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US3615879A - Centrifugal mold for the casting of liquid metal and the process for producing said centrifugal mold - Google Patents

Centrifugal mold for the casting of liquid metal and the process for producing said centrifugal mold Download PDF

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Publication number
US3615879A
US3615879A US749411A US3615879DA US3615879A US 3615879 A US3615879 A US 3615879A US 749411 A US749411 A US 749411A US 3615879D A US3615879D A US 3615879DA US 3615879 A US3615879 A US 3615879A
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Prior art keywords
percent
steel
mold
carbon
manganese
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Expired - Lifetime
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US749411A
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English (en)
Inventor
Eugene Herzog
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Pont a Mousson SA
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Pont a Mousson SA
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D13/00—Centrifugal casting; Casting by using centrifugal force
    • B22D13/10—Accessories for centrifugal casting apparatus, e.g. moulds, linings therefor, means for feeding molten metal, cleansing moulds, removing castings
    • B22D13/101—Moulds
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten

Definitions

  • the present invention relates to molds for the casting of liquid metal, and in particular to molds for the centrifugal casting of iron pipes or other parts of revolution of metals or metal alloys having a melting point lower than l,300 C.
  • the shells have the outer face cooled by a spraying of water, whereas the inner face, which is exposed to the liquid metal, is brought to a temperature of about 650 C., with a maximum of 700 C. It has been observed that under these conditions and with steels of known type the inner wall of the mold undergoes variations in structure in the course of the thermic cycles imposed by the casting.
  • liquid metal casting molds are not only subjected to severe conditions of utilization but their manufacture poses many problems. Indeed, in order to be of utility, such molds must have a maximum permissible flexion of no more than 0.5 mm. In respect of hollow cylinders up to 7 meters long, 1.5 meter in diameter and having a thickness of up to I mm., this high precision can only be obtained after straightening and machining operations requiring many precautions. Further, the above-mentioned flexion must not be exceeded in the course of successive thermic cycles imposed on the molds during their utilization.
  • the desired steels must not be brittle when cold;
  • these steels must conserve a high hardness in the hot state (usually a Brinell hardness of 250-300 is required thereof);
  • steels are sought in which the spreading of the cracks is as slow as possible and this means selecting steels having high toughness;
  • the steel is water quenched or oil quenched and tempered at for instance 600-630C.
  • weldable low alloy steels employed in the production of sheet metal and in building has produced a range of water-hardenable and temperable steels whose compositions are often near those of the steels shown in Table I.
  • the steel Tl manufactured by the US. STEEL CORPORATION and having the composition: C 0.10-0.18 percent, Mn 0.5-1.0 percent, Ni 0.5 percent, M0 0.5 percent, Cr 1 percent with traces of B and V.
  • these steels which have a low alloy content and are weldable, are ductile, their Brinell hardness of 200-270 is insufficient. Air hardened, they have a Brinell hardness of 180-250 in respect of thicknesses of less than 25 mm. which is even lower than in the case of water hardening. Consequently these steels are unsuitable for the purpose in mind.
  • the object of the invention is to provide an improved mold for casting liquid metal, said mold being of a low alloy steel selected from the range of air-hardenable steels having 0.08-0.28 percent of carbon with additions not exceeding 5 percent of the total, this steel having throughout the thickness of the mold a regular and uniform structure in which at least 60 percent of the carbon is fixed in the form of special carbides, such as those of molybdenum, vanadium and tungsten, the remainder of the carbon being combined in the form of chromiumand manganese-saturated cementite.
  • a low alloy steel selected from the range of air-hardenable steels having 0.08-0.28 percent of carbon with additions not exceeding 5 percent of the total, this steel having throughout the thickness of the mold a regular and uniform structure in which at least 60 percent of the carbon is fixed in the form of special carbides, such as those of molybdenum, vanadium and tungsten, the remainder of the carbon being combined in the form of chromiumand manganese-saturated cementite.
  • the fineness of the carbides is less than 5 microns and their distance is for instance 20-25 microns.
  • Another object of the invention is to provide a process for producing the aforementioned improved mold. This process, starting with a low carbon steel, having a composition selected from the following limits by weight in addition to the iron:
  • FIG. 1 is a view, with the invention
  • FIGS. 2 and 3 are micrograph views of this mold after air quenching and tempering
  • FIG. 4 is a perspective view of a test specimen
  • FIG. 5 is a diagram of tests carried out on the test specimen shown in FIG. 4;
  • FIG. 6 is another diagram showing the comparative readings of the residual internal stresses in molds of currently used steel and of steel according to the invention and FIGS. 7 and 8 are micrograph views after oil hardening and tempering.
  • FIG. 1 shows diagrammatically and only by way of example, a mold A for the centrifugal casting of iron pipes having a male and a socket end.
  • the mold A is preferably formed by a centrifugal casting thereof since this casting results in a fairly rapid solidification and consequently a uniform distribution of the components.
  • This manner of producing the mold is preferred to that of casting from a large ever, this latter manner of proceeding is of utility in particular for large molds.
  • the shell is preferably air quenched between 950 and 900 C. and then tempered at around 640 C.
  • the Brinell hardness is then between 270 and 300.
  • FIGS. 2 and 3 show the structure S of the steel thus treated at a magnification of 500 and 6,600 respectively.
  • the carbides have a very regular distribution and a uniform fineness; their thickness is less than 5 microns with a distance therebetween of 20-25 microns. This uniform structure imparts to the materials great regularity in the flux of heat from the interior towards the exterior of the mold.
  • Test specimens such as that shown in FIG. 4 are formed from a portion of a cylinder 1 through which a conduit 2 exingot followed by forging and boring, howtends in the vicinity of the center corner or edge 3. These test specimens are placed in an induction furnace, the heating of which is concentrated on the edge 3. A circulation of water through the tube or conduit 2 cools the interior of the test specimen. To reproduce the conditions of utilization of a centrifugal casting mold, the specimens are subjected on their edge 3 to thermic cycles including a heating period of about two seconds which raises the surface temperature of the specimen to 650 C. and then a cooling period of about l0 sgconds so as to lower the surface temperature to about C. These thermic cycles or these successive violent heating and energetic cooling produce cracks on the edge 3.
  • the diagram shown in FIG. 5 gives, as a function of the number n of cycles to which the specimens are subjected, the lengths L of the cracks observed in hundredths of a millimeter.
  • the result is shown by the full line I, whereas the curve II in dotted line gives the comparative result for a steel of a known AFNOR type I8CDV4.
  • the specimens corresponding to the steel of the molds according to the invention have cracks on an average only half the length of those of the specimens of the known steel.
  • the residual internal stresses of the centrifugal casting mold having an inside diameter of I I2 mm. and a thickness of 12 mm. are measured.
  • the diagram shown in FIG. 6 gives the mean result of these readings.
  • the distance x in millimeters measured from the inner face s (FIG. I) of the mold A are plotted as abscissae and the stresses, measured in decanewtons per square millimeter, are plotted as ordinates y.
  • the positive values in ordinates represent the residual tensile stresses and the negative values the compression stresses.
  • curve III in full line represents the behavior of the molds of steel according to the invention
  • curve IV in dotted line represents the behavior of the molds of steel of the known type l8CDV4).
  • residual tensile stresses exist of the order of 3OdaNlmm. for the mold according to the invention, and SOdaN/mm. for a mold of the known steel.
  • the residual internal stress measured on the inner wall of the mold according to the invention therefore does not reach half that measured on a mold of steel of the known type l8CDV4).
  • FIGS. 7 and 8 which are similar to FIGS. 2 and 3, show, in the case of oil quenching, the micrographs of the structures 8 obtained. There can be distinguished against a background of even ferrite a lamellae b of carbides which are shorter, finer and more uniformly distributed than in the case of air quenching (compare FIGS. 7 and 8 with FIGS. 2 and 3).
  • traces of boron (0.0020.004 percent) and traces of aluminum (0.0500.150 percent) can be added, the aluminum protecting the boron from oxidation and nitriding.
  • Nickel can also be added (0.50-1.50 percent) for increasing the depth of the hardening.
  • Coalescence of the carbides cycles must be slow, whence ing point carbides. For this (0.30-0.50 percent), 0.02-0.05 percent) can under the action of the heating the interest of having high meltpurpose, additions of niobium titanium and zirconium (totalizing be employed for fixing, in addition the carbon which passes from the dissolved state between 1,000-1 ,200E- C. to the precipitated carbide state at around 650-700C. inasmuch as the other requirements of sufficient ductility for a Vickers hardness of 300 are respected.
  • a steel having the following composition by weight, in addition to the iron could be employed in particular:
  • the molds according to the invention are suitable not only for casting liquid iron but also for casting any metal such as aluminum, copper or copper alloys having a melting point under 1,300 C.
  • a centrifugal casting mold for casting liquid metal said mold being of a low alloy air-hardenable steel consisting essentially of:
  • a centrifugal casting mold as claimed in claim I said steel containing 002-0115 percentgf titanium and zirconium.
  • a processfor producing a inold for casting liquid metal said steel having throughout the thickness of the mold a regular and uniform structure in which 60-90 percent of the carbon is fixed in the form of carbides, the remainder of the carbon being combined in the form of chromiumand manganese-saturated cementite, the fineness of the carbides being less than 5 microns and the distance therebetween being about 20-25 microns, said process comprising starting with a low carbon steel having a composition consisting essentially of by weight Carbon 0.08-0.28% Manganese 0.60-l .40% Silicon 0.20-0.70lv Chromium 0.90-l .50% Molybdenum 0.20- l .00% Tungsten 0.10-2.00! Vanadium[0.00-0.l0%] s 0.10% Iron balance.
  • a process as claimed in claim 5, comprising adding 0.50-1.50 percent by weight of nickel to the said low carbon steel composition.
  • a process as claimed in claim 5, comprising adding a trace to the said low carbon steel adding a trace, 0002-0004 percent, of boron and a trace 0.050-0.l50 percent, of aluminum to the said low carbon steel composition.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
  • Heat Treatment Of Steel (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
US749411A 1967-08-08 1968-08-01 Centrifugal mold for the casting of liquid metal and the process for producing said centrifugal mold Expired - Lifetime US3615879A (en)

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FR117222 1967-08-08

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BE (1) BE718520A (nl)
FR (1) FR1551909A (nl)
GB (1) GB1228179A (nl)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3751307A (en) * 1972-04-26 1973-08-07 Us Army Thermal-mechanically processed low-alloy steel
US3791818A (en) * 1972-08-14 1974-02-12 Us Air Force Steel alloy
US4030944A (en) * 1976-04-15 1977-06-21 Ceskoslovenska Akademie Ved Production of annular products from centrifugally cast steel structures
US4129002A (en) * 1974-11-20 1978-12-12 Van Kooten B.V. Cylinder piece for a pile driving ram
US5714116A (en) * 1995-04-27 1998-02-03 Creusot Loire Industrie (Societe Anonyme) Steel and process for the manufacture of components having high abrasion resistance
WO2003083153A1 (fr) * 2002-04-03 2003-10-09 Industeel France Bloc en acier pour la fabrication de moules d'injection de matiere plastique ou pour la fabrication de pieces pour le travail des metaux
FR2858331A1 (fr) * 2003-08-01 2005-02-04 Aubert Et Duval Surface en contact avec le titane ou un alliage de titane
US6902631B2 (en) 1999-11-02 2005-06-07 Ovako Steel Ab Air-hardening, low to medium carbon steel for improved heat treatment

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2428782A1 (fr) * 1978-06-13 1980-01-11 Pont A Mousson Elements tubulaires en acier pour conduites en mer
EP0411515B1 (en) * 1989-07-31 1993-09-08 Mitsubishi Jukogyo Kabushiki Kaisha High strength heat-resistant low alloy steels

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3751307A (en) * 1972-04-26 1973-08-07 Us Army Thermal-mechanically processed low-alloy steel
US3791818A (en) * 1972-08-14 1974-02-12 Us Air Force Steel alloy
US4129002A (en) * 1974-11-20 1978-12-12 Van Kooten B.V. Cylinder piece for a pile driving ram
US4030944A (en) * 1976-04-15 1977-06-21 Ceskoslovenska Akademie Ved Production of annular products from centrifugally cast steel structures
US5714116A (en) * 1995-04-27 1998-02-03 Creusot Loire Industrie (Societe Anonyme) Steel and process for the manufacture of components having high abrasion resistance
AU692377B2 (en) * 1995-04-27 1998-06-04 Industeel Creusot Steel and process for the manufacture of components having high abrasion resistance
US6902631B2 (en) 1999-11-02 2005-06-07 Ovako Steel Ab Air-hardening, low to medium carbon steel for improved heat treatment
WO2003083153A1 (fr) * 2002-04-03 2003-10-09 Industeel France Bloc en acier pour la fabrication de moules d'injection de matiere plastique ou pour la fabrication de pieces pour le travail des metaux
US20050115644A1 (en) * 2002-04-03 2005-06-02 Jean Beguinot Bulk steel for the production of injection moulds for plastic material or for the production of pieces for working metals
FR2838138A1 (fr) * 2002-04-03 2003-10-10 Usinor Acier pour la fabrication de moules d'injection de matiere plastique ou pour la fabrication de pieces pour le travail des metaux
CN1317416C (zh) * 2002-04-03 2007-05-23 法国安达斯戴乐公司 用于制造塑性材料注塑成型用的模具或用于制造金属加工部件的钢锭
AU2003258841B2 (en) * 2002-04-03 2008-05-29 Industeel France Bulk steel for the production of injection moulds for plastic material or for the production of pieces for working metals
FR2858331A1 (fr) * 2003-08-01 2005-02-04 Aubert Et Duval Surface en contact avec le titane ou un alliage de titane
WO2005012586A1 (fr) * 2003-08-01 2005-02-10 Aubert & Duval Surface en contact avec le titane ou un alliage de titane
US20050161124A1 (en) * 2003-08-01 2005-07-28 Gerard Raisson Titanium or titanium alloy contacting surface

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Publication number Publication date
BE718520A (nl) 1968-12-31
FR1551909A (nl) 1969-01-03
GB1228179A (nl) 1971-04-15

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