US3724826A - Method and apparatus for water quenching metal strips - Google Patents

Method and apparatus for water quenching metal strips Download PDF

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Publication number
US3724826A
US3724826A US00158968A US3724826DA US3724826A US 3724826 A US3724826 A US 3724826A US 00158968 A US00158968 A US 00158968A US 3724826D A US3724826D A US 3724826DA US 3724826 A US3724826 A US 3724826A
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United States
Prior art keywords
strip
water
slits
quenching
nozzle
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Expired - Lifetime
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US00158968A
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English (en)
Inventor
K Araki
T Kurihara
H Kubotera
K Nakaoka
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JFE Engineering Corp
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Nippon Kokan Ltd
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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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62—Quenching devices
    • C21D1/667—Quenching devices for spray quenching

Definitions

  • the present invention concerns continuous annealing of low carbon steel strips by shelf treatment, and more particularly to a method and an apparatus of cooling said strips efficiently.
  • the following annealing cycle is employed in manufacturing cold rolled low carbon steel strips; namely heating the cold rolled strips up to 700 800 C by radiation heating, quenching to a temperature of less than 500 C at a quenching rate of 500 2000 C/sec, maintaining at 400-500 C for 15 60 sec., and subjecting to forced air cooling until the temperature reaches the room (ambient) temperature.
  • the treatment of maintaining the strip at 400 500 C for 15 60 sec after quenching is hereinafter referred to as Shelf Treatment.
  • a vapor film is formed on the surface of the strip as it contacts the quenching liquid and damages the shape of the strip excessively. This causes inconvenience in tracking the moving strip.
  • the strip is instantly covered with a vapor film as it comes into contact with the quenching water, which film near the strip margins then rapidly disappears, the resultant further contact of the water with the strip producing nucleate boiling and rapid cooling of the margins.
  • a state of film boilding is maintained until the temperature reaches about 500 C.
  • the cooling speed is extremely slow compared to that at the margins.
  • a difference of more than 300 C is seen between the temperatures at the margins and at the center.
  • the termal stress due to such a difference is the cause for the inferior shapes such as waves. It was found out that when a jet stream of quenching water is brought into contact with the surface of the strip, the impact pressure with which the liquid is jetted onto the strip can positively eliminate the vapor film throughout the width of the strip and the strip can be uniformly cooled.
  • FIG. 1 is a graph showing the relation between the impact pressure of the quenching water on the strip surface and the difference in temperature between the center part of the strip and the margins thereof;
  • FIG. 2 shows a graph indicating the variation of the jet stream pressure with spacing between adjacent nozzles and spacing between the nozzle plates
  • FIG. 3 is a magnified diagram of the part indicated by black dots of the jet stream pressure in FIG. 2;
  • FIG. 4 is a diagram of continuous annealing apparatus using shelf treatment and apparatus of the present invention.
  • FIG. 5 and FIG. 6 are side and front views, respectively, of the quenching apparatus
  • FIG. 7 is a front view of the jet forming apparatus of FIGS. 5 and 6;
  • FIG. 8 is a vertical cross sectional view of the apparatus of FIG. 7.
  • FIG. 9 is a diagram showing the location of the two jet forming apparatuses in relation to the strip.
  • the relationship between the impact pressure of the jet stream on the strip surface (hereinafter referred to as the impact pressure) and the difference in temperature between the center and the margins of the strip is show in a graph in FIG. 1.
  • the sample used was 1.6 mm thick, 300 mm wide cold rolled steel sheet which had been subjected to a heating temperature of 710 .C.
  • the white dots indicate the temperature between the center part and a point 15 mm from the edge, and the black dots show the temperature difference between the center part and a point 45 mm from the edge. It can be seen that a pressure of 5 cm H O has some effect, but the graph indicates that a minimum pressure of 15 cm H O is necessary in order to secure a stabilized temperature difference of less than 100 C.
  • an optimum combination of individual spacing between the jets ofquenching water in sheet form, and the spacing between the nozzle plates should be determined in order to create a zone wherein the strip is continuously exposed to the quenching liquid in sheet form having an impact pressure of more than 15 cm H O for a sufficient period to cool the strip to a temperature below the temperature-known as the lower limit of the film boiling (500 C).
  • the length of such a zone is about 60 cm in the case of a line speed of I m/min for a strip having 0.8 mm thickness.
  • FIG. 2 indicates how impact pressure varies in dependence on the various combinations of the spacing between adjacent jet streams and the spacing between the nozzle plates.
  • the slit opening is 2 mm and the hydraulic pressure within the headers is 0.17 kg/cm.
  • FIG. 3 An example of the impact pressure distribution under the conditions corresponding to the black dots (a) to (d) in FIG. 2 is shown in FIG. 3.
  • FIG. 3(a) the distribution of the impact pressure under the aforegoing conditions at the point (a) in FIG. 2 is shown.
  • the present invention is based on the experimental results of the inventors and aims to offer a method of cooling and apparatus for use in continuous annealing of low carbon steel strips, using shelf treatment, and jetting the quenching water onto the saidstrips in the form of transverse sheets of pressurized water spaced along the direction of strip advancement.
  • the strip used is mild steel containing less than 0.06 wt percent carbon, the size being 0.06 1.6 mm thick and 600 1800 mm wide.
  • the line speed of the annealing furnace is 60 m/min to 300 m/min.
  • FIG. 4 The diagram showing the whole facilities for continuous annealing which enables the shelf treatment of this invention is shown in FIG. 4 wherein the steel strip 1 is delivered from the entry reel 2, grease is washed off in the cleansing tank 3, the strip is sent on to the heating zone 7 via a bridle roll 3, a looping tower 5, and a free looping part6. After the strip is heated up to 700 800 C in the said heating zone 7, it enters the soaking zone 8 wherein the temperature across the width of the strip is made uniform, and is then quenched to a temper'ature of less than 100 C in quenching apparatus 9. The thin scales on the strip surface formed during the cooling operation are washed with hydrochloric acid in the pickling tank 10.
  • the strip then is passed through water tankll, drying zone 12 and then to reheating zone 13 for heating up to the shelf annealing temperature of 400 500 C. After it has been maintained at the said temperature in the soaking zone 14 for 15 60 seconds, it is passed on to the looping pit 15, the free loop 16, and thebridle 17. to be coiled bythe tension reel 18.
  • the present invention apparatus is characterized in that it has an efficient cooling apparatus 9, the details of which are shown in the magnified views of FIGS. 5 and 6..
  • the strip 1 having passed through the soaking zone passes onto the seal rolls 19, and enters between the jet stream apparatus (which comprises the cooling apparatus of the present invention).
  • the strip is water quenched therein to a temperature of below 100 C, goes over the sink roll 21 and is then sent to the pickling tank.
  • the quenching water is fed to the jetting apparatus 20 by the water feed pipe 22 having a flexible part 23. After it impinges on the strip surface, the water flows away through a sluice 24 to the reservoir tank.
  • the jetting apparatus 20 is fixedly mounted on a slidable base 25 and the spaces between the nozzle sections may be arbitrarily adjusted by means of the handle 26.
  • FIGS. 7 and 8 Further details of the jetting apparatus 20 are shown in FIGS. 7 and 8.
  • the particular type shown in the Figures is one wherein one header projects more than two uniform sheets of water, each sheet of water extending across the strip width (hereinafter referred to as a box type header).
  • Thequenching liquid induced intothe two headers which are provided at symetrical corresponding positions on both sides of the strip 1, by means of the water feed pipe 22, is forced in the directions'indicated by arrows in the drawings by the baffle plate 27 and jetted through a group of slit nozzles 28 spaced apart in the, direction of strip advance and having rectangular orifices extending across the stripv width.
  • the baffle plate 27 acts to maintain the uniformity of each jet stream in the direction of its width as well as to equalize the strength of the jet stream.
  • the nozzle plate 29 is divided into a plurality of dismountable sections so that the distance between the slits, slit openings, and the direction of the jets are optionally selectable in accordance with the individual needs.
  • the said nozzle plate 29 is fixed to the header by means of the bolts 32 through the seat 30 and the fraine 31. Normally the nozzle plate used is 10 to 20 mm thick and the slit opening is about 1 to 3 mm. As is indicated by the impact pressure distribution diagram of FIG.
  • the impact pressure of the upper jet stream tends to be weakened by the effect of the jet stream of the more central streams
  • the opening of the upper slit is adjusted to be wider than that of the other, and the directions of the jet streams from the upper slits are deflected downward to increase their impact pressure. This will achieve a still better shape of the strip.
  • the hydraulic pressure within the header is measured by the pressure transformer 33 and is normally kept at 0.1 to 0.4 kglcm
  • a method in accordance with the present invention uses the quenching apparatus as hereinbefore described to quench the strip.
  • water jetting apparatus for quenching the strip is provided at corresponding symmetrical locations on both sides of the running strip with more than 40 mm intervals between the nozzle plates, and thesev jet the quenching water on both sides of the strip vto cool the strip to a temperature of less than 500 C under an impact pressure of 15 cm H O or more.
  • the spacing between adjacent nozzles in each nozzle'plate is less than that between the said nozzle plates.
  • Example I A cold rolled steel sheetof 0.8 mm thickness and 300 mm width is heated in non-oxidizing conditions to 710 C, passed between box type headers having various slit spacings and header spacings (as indicated below) at a speed of m/min. The difference in temperature caused at the margins (15 mm from the edge) and the center part of the sample and the shape of the strip after it had passed between the headers were studied. The results are shown in Table 1. The temperature of the quenching liquid is 60 C and the hydraulic pressure with in the headers is 0.17 kglcm The opening of each slit is 2 mm, the number of slits being seven on eachside, respectively, and the amount of the jetted What we claim:
  • Apparatus for jetting quenching water on to a moving metal strip at a position where the strip is not immersed in water comprising nozzle plates spaced more than 40 mm apart so that the strip can pass between them, and transverse slits on each of said nozzle plates, the slits being spaced apart less than the spacing of the nozzle plates, and the quenching water being jetted through said slits.
  • Apparatus according to claim 1 comprising box type headers which include baffle plates, each header being provided with a nozzle plate made up from adjacent plate sections, the slits of said nozzle plates corresponding to the strip width.

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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)
US00158968A 1970-07-03 1971-07-01 Method and apparatus for water quenching metal strips Expired - Lifetime US3724826A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP45057977A JPS4917131B1 (de) 1970-07-03 1970-07-03

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US00158968A Expired - Lifetime US3724826A (en) 1970-07-03 1971-07-01 Method and apparatus for water quenching metal strips

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US (1) US3724826A (de)
JP (1) JPS4917131B1 (de)
CA (1) CA944265A (de)
FR (1) FR2100227A5 (de)
GB (1) GB1324980A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4084798A (en) * 1974-09-10 1978-04-18 British Steel Corporation Cooling systems for metal articles
EP1538228A1 (de) * 2003-12-01 2005-06-08 R & D du groupe Cockerill-Sambre Verfahren und Vorrichtung zum Kühlen einer Stahlband
CN101935743A (zh) * 2010-09-10 2011-01-05 北京科技大学 一种中厚板在线淬火倾斜射流冷却器
US20140350746A1 (en) * 2011-12-15 2014-11-27 Posco Method and Apparatus for Controlling the Strip Temperature of the Rapid Cooling Section of a Continuous Annealing Line

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5173911A (en) * 1974-12-24 1976-06-26 Nippon Kokan Kk Kosutoritsupuoteisankajotaidemizuyakiiresuruhoho oyobi sochi
US4417720A (en) * 1979-12-12 1983-11-29 Centre De Recherches Metallurgiques Continuous heat treatment plant for steel sheet
JPS5767134A (en) * 1980-10-09 1982-04-23 Nippon Steel Corp Method and installation for continuous annealing method of cold-rolled steel strip
WO1983000881A1 (en) * 1981-08-28 1983-03-17 Goto, Masayuki Method of cooling metallic strip
FR2552780B1 (fr) * 1983-09-29 1988-03-04 Cegedur Procede de refroidissement module minimisant les deformations des produits plats metallurgiques
JPH0394023A (ja) * 1989-09-05 1991-04-18 Nippon Steel Corp 連続熱処理工程における冷延鋼板冷却方法
BE1011087A3 (fr) * 1997-04-04 1999-04-06 Cockerill Sambre Sa Dispositif de refroidissement de tole dans une ligne continue.
JP4561104B2 (ja) * 2004-01-19 2010-10-13 Ｊｆｅスチール株式会社 冷延鋼板の冷却方法
US9399199B2 (en) * 2013-03-12 2016-07-26 Illinois Tool Works Inc. Turning vane
JP6921196B2 (ja) * 2016-12-16 2021-08-18 ポスコＰｏｓｃｏ 冷却システム

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3186698A (en) * 1963-06-14 1965-06-01 Midland Ross Corp Heat treating apparatus
US3208742A (en) * 1962-02-16 1965-09-28 United States Steel Corp Apparatus for spray quenching
US3410734A (en) * 1965-01-18 1968-11-12 Inland Steel Co Quench system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3208742A (en) * 1962-02-16 1965-09-28 United States Steel Corp Apparatus for spray quenching
US3186698A (en) * 1963-06-14 1965-06-01 Midland Ross Corp Heat treating apparatus
US3410734A (en) * 1965-01-18 1968-11-12 Inland Steel Co Quench system

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4084798A (en) * 1974-09-10 1978-04-18 British Steel Corporation Cooling systems for metal articles
EP1538228A1 (de) * 2003-12-01 2005-06-08 R & D du groupe Cockerill-Sambre Verfahren und Vorrichtung zum Kühlen einer Stahlband
WO2005054524A1 (fr) * 2003-12-01 2005-06-16 Usinor S.A. Procede et dispositif de refroidissement d'une bande d'acier
US20060243357A1 (en) * 2003-12-01 2006-11-02 Usinor S.A. Method and device for cooling a steel strip
CN100465303C (zh) * 2003-12-01 2009-03-04 阿塞洛法国公司 用于对钢带进行冷却的方法和装置
AU2004294469B2 (en) * 2003-12-01 2009-07-16 Arcelor France Method and device for cooling a steel strip
US7645417B2 (en) 2003-12-01 2010-01-12 Arcelor France Method and device for cooling a steel strip
CN101935743A (zh) * 2010-09-10 2011-01-05 北京科技大学 一种中厚板在线淬火倾斜射流冷却器
CN101935743B (zh) * 2010-09-10 2013-04-10 北京科技大学 一种中厚板在线淬火倾斜射流冷却器
US20140350746A1 (en) * 2011-12-15 2014-11-27 Posco Method and Apparatus for Controlling the Strip Temperature of the Rapid Cooling Section of a Continuous Annealing Line
US9783867B2 (en) * 2011-12-15 2017-10-10 Posco Method and apparatus for controlling the strip temperature of the rapid cooling section of a continuous annealing line

Also Published As

Publication number Publication date
GB1324980A (en) 1973-07-25
JPS4917131B1 (de) 1974-04-27
DE2133411A1 (de) 1972-01-13
FR2100227A5 (de) 1972-03-17
CA944265A (en) 1974-03-26
DE2133411B2 (de) 1975-07-03

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