US3648349A - Method for treating a hot-rolled metal body and the like - Google Patents

Method for treating a hot-rolled metal body and the like Download PDF

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Publication number
US3648349A
US3648349A US835359A US3648349DA US3648349A US 3648349 A US3648349 A US 3648349A US 835359 A US835359 A US 835359A US 3648349D A US3648349D A US 3648349DA US 3648349 A US3648349 A US 3648349A
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United States
Prior art keywords
hot
coating
chamber
powder
flaws
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Expired - Lifetime
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US835359A
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English (en)
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Georges Schaumburg
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Individual
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Individual
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Priority claimed from DE1771666A external-priority patent/DE1771666C2/de
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Publication of US3648349A publication Critical patent/US3648349A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B38/00—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/04—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing
    • B21B45/06—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing of strip material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/4981—Utilizing transitory attached element or associated separate material
    • Y10T29/49812—Temporary protective coating, impregnation, or cast layer
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49972—Method of mechanical manufacture with separating, localizing, or eliminating of as-cast defects from a metal casting [e.g., anti-pipe]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49972—Method of mechanical manufacture with separating, localizing, or eliminating of as-cast defects from a metal casting [e.g., anti-pipe]
    • Y10T29/49975—Removing defects
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/4998—Combined manufacture including applying or shaping of fluent material
    • Y10T29/49982—Coating
    • Y10T29/49986—Subsequent to metal working

Definitions

  • the present invention relates to a method of and an apparatus for treating a hot-formed metal body and, more particularly, a hot-rolled metal body.
  • the invention also relates to a method of and an apparatus for hot-rolling of steel bodies and to a technique for detecting surface flaws or defects thereon.
  • a heated ingot, billet, bloom or slab is passed between a plurality of pairs of rolls of successively narrowing spacing so that the slab or ingot is lengthened and narrowed. This operation is preferably carried out with the billet in a hot condition.
  • a more specific object is to provide such a method and apparatus which overcome the above-mentioned difficulties particular to hot-rolled metal bodies.
  • Still another object of this invention is to provide a method for protecting hot-rolled steel bodies against scaling and also to improve markedly the quality of hot-rolled steel bodies obtainable from a rolling mill.
  • the method involves the steps of hot-forming a steel body and, prior to any substantial formation of scale thereon or after an initial treatment of the hot slightly scaled body with a reducing agent, forming a thin flowable liquid-glass or enamel coating on the body. Upon hardening of this coating, it not only seals the surface against chemical attack and scaling, but (of even greater importance from the point of view of this aspect of the invention) itself is indicative of the presence of surface flaws as noted below. These flaws, not readily visible otherwise, can then be eliminated by conventional techniques.
  • This treatment chamber is fitted with at least one nozzle which is connected through at least one blower to a hopper containing the above-described powder.
  • the nozzle is formed with a Venturi restriction and a small pipe opening longitudinally into the nozzle is connected to a source of gas under pressure to accelerate the powder and project it out of the nozzle against the body.
  • An inert gas, a reducing gas, or simply air can be used as propellant.
  • the powder can be a mixture of oxides of silicon, magnesium, aluminum, and iron, along with metallic sodium, boron, or potassium, or a compound of these chemicals.
  • Zinc borate according to a further feature of the present invention, has proven useful in the enamel layer in that the final product is effectively zinc coated upon removal of the coating.
  • the coated and cooled body can be stripped of its temporary glassy coating, for instance in a straightening station, and subsequently recoated for greater permanence by spraying with paint, lacquer, a synthetic-resin protective coating, or the like.
  • a method is particularly advantageous in that the glassy coating is quite easy to remove from the body, i.e., more easily removed than the customary scale, so that the body can be completely processed in one continuous operation.
  • the body which can be a continuous rod, wire, sheet or the like, is simply passed through a fluidized bed of the above-described metal and metal-oxide powders to coat it.
  • the coating must be thin enough to rupture in the region of any flaws, or to allow the flaws to be seen through the coating, while being tough enough not to flake off immediately as the workpiece is transported.
  • a key feature of the present invention is the formation of a glasslike coating upon the surface of a hot-formed body while it is still in the heated condition and susceptible to sealing, of a relatively thin and brittle character upon cooling.
  • This enamel layer which may be composed of any conventional enameling composition, dispensed in the liquid or solid state and merely solidifiable on the body and/or fusible thereon utilizing the heat of the body, surprisingly is capable of providing a visible indication of surface flaws or defects in the body.
  • the enamel film ruptures, fractures or breaks in the presence of surface flaws, e.g., pits, striations, projections, contamination areas, cracking and similar defects, either as a consequence of thermal stress during cooling, or mechanical movement of various portions of the defect area, etc. or as a result of an inability to adhere effectively to these regions, thereby producing a fracture zone in the region of the defects.
  • This marking or indication of the defects permits the defective material to be removed or otherwise monitored to ensure that the finished product will be free from the flaws.
  • the enamel layer does not remain as tenaciously upon the body as would a slag layer or other scale-forming material, but rather can be broken away with ease as will be apparent hereinafter.
  • enamel and glasslike material While reference has been made above to enamel and glasslike material as capable of fulfilling the requirements of the present invention, it may be noted that numerous enamel compositions which are capable of melting at a wide range of temperatures including the temperatures at which the metal (steel) body emerges from the hot-forming stage, are known and may be used in accordance with the present invention as long as the material is applied to the body with a viscosity sufficiently low to enable the liquid material to flow into a uniform thin film coating the body.
  • This film which may have a thickness of the order of microns, e.g., 5-10 microns, may either be applied in the form of a liquid coating or glass or may be applied in a powder stream, e.g., designed to fuse to flow along the surface at the temperature of the body, but in either case will be a glassy substance.
  • this treatment is carried out in a tubular chamber enclosing the body and open at its ends-to permit the body to pass through the chamber.
  • the latter is provided with a configuration geometrically similar to that of the body, i.e., a chamber of circular cross section when the body is a continuously cast rod of circular cross section.
  • an important feature of this invention resides in the provision of reducing agents in the treatment process to eliminate any scale which may have been formed on the body prior to coating with the enamel layer.
  • the body may be treated with a reducing gas or reducing agents, e.g., sodium, potassium and like reducing metals may be employed, the reduction products and the oxidized metal compounds resulting from the reducing reaction being incorporated in the subsequently formed enamel coating.
  • a reducing gas or reducing agents e.g., sodium, potassium and like reducing metals may be employed, the reduction products and the oxidized metal compounds resulting from the reducing reaction being incorporated in the subsequently formed enamel coating.
  • scale layers when composed of the slag-formed present in metallurgical systems are of a glassy nature and are soluble in the glasslike enamel coating applied in accordance with the present invention.
  • the powders preferably in the form of a powder mixture of the character set forth above, it has been found to be advantageous to provide a tandem array of blowers, the first receiving a mixture of powders and air and constituting a loosening means whereby the powders are dispersed in the airstream to form a flowable mixture.
  • the powder/air mixture is accelerated to a high velocity and propelled to a discharge nozzle trained upon the hot-metal surface.
  • a venturi injector to which compressed air is fed to regulate the velocity of the powder/air mixture directed against the workpiece surface.
  • FIG. I is a perspective view of a rolling mill embodying the principles of the present invention.
  • FIG. 2 is a vertical section through the rolling mill of FIG. 1;
  • FIG. 3 is a perspective view of a continuous casting installation embodying the principles of the present invention.
  • FIG. 4 is a vertical section through the installation of FIG. 3;
  • FIG. 5 is a vertical section through another apparatus embodying the present invention.
  • FIGS. 6 and 7 are sections through a metal body at two separate stages in its treatment according to the present invention.
  • a slab or sheet 3 is formed between two rolls 23 and 23' of a last rolling stage 1 of a rolling train. This slab 3 emerges from between these rolls 23 and 23' in a very hot, solid and relatively scale-free condition. It is transported by driven rollers 2 through a chamber 22 where it is subjected to the reduction effects of a reducing gas, e.g., hydrogen, carbon monoxide, methane or mixtures thereof, to remove any slight scale formations which might have come into being thereon.
  • a reducing gas e.g., hydrogen, carbon monoxide, methane or mixtures thereof
  • a powder P which is a mixture of reducing-metal and metal oxide particles that fuse on the surface and form a very hard, inflexible enamellike glassy coating (see FIG. 6).
  • other substances e.g., zinc
  • zinc borate another substance which produces the desired coating or alloying substance in situ.
  • FIG. 6 shows the slab 3 with its hardened coatings C.
  • the slab 3 passes through a straightening station 6 where three rollers 28a c bend the slab 3 sufficiently to break free the coating C. Due to the regularity of this coating, it is easily removed. This coating is, however, very tight on the metal body 3, since the surface of the body 3 reacts to some extent with the wetted powders P to form the coating C.
  • a coating station 7 having a plurality of nozzles 7a sprays a more flexible protective coating M, e.g., paints, upon the surface of the cooled slab 3.
  • This coating M is shown in FIG. 7.
  • any flaws as shown at F in FIG. 6, will not be covered; the coating C will break in the region of these flaws F. Thus, an observer in the region 5 can clearly see them and mark the slab 3 in this region so that it can be later discarded.
  • FIGS. 3 and 4 show an alternative embodiment of the present invention.
  • molten metal is poured from a ladle 16 into a funnel la on top of a mole 1' of a continuous casting installation.
  • a metal body in the form of a thick wire 3' leaves the base of this mold l and is bent through by driven rollers 3 of hyperbolic profile and through a chamber 22' similar to the chamber 22 of FIGS. 1 and 2.
  • a boxlike chamber 4' is equipped with two nozzles 18 and 8' connected through a powder-aerating apparatus to a hopper 11' just as in FIGS. 1 and 2, common reference numerals referring to common structure.
  • This wire 3 is here coated according to the method and principles set out in connection with FIGS. 1 and 2.
  • the enamel coating is not stripped off the wire 3', since it serves to protect the wire during shipping and handling, and relatively easily removed when desired. This coating also serves to accentuate and make more visible flaws in the surface of the wire 3', as described above for FIGS. l and 2.
  • FIG. 5 shows a further embodiment of the invention having in this case a treatment chamber 4".
  • a fluidized bed is formed around a continuous workpiece 3" reiding on rollers 2".
  • the workpiece 3" is very hot and relatively scale free.
  • a blower 21 having an output connected through a conduit 20b to the bottom of the chamber 4" and an input conduit 20a connected to the top of this chamber 4" serves to fluidize minute metallic and metallic oxide particles P fed into the chamber through a conduit connected to a hopper 11" above the chamber 4". In this way the workpiece 3 is very efficiently covered by the powder, so that it can move at high speeds through the chamber 4" and still be adequately coated.
  • a steel body is hot-formed and enters the treatment chamber at a temperature somewhat below its melting point. It is sprayed with a mixture of powders such that substantially equal parts of SiO AI..O Fe o CaO, MgO, Na, K, and B mixed with and carried by air strike the surface of the body. This mixture reduces the slight scale on the surface and fuses to form a glassy enamellike coating over the entire exterior of the body, the fused mixture flowing to cover all of its surface to a thickness on the order of say 5 to microns. As the body cools, the enamel coating breaks in the region of any flaws on it.
  • EXAMPLE B A steel wire is formed by rolling and enters a treatment chamber as above. In this chamber it is: sprayed with a powder whose prime constituent is zinc borate. The hard, enamellilce coating is formed as above. Then the body is fed through a straightening apparatus which removes the coating and is found to be zinc coated in the sense that zinc is alloyed with surface zones of the metal body.
  • a method of accenting and removing surface flaws in a hot metal body emerging in a substantially scale-free state from a forming stage comprising the steps of:
  • said forming stage is a rolling stage from which said body emerges continuously and said substance is a powder containing a reducing agent and applied to said body by blowing said powder thereagainst.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
  • Metal Rolling (AREA)
US835359A 1968-06-24 1969-06-23 Method for treating a hot-rolled metal body and the like Expired - Lifetime US3648349A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1771666A DE1771666C2 (de) 1968-06-24 1968-06-24 Verfahren und Vorrichtung zur Verbesserung der Erkennbarkeit von Oberflächenfehlern auf Walzgut durch Aufbringen emailähnlicher Uberzugsschichten

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US3648349A true US3648349A (en) 1972-03-14

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US835359A Expired - Lifetime US3648349A (en) 1968-06-24 1969-06-23 Method for treating a hot-rolled metal body and the like

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US (1) US3648349A (enrdf_load_stackoverflow)
BE (1) BE734967A (enrdf_load_stackoverflow)
CA (1) CA928158A (enrdf_load_stackoverflow)
FR (1) FR2013361A1 (enrdf_load_stackoverflow)
GB (1) GB1277755A (enrdf_load_stackoverflow)
NL (1) NL6909260A (enrdf_load_stackoverflow)
SE (1) SE342915B (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4281035A (en) * 1978-02-22 1981-07-28 Foseco International Limited Marking composition and method of using same
CN107578168A (zh) * 2017-09-05 2018-01-12 北京首钢冷轧薄板有限公司 一种用于缺陷库移植的方法、装置及电子设备
GB2570542A (en) * 2017-12-05 2019-07-31 British Steel Ltd Steel profile and method of processing steel
GB2571805B (en) * 2017-12-05 2020-12-16 Jingye Steel Uk Ltd Steel product

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5339935A (en) * 1976-09-24 1978-04-12 Nippon Steel Corp Method of and device for applying scale reforming agent to hot rolled steel band
IT1160196B (it) * 1983-02-24 1987-03-04 Dalmine Spa Procedimento di disossidazione a caldo di tubi metallici semilavorati

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2442485A (en) * 1944-06-24 1948-06-01 Frederick C Cook Method of descaling and coating hot-rolled ferrous metal
US2458715A (en) * 1944-08-25 1949-01-11 Thompson Prod Inc Method of preventing scaling
US2762115A (en) * 1952-01-29 1956-09-11 American Brass Co Protecting hot extruded metal
US3169310A (en) * 1959-06-01 1965-02-16 Inland Steel Co Vitreous enamel coatings

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2442485A (en) * 1944-06-24 1948-06-01 Frederick C Cook Method of descaling and coating hot-rolled ferrous metal
US2458715A (en) * 1944-08-25 1949-01-11 Thompson Prod Inc Method of preventing scaling
US2762115A (en) * 1952-01-29 1956-09-11 American Brass Co Protecting hot extruded metal
US3169310A (en) * 1959-06-01 1965-02-16 Inland Steel Co Vitreous enamel coatings

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4281035A (en) * 1978-02-22 1981-07-28 Foseco International Limited Marking composition and method of using same
CN107578168A (zh) * 2017-09-05 2018-01-12 北京首钢冷轧薄板有限公司 一种用于缺陷库移植的方法、装置及电子设备
GB2570542A (en) * 2017-12-05 2019-07-31 British Steel Ltd Steel profile and method of processing steel
GB2571805B (en) * 2017-12-05 2020-12-16 Jingye Steel Uk Ltd Steel product
GB2570542B (en) * 2017-12-05 2022-06-29 Inoxihp S R L Steel profile and method of processing steel

Also Published As

Publication number Publication date
BE734967A (enrdf_load_stackoverflow) 1969-12-01
GB1277755A (en) 1972-06-14
SE342915B (enrdf_load_stackoverflow) 1972-02-21
FR2013361A1 (enrdf_load_stackoverflow) 1970-04-03
NL6909260A (enrdf_load_stackoverflow) 1969-12-30
CA928158A (en) 1973-06-12

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