US3710608A - Method for heating unfinished tellurium-containing steel articles before hot rolling - Google Patents

Method for heating unfinished tellurium-containing steel articles before hot rolling Download PDF

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Publication number
US3710608A
US3710608A US00094282A US3710608DA US3710608A US 3710608 A US3710608 A US 3710608A US 00094282 A US00094282 A US 00094282A US 3710608D A US3710608D A US 3710608DA US 3710608 A US3710608 A US 3710608A
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Prior art keywords
furnace
gas
blanket
exit
recited
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US00094282A
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English (en)
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R Hentz
G Henger
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Inland Steel Co
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Inland Steel Co
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    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent 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
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S72/00—Metal deforming
    • Y10S72/70—Deforming specified alloys or uncommon metal or bimetallic work

Definitions

  • Combs Attorney-Merriam, Marshall, Shapiro & Klose 57 ABSTRACT Heating tellurium-containing steel billets, before hot rolling, by moving the billets along a path in a furnace having an oxidizing atmosphere. Providing and maintaining a gas blanket around the billets to protect them from surface oxidation along the hotter portions of the path. Combusting the blanket gas at a cooler portion of the path before the gas is exhausted from the furnace.
  • the present invention relates generally to methods for heating unfinished tellurium containing steel articles, such as billets, prior to hot rolling, and more particularly to a method for heating these articles in a manner which deters surface tearing of the articles during hot rolling.
  • unfinished steel article includes not only billets, but also other intennediate steel shapes such as blooms.
  • tellurium to steel enhances the machinability of the steel, but steel containing tellurium undergoes a surface defect known as surface tearing, during hot rolling of the steel.
  • Surface tearing is manifest by small cracks on the surface of the article undergoing hot rolling. These cracks occur during hot rolling and are concentrated at the corners of bars having polygonal cross sections and at sharp locations in ovals being hot rolled into rounds. Surface tearing renders the finished article commercially unacceptable.
  • Surface tearing is to be distinguished from other types of surface defects, such as those manifest by cracks in the unfinished steel article as it exits from the reheating furnace, before hot rolling.
  • the unfinished articles Prior to the hot rolling of unfinished steel articles into finished articles such as rounds, hexagons, or other polygonal shapes, the unfinished articles are subjected to a reheating operation, which typically comprises moving the billets through an elongated furnace heated by burners. Surface tearing is influenced by this reheating operation which conventionally occurs in a furnace having an oxidizing interior atmosphere.
  • An oxidizing atmosphere is generally desirable from a fuel efficiency standpoint, but an oxidizing atmosphere oxidizes a surface layer on the article, and this results in complications which contribute to surface tearing of telluriumcontaining steels.
  • the unfinished, tellurium-containing steel articles move along a path in an elongated reheating furnace extending from a relatively cool furnace entry to a relatively hot furnace exit.
  • the steel articles are heated during this movement with several longitudinally spaced flames each originating at a respective burner located above the path.
  • a continuous blanket of gas (e.g., natural gas) is provided around the articles undergoing heating in the furnace, to protect the surface of the articles from oxidation.
  • This blanket extends from the furnace exit toward the furnace entry. At least one of the article-heating flames originates near the furnace exit.
  • the gas in the blanket is introduced into the furnace, also near the exit, beneath the flame there. The gas in the blanket moves upstream from the furnace exit toward the entry without substantial mixing of the blanket gas with other gas entering the furnace at the burner where the flame originates.
  • combusted gases are removed from the furnace at an exhaust opening located upstream of the exit; and the blanket gas is burned, in the furnace, before the blanket gas is exhausted. Burning of the blanket gas is conducted at a location in the furnace where the temperature is relatively low, compared to the temperature at the furnace exit, and where surface oxidation or scaling of the tellurium-containing steel article is not a significant problem.
  • the blanketgas is combusted by introducing oxygen into the furnace at a location between the exhaust opening of the furnace and the furnace exit (where the blanket gas is introduced).
  • the furnace is provided with a flame originating at a burner located between the exhaust opening and the location where the oxygen is introduced, to assure combustion of the blanket gas before it is exhausted. This prevents flame in the exhaust conduit leading from the furnace, as would take place if the blanket gas were not combusted before it left the furnace.
  • FIG. 1 is a diagrammatic view illustrating a furnace DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. 1, there is illustrated generally, at 10, an elongated furnace in which tellurium-containing steel billets 11 are heated prior to hot rolling. Billets 11 are moved along a furnace path 12 extending from a furnace entry 13 to an exit 14.
  • the billets are heated, as they move along path 12, by flames originating at a number of burners longitudinally spaced along path l2.
  • One flame l5 originates at a burner 25 located at the exit end 30 of furnace l0 and disposed above billets 11 on path 12.
  • Also located above path 12 are flames l6, l7 originating at respective burners 26, 27; and located below path 12 is flame l8 originating at burner 28.
  • the direction and length of the flames are controlled so that they do not impinge upon the surface of billets ll.
  • the flames are generated by the combustion of conventional fuel (e.g., natural gas) and oxygen (using either commercially pure oxygen or air), and com-- busted gases are exhausted through an exhaust opening 20, in the top of furnace 10, between entry 13 and the burner 27, in this particular embodiment the burner located closest to entry 13. Gases exhausted through exhaust opening 20 are carried away through an exhaust conduit 21.
  • conventional fuel e.g., natural gas
  • oxygen using either commercially pure oxygen or air
  • the atmosphere within furnace is generally slightly oxidizing.
  • the fuel to oxygen ratio on a stoichiometric basis, is generally about 0.95. This is desirable to assure combustion, in the furnace, of the maximum amount of combustible fuel. If all the fuel were not combusted within the furnace (e.g., some fuel being combusted in exhaust conduit 21) less than the full heating potential of the fuel would be realized in the furnace.
  • an oxidizing atmosphere in the furnace is desirable from a fuel efficiency standpoint, it contributes to the problem of surface tearing of telluriumcontaining steel billets during subsequent hot rolling.
  • a continuous blanket of gas is provided around billets 11, to protect the surface thereof from oxidation.
  • the gas in this blanket is introduced into the furnace at nozzle 22; and the blanket extends from furnace exit end 30 toward entry 13.
  • the blanket terminates just before that part of path 12 under flame 17.
  • the blanket gas is typically natural gas, such as methane, although higher hydrocarbons such as butane, tetrane, ethane and pentane may be used. Carbon monoxide is permissible but not as desirable as the hydrocarbons. Hydrogen should not be used because it is too explosive.
  • the blanket gas introduced at nozzle 22 does not rise to any substantial extent to intermingle with the gases introduced at burners 25-27 or nozzle 23 until the blanket gas is well upstream along path 12, adjacent burner 27 where the blanket gas is combusted with oxygen introduced at a nozzle 23, to be described subsequently.
  • the temperature of furnace 10 is hottest at exit end 30 and the temperature decreases gradually upstream along path 12 toward entry 13.
  • the furnace temperature at exit end 30 is typically in the range 2,2002,500F.
  • the billet temperature is typically in the range 2,l002,300F.
  • the furnace temperature is in the range l,8002,000F.
  • the billet temperature is in the range l,600-l ,700F.
  • the billets are subjected to maximum surface oxidation in the hottest parts of the furnace. As the furnace temperature decreases, there is a reduction in surface oxidation and its resultant adverse contribution to surface tearing during subsequent hot rolling. Therefore, it is important that the blanket of gas be maintained around billets 11 in the hottest part of the furnace, with the importance of blanket maintenance decreasing as the furnace temperature decreases.
  • the blanket gas is exhausted through exhaust opening 20 just as are the combusted gases resulting from the combustion of fuel and oxygen introduced at burners 25-28. Because of the heat in exhaust conduit 21, especially that portion adjacent exhaust opening 20, any unburned blanket gas exiting through exhaust opening 20 would combine with any excess oxygen or air exiting through exhaust opening 20 and would be burned in conduit 21, causing flames therein. This is undesirable, and, in accordance with the present invention, the blanket gas is combusted in furnace 10 before exiting through exhaust opening 20.
  • Combustion of the blanket gas is accomplished by introducing oxygen, at nozzle 23 located above path 12 between exit end 30 and exhaust opening 20.
  • the oxygen from nozzle 23 is injected downwardly toward and mixes with the gas blanketing billets 11. Because flame 17 is located between oxygen injection nozzle 23 and exhaust opening 20, flame l7 assures substantially complete combustion of the blanket gas and the oxygen before they reach exhaust opening 20. By preventing uncombusted blanket gases from passing through exhaust opening 20, the likelihood of combustion occurring in exhaust conduit 20 is reduced.
  • the blanket gas is composed of 98 percent methane and about 2 percent higher hydrocarbons, such as ethane.
  • the blanket gas is introduced at a rate in the range 40-80 cubic feet per minute.
  • the fuel is introduced at a rate of 2,000 cubic feet per minute and the air at a rate of 20,000 cubic feet per minute, a volume ratio of air to fuel of 10 to 1.
  • Oxygen introduced at nozzle 23 is introduced at a rate of about 500 cubic feet per minute.
  • Typical dimensions for furnace 10 are 45 feet wide and 100 feet long.
  • the vertical dimension between path 12 and furnace roof 19 vary from 3 feet high at the low point 32 of the roof and 12 feet high at the high point 33 of the roof.
  • a method for processing unfinished tellurium-containing steel articles so as to deter surface tearing during hot rolling comprising the steps of:
  • said flame originates adjacent the exit of the furnace
  • said burning is conducted at a location in the furnace where the temperature is relatively low compared to the temperature at said exit and where surface oxidation of the billets is not a significant problem.
  • a method as recited in claim 5 wherein said last- 10 recited step comprises:
  • the gas for the blanket being introduced into said furnace at a location below said flame.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
  • Furnace Details (AREA)
  • Tunnel Furnaces (AREA)
  • Harvesting Machines For Root Crops (AREA)
  • Metal Rolling (AREA)
US00094282A 1970-12-02 1970-12-02 Method for heating unfinished tellurium-containing steel articles before hot rolling Expired - Lifetime US3710608A (en)

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US9428270A 1970-12-02 1970-12-02

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US (1) US3710608A (no)
JP (1) JPS523325B1 (no)
AR (1) AR196484A1 (no)
AT (1) AT324387B (no)
AU (1) AU470302B2 (no)
BE (1) BE776027A (no)
BR (1) BR7107898D0 (no)
CA (1) CA940021A (no)
CH (1) CH545147A (no)
DE (1) DE2157512C3 (no)
DK (1) DK136256B (no)
ES (1) ES397586A1 (no)
FR (1) FR2117249A5 (no)
GB (1) GB1365718A (no)
IT (1) IT943131B (no)
LU (1) LU64360A1 (no)
NL (1) NL7116228A (no)
NO (1) NO133938C (no)
SE (1) SE381678B (no)
ZA (1) ZA717939B (no)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0045815A1 (en) * 1980-08-11 1982-02-17 Inland Steel Company Semi-finished steel article and method for producing same

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5582326A (en) * 1978-12-19 1980-06-21 Toshiba Corp Signal connection system
DE9313451U1 (de) * 1993-09-07 1993-11-04 Ipsen Industries International GmbH, 47533 Kleve Schutzgasofen
CN112893723A (zh) * 2021-02-08 2021-06-04 无锡透平叶片有限公司 一种钢锻件的锻前加热方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3287954A (en) * 1962-08-30 1966-11-29 Inland Steel Co Method for heating steel billets
US3345846A (en) * 1966-08-01 1967-10-10 Selas Corp Of America Metal heating
US3365922A (en) * 1965-02-01 1968-01-30 Inland Steel Co Method for producing hot-worked tellurium-containing steel article
US3382700A (en) * 1966-03-31 1968-05-14 Inland Steel Co Process for reducing surface checking during hot working of steel
US3399873A (en) * 1965-07-26 1968-09-03 B P Przemyslu Hutniczego Furnace for scaleless direct heating of metal charge destined to heattreatment
US3503240A (en) * 1966-08-01 1970-03-31 James R Lawler Heat treating method and apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3287954A (en) * 1962-08-30 1966-11-29 Inland Steel Co Method for heating steel billets
US3365922A (en) * 1965-02-01 1968-01-30 Inland Steel Co Method for producing hot-worked tellurium-containing steel article
US3399873A (en) * 1965-07-26 1968-09-03 B P Przemyslu Hutniczego Furnace for scaleless direct heating of metal charge destined to heattreatment
US3382700A (en) * 1966-03-31 1968-05-14 Inland Steel Co Process for reducing surface checking during hot working of steel
US3345846A (en) * 1966-08-01 1967-10-10 Selas Corp Of America Metal heating
US3503240A (en) * 1966-08-01 1970-03-31 James R Lawler Heat treating method and apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0045815A1 (en) * 1980-08-11 1982-02-17 Inland Steel Company Semi-finished steel article and method for producing same

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Publication number Publication date
GB1365718A (en) 1974-09-04
NO133938B (no) 1976-04-12
JPS523325B1 (no) 1977-01-27
AU3620771A (en) 1973-05-31
ZA717939B (en) 1972-08-30
AU470302B2 (en) 1976-03-11
LU64360A1 (no) 1972-06-19
AR196484A1 (es) 1974-02-06
CA940021A (en) 1974-01-15
DK136256C (no) 1978-02-13
DK136256B (da) 1977-09-12
ES397586A1 (es) 1974-06-16
IT943131B (it) 1973-04-02
CH545147A (fr) 1973-12-15
BE776027A (fr) 1972-03-16
NL7116228A (no) 1972-06-06
DE2157512B2 (de) 1978-08-17
BR7107898D0 (pt) 1973-05-17
FR2117249A5 (no) 1972-07-21
SE381678B (sv) 1975-12-15
DE2157512C3 (de) 1979-04-12
AT324387B (de) 1975-08-25
DE2157512A1 (de) 1972-06-08
NO133938C (no) 1976-07-21

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