239A (en) 1947-09-20 1947-09-20 Method for hardening cast iron

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US775373A US2538239A (en) 1947-09-20 1947-09-20 Method for hardening cast iron

Publications (1)

Publication Number Publication Date
US2538239A true US2538239A (en) 1951-01-16

Family

ID=25104195

Family Applications (1)

Application Number Title Priority Date Filing Date
US775373A Expired - Lifetime US2538239A (en) 1947-09-20 1947-09-20 Method for hardening cast iron

Country Status (1)

Country Link
US (1) US2538239A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3751243A (en) * 1971-01-08 1973-08-07 Alcan Res & Dev Procedure for quenching dross
US20050063852A1 (en) * 2001-12-12 2005-03-24 Takeshi Hida Screw compressor and method of manufacturing rotor for the same

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1688438A (en) * 1926-12-23 1928-10-23 Nat Malleable & Steel Castings Making malleable-iron castings
US1760239A (en) * 1926-12-29 1930-05-27 Link Belt Co Process of treating malleableized cast iron
US1894752A (en) * 1929-01-21 1933-01-17 James L Summers Method of treating gray cast-iron and malleable iron
US1934313A (en) * 1932-01-23 1933-11-07 Link Belt Co Method of heat treating malleableized cast iron
GB418873A (en) * 1933-11-30 1934-11-01 Walter Cotterill Improvements in the manufacture and production of malleable iron
US1980578A (en) * 1922-02-10 1934-11-13 John H Bruninga Art of treating cast iron castings
US2008452A (en) * 1931-09-23 1935-07-16 Chain Belt Co Heat treated cast iron and process of producing the same

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1980578A (en) * 1922-02-10 1934-11-13 John H Bruninga Art of treating cast iron castings
US1688438A (en) * 1926-12-23 1928-10-23 Nat Malleable & Steel Castings Making malleable-iron castings
US1760239A (en) * 1926-12-29 1930-05-27 Link Belt Co Process of treating malleableized cast iron
US1894752A (en) * 1929-01-21 1933-01-17 James L Summers Method of treating gray cast-iron and malleable iron
US2008452A (en) * 1931-09-23 1935-07-16 Chain Belt Co Heat treated cast iron and process of producing the same
US1934313A (en) * 1932-01-23 1933-11-07 Link Belt Co Method of heat treating malleableized cast iron
GB418873A (en) * 1933-11-30 1934-11-01 Walter Cotterill Improvements in the manufacture and production of malleable iron

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3751243A (en) * 1971-01-08 1973-08-07 Alcan Res & Dev Procedure for quenching dross
US20050063852A1 (en) * 2001-12-12 2005-03-24 Takeshi Hida Screw compressor and method of manufacturing rotor for the same
US6884049B2 (en) * 2001-12-12 2005-04-26 Hitachi, Ltd., Screw compressor and method of manufacturing rotor for the same

Similar Documents

Publication Publication Date Title
US3076361A (en) Rolling steel in ferritic state
US3117041A (en) Heat treated steel article
US3784416A (en) Manufacture of white cast iron
US2538239A (en) Method for hardening cast iron
US3216869A (en) Method of heat treating steel
US2818359A (en) Method of making flanged cylinder liners
US4070210A (en) Method for hot and immersion alumising of compactly formed ferrous alloy products
US2875109A (en) Method for the isothermal treatment of alloys after casting
US2887421A (en) Method of producing castings having high mechanical properties
US2899346A (en) Cast iron heat
US2087766A (en) Method of making rolled products
US1871544A (en) Cast iron article and method of manufacturing thereof
US1399044A (en) Heat treatment of metals
US2895860A (en) Pressure chill-castings of iron
US3732127A (en) Method of heat processing alloy steel to obtain maximum softness and uniformity
US2798018A (en) Method of removing gaseous segregation from metals
US2087768A (en) Ferrous metal and method of making same
JPH0512411B2 (en)
US2426773A (en) Tempering process for steel objects
US2906651A (en) Method for producing malleabilized castings
US3711342A (en) Method of heat treating steel strip
US2906653A (en) Die-casting of iron in chill-moulds
US2493339A (en) Heat-treatment of cast iron
US2760924A (en) Method of polishing stamped steel articles
US3141801A (en) Method of hardening a case hardened steel