US3877684A - Continuous annealing furnace - Google Patents

Continuous annealing furnace Download PDF

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Publication number
US3877684A
US3877684A US432246A US43224674A US3877684A US 3877684 A US3877684 A US 3877684A US 432246 A US432246 A US 432246A US 43224674 A US43224674 A US 43224674A US 3877684 A US3877684 A US 3877684A
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US
United States
Prior art keywords
zone
strip
water
quenching
cooling zone
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
US432246A
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English (en)
Inventor
Takao Kurihara
Nobuo Tanaka
Toru Yamagishi
Kazuhide Nakaoka
Kenzi Araki
Kozi Iwase
Haruo Kubotera
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.)
JFE Engineering Corp
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Nippon Kokan Ltd
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Assigned to MANUFACTURERS HANOVER reassignment MANUFACTURERS HANOVER SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HORSEHEAD INDUSTRIES, INC., A DE CORP.
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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
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • C21D9/573—Continuous furnaces for strip or wire with cooling
    • 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
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire

Definitions

  • the present invention relates to improvements of a continuous annealing furnace comprising a recrystallization heating zone, a rapid cooling zone, a carbon precipitation treating zone and a final cooling zone, and more particularly, a new rapid zone divided into a gasjet cooling zone and water-quenching zone and an alternate path for the travelling steel strip is provided parallel with said water-quenching zone.
  • Continuous annealing art for cold rolled mild steel strip was developed for a mother steel of tinplating and has been used widely in the field.
  • Such a conventional art of continuous annealing usually comprises a recrystallization heating zone, a slow cooling zone, and the final cooling zone which offers an extremely short annealing time and uniform materials.
  • the art is defective in that the steel sheet after annealing was 1. hard,
  • the present invention has been developed to obtain the highest mechanical properties of steel sheet by a continuous annealing process with ease and stability.
  • the features of the present invention lie in the dividing of a rapid cooling zone following a carbon precipitation treating zone into a gas-jet cooling zone and a waterquenching zone and the providing of an alternate path for the travelling strip parallel with said water-quenching zone.
  • An object of the present invention is to provide improved continuous annealing facilities wherein passage of a travelling steel strip is changeable according to the required rapid cooling rate.
  • Another object of the present invention is to provide improved continuous annealing facilities capable of performing the most suitable heat cycle, including the required rapid cooling rate to obtain excellent mechanical properties.
  • FIG. I shows a fundamental structure of the continuous annealing furnace according to the present invention
  • FIG. 2 is a schematic view of the inner structure for the gas-jet cooling zone in FIG. 1;
  • FIG. 3 shows an outline of the water-quenching zone and an alternate path provided parallel with said zone in FIG. 1.
  • FIG. 1 A strip 1 is fed out of pay-off reel 2 and enters cleaning line 3. Although not shown, there are usually provided a cutter and a welder between said pay-off reel 2 and said cleaning line 3. In said cleaning line, such impurities as oils used in a cold reducing operation are removed from the strip 1.
  • the strip 1 is then made to pass through a looping tower 4 and goes into recrystallization heating zone 5.
  • the strip is heated up to 7 [0C. or thereabout and plastic strain caused by said cold reducing operation is removed therefrom.
  • the strip is then maintained at about the same temperature for a suitable period of time in order to encourage growth of recrystallized grains and solution of carbon from out of carbide in the steel.
  • the strip 1 then enters gas-jet cooling zone 6 which is one component of the present invention.
  • the strip in the said cooling zone is forcibly cooled down to the required temperature by the jet stream of atmospheric gas, at which time the waterquenching is started in the following stage.
  • the strip is cooled by the jet stream of the said atmospheric gas to a temperature of 500 to 600C. at which time said water-quenching is started.
  • a rate of above 200C./sec. is used for the travelling strip. Such a high rate quench will cause said strip to reach room temperature instantly.
  • the strip 1 is then processed through pickling, neutralizing, rinsing and drying and then is sent into carbon precipitation treatment zone 8. In this zone, said strip is reheated to a temperature of 400 to 500C.
  • the strip 1 thus processed enters final cooling zone 9 and is cooled down to room temperature and is subjected to a light reduction of about 1 percent by temper rolling stand 11 via a looping tower l and then finally coiled by the tension reel 12.
  • FIG. 2 one example of the inner structure of said gas-jet cooling zone 6 is illustratively shown in FIG. 2.
  • the strip I sent into said gas-jet cooling zone as it comes out of the recrystallization heating zone changes its direction by helper rools 13 and travels between gasjet headers 14.
  • the jet stream of atmospheric gas being jetted from a group of orifices 15, which is provided on said headers with an interval therebetween, cools the strip down to a predetermined temperature at which time the water-quenching is started.
  • the strip then enters the water-quenching zone 7 via seal rolls 16.
  • the atmospheric gas-jet being jetted to the strip 1 is exhausted out of the zone by duct pipe 17 and is cooled to about the room temperature by a gas cooler (not shown) and pressurized by a blower (not shown) and again introduced into the said headers 14.
  • dampers 18 provided at the inlet of the said headers 14, which act to control the gas flow. Control of the gas flow by the said dampers l8 will facilitate the control of cooling rate of said travelling strip 1.
  • the lower limit of the cooling rate by the atmospheric gasjet naturally is determined by the production efficiency as a continuous annealing line.
  • the upper limit thereof is automatically determined by the cooling efficiency of the atmospheric gas being used.
  • the scale of said continuous annealing time is determined by the distribution of time to the respective zones of said line while consideration is given to quality of materials.
  • the selection of an optimum cooling rate within such upper and lower limits may be arbitrarily made depending upon thickness of the travelling strip, by the control of the said dampers every time a need arises.
  • the present invention as heretofore explained, it is readily possible to obtain the heat cycle (as aforementioned) of the continuous annealing process which will impart the same degree of press formability as that obtained from the ordinary batch type annealing.
  • the temperature of the strip at the delivery side of said recrystallization heating zone is set up at 700C.
  • the temperature at the entry side of said water-quenching zone 7 is set up to 550C.: the difference between the temperatures is I50C.
  • annealing capacity of the employed continuous annealing furnace is 60 t/hr or thereabout and a strip of 0.8 mm thickness X 1,000 mm width was passed through the line, then the speed thereof is about 3 m/min.
  • the quenching system in the present invention comprises fundamentally a gas-jet cooling zone and a water-quenching zone.
  • a temperature of 500 to 600C. should be given as the best suited requirements for starting quenching.
  • the same degree of utility may not be expected of every thickness of annealing strips. That is to say, this is incomparably effective for a strip having more than about 0.6 mm thickness, but a strip with a thickness thinner than the above, i.e. one with 0.5 mm thickness, causes rapid appearances of defective shapes. Such defects as herein mentioned appear as a pocket-like shape and are confirmed to have been caused by the uneven quenching.
  • the present invention provides an alternate path parallel to a water-quenching zone through which the strip can be passed without going through said water quenching zone. Accordingly, the gas-jet cooling zone 6 and carbon precipitation treatment zone 8 are connected directly with each other. Such an example is shown in FIG. 3.
  • the travelling strip l at the delivery side of the gas-jet cooling zone 6 is changed in respect of its directions by helper rolls l9 and enters protective duct and then is sent to the carbon precipitation treatment zone 8 directly. Numerous experiments have confirmed that it is possible to obtain another optimum quenching rate of above C./sec, thus having eliminated any fears that this was not possible.
  • the temperature at which quenching is started should be selected from among the range of 650 to 850C. the case being different from the use of the said water-quenching zone. This temperature leads to the setting up of the recrystallization heating temperature and is easily realizable.
  • the treatment temperature of below 500C. and about 350C. are considered optimum. For instance, when said rapid cooling was to be started at 700C. and the temperature at the entry side of the carbon precipitation treatment zone 8 was to be made 490C., said rapid cooling range in said gas-jet cooling zone will be 210C.
  • a continuous annealing furnace for steel strip comprising a recrystallization heating zone, a rapid cooling zone, a carbon precipitation treating zone and a final cooling zone
  • improved facilities characterized in that said rapid cooling zone is divided into a gas-jet cooling zone and a water-quenching zone and an alternate path for said steel strip is provided parallel with said water-quenching zone such that the said strip may by-pass the said water quenching zone if necessary for a required rapid cooling rate.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
US432246A 1973-01-11 1974-01-10 Continuous annealing furnace Expired - Lifetime US3877684A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP556373A JPS535607B2 (enrdf_load_stackoverflow) 1973-01-11 1973-01-11

Publications (1)

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US3877684A true US3877684A (en) 1975-04-15

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US432246A Expired - Lifetime US3877684A (en) 1973-01-11 1974-01-10 Continuous annealing furnace

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US (1) US3877684A (enrdf_load_stackoverflow)
JP (1) JPS535607B2 (enrdf_load_stackoverflow)
BE (1) BE809624A (enrdf_load_stackoverflow)
DE (1) DE2401381C3 (enrdf_load_stackoverflow)
ES (1) ES422145A1 (enrdf_load_stackoverflow)
FR (1) FR2213983B1 (enrdf_load_stackoverflow)
GB (1) GB1435651A (enrdf_load_stackoverflow)
NL (1) NL155052B (enrdf_load_stackoverflow)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3950192A (en) * 1974-10-30 1976-04-13 Monsanto Company Continuous carburizing method
US4065329A (en) * 1975-01-17 1977-12-27 Centre De Recherches Metallurgiques-Centrum Voor Research In De Metallurgie Continuous heat treatment of cold rolled steel strip
DE2822430A1 (de) * 1977-05-24 1978-12-07 Centre Rech Metallurgique Verfahren zur kontinuierlichen waermebehandlung
EP0031012A1 (en) * 1979-10-31 1981-07-01 Kawasaki Steel Corporation Steel strip continuous annealing apparatus
US4358093A (en) * 1979-10-31 1982-11-09 Kawasaki Steel Corporation Steel strip continuous annealing furnace
US4363471A (en) * 1979-10-31 1982-12-14 Kawasaki Steel Corporation Steel strip continuous annealing apparatus
US4374682A (en) * 1979-02-02 1983-02-22 Nippon Steel Corporation Process for producing deep-drawing cold rolled steel strips by short-time continuous annealing
US4436292A (en) 1981-02-24 1984-03-13 Sms Schloemann-Siemag Ag System for the treatment of a continuous metal web
US4455136A (en) * 1981-06-29 1984-06-19 Chugai Ro Co., Ltd. Floating equipment and floating-type heat treating furnace for striplike works
US4501553A (en) * 1981-06-29 1985-02-26 Chugai Ro Co., Ltd. Floating equipment and floating-type heat treating furnace for striplike works
US4618379A (en) * 1982-09-21 1986-10-21 Roberto Bruno Method for the continuous annealing of steel strips
WO2010049600A1 (fr) * 2008-10-31 2010-05-06 Siemens Vai Metals Technologies Sas Four pour une installation de traitement thermique d'une bande d'acier en défilement continu et procédé associé

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52144331A (en) * 1976-05-28 1977-12-01 Nippon Kokan Kk Continuous annealing device
AU518681B2 (en) * 1979-12-05 1981-10-15 Nippon Steel Corporation Continuously annealing a cold-rolled low carbon steel strip
US4417720A (en) * 1979-12-12 1983-11-29 Centre De Recherches Metallurgiques Continuous heat treatment plant for steel sheet
CA1152870A (en) * 1979-12-24 1983-08-30 Hiromitsu Naito Process for continuously annealing of a cold rolled steel strip
DE3114412C1 (de) * 1981-04-09 1989-03-16 Klöckner-Werke AG, 4100 Duisburg Anlage zum kontinuierlichen Behandeln von Feinblech
DE102015001438A1 (de) 2015-02-04 2016-08-18 Bernhard Engl Flexible Wärmebehandlungsanlage für metalisches Band
DE102016011047A1 (de) 2016-09-13 2018-03-15 Sms Group Gmbh Flexible Wärmebehandlungsanlage für metallisches Band in horizontaler Bauweise

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3058840A (en) * 1959-04-16 1962-10-16 Electric Furnace Co Induction strip heating apparatus
US3262688A (en) * 1965-06-03 1966-07-26 Midland Ross Corp Jet convection heat transfer
US3323577A (en) * 1965-05-05 1967-06-06 Olin Mathieson Process for cooling metal
US3752459A (en) * 1969-12-16 1973-08-14 Nippon Kokan Kk Continuous annealing facilities for drawing steel strip

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3058840A (en) * 1959-04-16 1962-10-16 Electric Furnace Co Induction strip heating apparatus
US3323577A (en) * 1965-05-05 1967-06-06 Olin Mathieson Process for cooling metal
US3262688A (en) * 1965-06-03 1966-07-26 Midland Ross Corp Jet convection heat transfer
US3752459A (en) * 1969-12-16 1973-08-14 Nippon Kokan Kk Continuous annealing facilities for drawing steel strip

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3950192A (en) * 1974-10-30 1976-04-13 Monsanto Company Continuous carburizing method
US4065329A (en) * 1975-01-17 1977-12-27 Centre De Recherches Metallurgiques-Centrum Voor Research In De Metallurgie Continuous heat treatment of cold rolled steel strip
DE2822430A1 (de) * 1977-05-24 1978-12-07 Centre Rech Metallurgique Verfahren zur kontinuierlichen waermebehandlung
US4374682A (en) * 1979-02-02 1983-02-22 Nippon Steel Corporation Process for producing deep-drawing cold rolled steel strips by short-time continuous annealing
EP0031012A1 (en) * 1979-10-31 1981-07-01 Kawasaki Steel Corporation Steel strip continuous annealing apparatus
US4358093A (en) * 1979-10-31 1982-11-09 Kawasaki Steel Corporation Steel strip continuous annealing furnace
US4363471A (en) * 1979-10-31 1982-12-14 Kawasaki Steel Corporation Steel strip continuous annealing apparatus
US4436292A (en) 1981-02-24 1984-03-13 Sms Schloemann-Siemag Ag System for the treatment of a continuous metal web
US4455136A (en) * 1981-06-29 1984-06-19 Chugai Ro Co., Ltd. Floating equipment and floating-type heat treating furnace for striplike works
US4501553A (en) * 1981-06-29 1985-02-26 Chugai Ro Co., Ltd. Floating equipment and floating-type heat treating furnace for striplike works
US4618379A (en) * 1982-09-21 1986-10-21 Roberto Bruno Method for the continuous annealing of steel strips
WO2010049600A1 (fr) * 2008-10-31 2010-05-06 Siemens Vai Metals Technologies Sas Four pour une installation de traitement thermique d'une bande d'acier en défilement continu et procédé associé

Also Published As

Publication number Publication date
FR2213983A1 (enrdf_load_stackoverflow) 1974-08-09
BE809624A (fr) 1974-05-02
DE2401381C3 (de) 1978-05-18
ES422145A1 (es) 1976-04-16
DE2401381B2 (de) 1975-02-20
GB1435651A (en) 1976-05-12
DE2401381A1 (de) 1974-07-25
NL7400325A (enrdf_load_stackoverflow) 1974-07-15
JPS4993206A (enrdf_load_stackoverflow) 1974-09-05
FR2213983B1 (enrdf_load_stackoverflow) 1978-12-08
NL155052B (nl) 1977-11-15
JPS535607B2 (enrdf_load_stackoverflow) 1978-03-01

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