EP0105368B1 - Verfahren zur warmverformung von metallen, die beim walzen rissanfällig sind - Google Patents

Verfahren zur warmverformung von metallen, die beim walzen rissanfällig sind Download PDF

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Publication number
EP0105368B1
EP0105368B1 EP83902518A EP83902518A EP0105368B1 EP 0105368 B1 EP0105368 B1 EP 0105368B1 EP 83902518 A EP83902518 A EP 83902518A EP 83902518 A EP83902518 A EP 83902518A EP 0105368 B1 EP0105368 B1 EP 0105368B1
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EP
European Patent Office
Prior art keywords
metal
bar
steel alloy
hot
cross
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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
EP83902518A
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English (en)
French (fr)
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EP0105368A4 (de
EP0105368A1 (de
Inventor
Henry E. Chia
Ronald D. Adams
Niles N. Engel
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Southwire Co LLC
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Southwire Co LLC
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Publication date
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/1206—Accessories for subsequent treating or working cast stock in situ for plastic shaping of strands
    • 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
    • C21D7/00—Modifying the physical properties of iron or steel by deformation
    • C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
    • B21B3/003—Rolling non-ferrous metals immediately subsequent to continuous casting, i.e. in-line rolling

Definitions

  • the present invention relates to the hot forming of metals, and more particularly relates to the continuous casting and hot forming of the as-cast bars of certain impure or alloyed steels which may be prone to crack during hot-rolling.
  • metals such as copper and aluminum
  • metals may be continuously cast, either in stationary vertical molds or in a rotating casting wheel, to obtain a cast bar which is then immediately hot formed, while in a substantially as-cast condition, by passing the cast bar exiting the mold to and through the roll stands of a rolling mill while the cast bar is still at a hot-forming temperature.
  • the as-cast structure of the metal bar is such that cracking of the cast bar during hot forming may be a problem if the cast bar is required to be directly hot formed into a semi-finished product, such as redraw rod, during which the initially large cross-sectional area of the cast bar is substantially reduced by a plurality of deformations along different axes to provide a much smaller cross-sectional area in the product.
  • DE-A-2019700 describes a method of making thick metal sheet from continuously cast strand, in which the strand, immediately after casting, is subjected to compression whereby its cross section is reduced by seven to twenty percent, to allow the production of thick sheet of good quality.
  • GB-A-2014071 describes a method of continuously casting steel in which, for improving the internal quality and decreasing non-metallic inclusions in the cast product, the cast strand is ruled immediately after solidification at a reduction rate of 0.5 to 2.0 mm/m.
  • the object of the present invention is to provide a method of continuously casting molten steel and hot forming the cast steel, which eliminates substantial cracking of the cast bar during the hot ruling process.
  • the present invention resides in a method of continuously casting molten steel and hot forming said cast metal in substantially its as-cast condition at a hot-forming temperature by a plurality of substantial compressions, which method includes,
  • said light compressions comprise a first 7% reduction of the cross-section of said metal followed by at least one additional 7% reduction along an axis of compression 60° removed from the axis of said immediately prior 7% reduction.
  • the invention is applicable to both low and high alloy steels.
  • the present invention makes it possible to hot form the cast bar at a hot-forming temperature into a product having a relatively small cross-sectional area by a substantial reduction of the cross-sectional area of the cast bar which would be such that the as-cast structure of the cast bar would be expected to cause the cast bar to crack, by first forming a substantially uniform subgrain structure at least in the surface layers of the cast bar prior to later substantial reduction of the cross-sectional area of the cast bar, said substantially uniform subgrain structure being formed by relatively light deformations of the cast bar while at a hot-forming temperature.
  • the light deformations are of a magnitude (preferably less than 30% in total) which will not cause the cast bar to crack, but which in combination with the hot-forming temperature of the cast bar will cause the cast bar to have a substantially uniform subgrain or cell structure of a thickness sufficient (about 10% of total area) to produce a bar of increased ductility when compared to a bar produced by the prior art process, which substantially inhibits the initiation of micro and macro cracking that normally begin at the as-cast grain boundaries, thus preventing cracking of the cast bar (even when having relatively high percentage alloying elements) during the subsequent substantial deformations.
  • the substantially uniform subgrain structure of the surface provided by this invention allows substantial reduction of the cross-sectional area of the bar in a subsequent pass, even in excess of 30%, without cracking occurring and even though the cast bar has a relatively high amount of impurities or alloying elements.
  • the present invention allows a steel alloy cast bar having a cross-sectional area of 32 cm 2 (5 square inches), or more, and containing alloying elements, to be continuously hot formed into wrought rod having a cross-section area of 3 cm 2 (1/2 square inch), or less, without cracking.
  • the invention has a wide general utility since it can also be used with certain other relatively impure or alloyed metals as an alternative to the solution to the problem of cracking described in U.S. Patent No. 3,317,994, and U.S. Patent No. 3,672,430.
  • the present invention can be used for continuously casting and hot-forming steel containing a relatively high percentage of alloying elements without using specially shaped reduction rolls in the hot-rolling mill or other complex rolling procedures.
  • the cast steel bar can be efficiently hot-formed using fewer roll stands following conditioning of the cast metal by first forming the described substantially uniform fine grained, equiaxed or cell structure at the surface of the cast metal, then hot rolling the modified structure by successive heavy deformations.
  • the present invention can be applied to a wide range of steel alloys, including by way of example:
  • the continuous casting and hot-forming system (10) includes a casting machine (12) which includes a casting wheel (14) having a peripheral groove therein, a flexible band (16) carried by a plurality of guide wheels (17) which bias the flexible band (16) against the casting wheel (14) for a portion of the circumference of the casting wheel (14) to cover the peripheral groove and form a mold between the band (16) and the casting wheel (14).
  • a cooling system (not shown) within the casting machine (12) causes the molten metal to solidify in the mold and to exit the casting wheel (14) as a solid cast bar (20).
  • the cast bar (20) passes through a conditioning means (21), which includes roll stands (22) and (23).
  • the conditioning roll stands (22) and (23) lightly compress the bar to form a shell of substantially uniform fine or equiaxed grain structure at the surface of the bar (20).
  • the bar (20) is passed through a conventional rolling mill (24), which includes roll stands (25), (26), (27) and (28).
  • the roll stands of the rolling mill (24) provide the primary hot forming of the cast bar by compressing the conditioned bar sequentially until the bar is reduced to a desired cross-sectional size and shape.
  • the grain structure of the cast bar (20) as it exits from the casting machine (12) is shown in Fig. 2.
  • the molten metal solidifies in the casting machine in a fashion that can be columnar, or equiaxed, or both, depending on the super heat and cooling rate.
  • This as-cast structure can be characterized by grains (30) extending radially from the surfaces of the bar (if columnar) and separated from each other by grain boundaries (31). Most of the alloying elements present in the cast bar are located along the grain and dendrite boundaries (31).
  • the impurities along the boundaries (31) of the cast bar (20) would usually cause the cast bar to crack at the boundaries upon deformation by the roll stands of the rolling mill (24).
  • the conditioning means (21) prevents such cracking by providing a sequence of preliminary light compressions as shown in Fig. 3 and Fig. 4, wherein the result of a compression is shown and the previous shape of the cast bar is shown in broken lines.
  • Fig. 3 shows the result of a 7% reduction provided by the roll stand (22) along a horizontal axis of compression (33).
  • the columnar and/or equiaxed as-cast grain structure of the cast metal has been formed into a layer of substantially uniform fine grained, equiaxed or cell structure (35) covering a portion of the surface of the cast bar (20).
  • the interior of the bar may still have an as-cast structure.
  • Fig. 4 the bar (20) has been subjected to a second 7% reduction by the roll stand (23) along a vertical axis of compression (33) perpendicular to the axis of compression of roll stand (22).
  • the volume of substantially uniform fine grained, equiaxed or cell structure (35) now forms a shell (36) around the entire surface of the bar (20), although the interior of the bar retains some as-cast structure.
  • the formation of the shell may be accomplished by a conditioning means comprising any number of roll stands, preferably at least two, or any other type of forming tools, such as extrusion dies, multiple forging hammers, etc., so long as the preliminary light deformation of the metal results in a substantially uniform fine grained, equiaxed or cell structure covering substantially the entire surface of the bar, or at least the areas subject to cracking.
  • a conditioning means comprising any number of roll stands, preferably at least two, or any other type of forming tools, such as extrusion dies, multiple forging hammers, etc.
  • the individual light deformations should be between 5-25% reduction so as not to crack the bar during conditioning.
  • the total deformation provided by the conditioning means (21) must provide a shell (36) of sufficient depth (at least about 10%) to prevent cracking of the bar during subsequent deformation of the bar when passing through the roll stands (25-28) of the rolling mill (24).
  • the shape of the compressing surfaces in the roll stands (22) and (23) may be designed to avoid excessive compression of the corner areas as compared to the other surfaces of the cast bar, so that cracking will not result at the corners.
  • Fig. 5 shows a cross-section (20) following a substantial reduction of the cross-sectional area by the first roll stand (25) of the rolling mill (24).
  • the remaining as-cast structure in the interior of the bar (20) has been transformed into a uniform fine grained, equiaxed or cell structure (35).
  • the method of the present invention allows continuous casting and rolling of relatively high percentage alloy steel, such as molybdenum and tungsten containing steels and austenitic steel alloys without cracking the bar. Furthermore, cracking is prevented throughout the hot-forming temperature range of the metal. Thus, the same casting and hot-forming apparatus may be used to produce steel alloys of varying purities and alloying elements depending on the standards which must be met for a particular product.
  • relatively high percentage alloy steel such as molybdenum and tungsten containing steels and austenitic steel alloys
  • elliptically shaped rolling channels may be provided for all of the roll stands (22), (23), and (25-28) in order to provide optimal tangential velocities of the rolls in the roll stands with respect to the cast metal, as disclosed in U.S. Patent No. 3,317,994.
  • such measures are usually not needed to avoid cracking if the present invention is practised as described herein on metals having alloy levels as described above.
  • the roll stands of the conditioning means (21) may be either a separate component of the system or may be constructed as an integral part of a rolling mill.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Metal Rolling (AREA)
  • Forging (AREA)

Claims (22)

1. Verfahren zum Stranggießen von flüssigem Stahl und zum Warmumformen dieses Gußmetalls, im wsentlichen im gegossenen Zustand bei Warmumformtemperatur, durch mehrfaches starkes Verdichten, wobei nach dem Gießen des Metalls und vor dem starken Verdichten desselben ein im wesentlichen gleichmäßiges, feinkörniges oder gleichgerichtetes Gefüge zumindest an der Oberfläche des genannten Metalls durch wenigstens eine leichte Vorverdichtung des Metalls gebildet wird, dadurch gekennzeichnet, daß die leichten Verdichtungsvorgänge eine erste siebenprozentige Querschnittsverminderung des Metalls gefolgt von wenigstens einer weiteren siebenprozentigen Verminderung längs einer Verdichtungsachse umfassen, die um 60° zur Achse der genannten, unmittelbar vorausgehenden siebenprozentigen Reduzierung versetzt ist.
2. Verfahren nach Anspruch 1, wobei das Metall eine niedriggekohlte Stahllegierung 1015 (SAE) ist.
3. Verfahren nach Anspruch 1, wobei das Metall eine mitteigekohlte Stahllegierung 1045 (SAE) ist.
4. Verfahren nach Anspruch 1, wobei das Metall eine hochgekohlte Stahllegierung 1095 (SAE) ist.
5. Verfahren nach Anspruch 1, wobei das Metall eine Automaten-Kohlenstoffstahllegierung 1151 (SAE) ist.
6. Verfahren nach Anspruch 1, wobei das Metall eine korrosionsbeständige und kriechfeste Stahllegierung A 200 (ASTM) ist.
7. Verfahren nach Anspruch 1, wobei das Metall eine Silizium-Federstahllegierung 9259 (SAE) ist.
8. Verfahren nach Anspruch 1, wobei das Metall eine Kugellager-Stahllegierung 52100 ist.
9. Verfahren nach Anspruch 1, wobei das Metall eine martensitische nichtrostende Werkzeugstahllegierung 440 C ist.
10. Verfahren nach Anspruch 1, wobei das Metall eine austenitische nichtrostende Stahllegierung 304 ist.
11. Verfahren nach Anspruch 1, wobei das Metall eine austenitische nichtrostende Stahllegierung 310 ist.
12. Verfahren nach Anspruch 1, wobei das Metall eine schweißbare, nichtrostende Stahllegierung 348 ist.
13. Verfahren nach Anspruch 1, wobei das Metall eine ferritische Automatenstahllegierung 430 F (SE) ist.
14. Verfahren nach Anspruch 1, wobei das Metall eine Motorventil-Stahllegierung 14Cr-14Ni-2W ist.
15. Verfahren nach Anspruch 1, wobei das Metall eine aushärtbare Stahllegierung 17-7 PH ist.
16. Verfahren nach Anspruch 1, wobei das Metall eine Werkzeugstahllegierung 07 ist.
17. Verfahren nach Anspruch 1, wobei das Metall eine Werkzeugstahllegierung D5 ist.
18. Verfahren nach einem der Ansprüche 1 bis 17, wobei das genannte starke Verdichten nach der umformung des im wesentlichen gleichmäßigen, feinkörnigen oder gleichgerichteten Gefüges eine Vorverdichtung einschließt, die eine mindestens dreißigprozentige Querschnittsreduzierung des Metalls bewirkt.
19. Verfahren nach einem der Ansprüche 1 bis 18, wobei die leichten Vedichtungen insgesamt zu einer Querschnittsreduzierung des Metalls von weniger als 30 % führen.
20. Verfahren nach einem der Ansprüche 1 bis 19, dadurch gekennzeichnet, daß die Vielzahl leichter, aufeinanderfolgender Vorverdichtungen des genannten Strangs den Querschnitt des genannten Strangs insgesamt um weniger als 30% reduzieren, daß der Strang durch einfache Verdichtung des Strangs derart umgeformt wird, daß sein Querschnittsbereich um wenigstens 40% reduziert wird, und daß der Strang durch eine Vielzahl aufeinanderfolgender Verdichtungsvorgänge umgeformt wird, bei denen der Querschnitt des genannten Strangs jeweils soweit verändert wird, wie es erforderlich ist, um ein warmverformtes Erzeugnis mit einem festgelegten Querschnitt zu erzielen.
21. Verfahren nach Anspruch 20, wobei die Bearbeitung des Strangs das Durchführen des Strangs zwischen den Walzen einer Vielzahl aufeinanderfolgender Walzgerüste einschließt.
22. Verfahren nach Anspruch 21, wobei die Warmumformung des Strangs das Durchführen des Strangs durch aufeinanderfolgende Walzgerüste eines Walzwerks einschließt.
EP83902518A 1982-02-04 1983-02-04 Verfahren zur warmverformung von metallen, die beim walzen rissanfällig sind Expired EP0105368B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US34588582A 1982-02-04 1982-02-04
US345885 1999-07-01

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EP0105368A1 EP0105368A1 (de) 1984-04-18
EP0105368A4 EP0105368A4 (de) 1984-07-03
EP0105368B1 true EP0105368B1 (de) 1988-06-01

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GB (1) GB2124939B (de)
WO (1) WO1983002783A1 (de)

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Publication number Priority date Publication date Assignee Title
GB9014437D0 (en) * 1990-06-28 1990-08-22 Holton Machinery Ltd Continuous casting and extruding
TW297788B (de) * 1994-12-15 1997-02-11 Sumitomo Metal Ind
DE19915624A1 (de) * 1999-04-03 2000-10-05 Sms Demag Ag Verfahren und Anordnung zur kontinuierlichen Herstellung von Fertigprofilen aus Metall

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2059306A (en) * 1979-10-01 1981-04-23 Southwire Co Method and apparatus for continuously casting and hot-forming copper

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1816849C3 (de) * 1968-12-24 1973-12-13 Demag Ag, 4100 Duisburg Verfahren zum Stranggießen und anschließendem Walzen aus der Gieß hitze von Stahl
AT291898B (de) * 1969-05-09 1971-08-10 Voest Ag Verfahren zur Bearbeitung eines Stahlgußstranges
JPS5916862B2 (ja) * 1973-03-26 1984-04-18 日本鋼管株式会社 連続鋳造法
DE2441795C2 (de) * 1974-08-31 1982-12-09 Kabel- und Metallwerke Gutehoffnungshütte AG, 3000 Hannover Endloses metallisches Gießband für die Gießnut eines Gießrades zum Stranggießen
GB1596395A (en) * 1977-12-14 1981-08-26 Jernkontoret Forskningsavdelni Method of continuous casting of steels or metal alloys with segregation tendancy and apparatus for carrying out the method
JPS5939225B2 (ja) * 1978-02-13 1984-09-21 日本鋼管株式会社 鋼の連続鋳造法
JPS6037849B2 (ja) * 1979-07-12 1985-08-28 動力炉・核燃料開発事業団 クロム・モリブデン鋼の耐脱炭処理方法
US4354880A (en) * 1979-10-01 1982-10-19 Southwire Company Method of forge-conditioning non-ferrous metals prior to rolling

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2059306A (en) * 1979-10-01 1981-04-23 Southwire Co Method and apparatus for continuously casting and hot-forming copper

Also Published As

Publication number Publication date
EP0105368A4 (de) 1984-07-03
WO1983002783A1 (en) 1983-08-18
GB8326523D0 (en) 1983-11-02
EP0105368A1 (de) 1984-04-18
GB2124939A (en) 1984-02-29
GB2124939B (en) 1986-02-05

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