EP0090682B1 - Wärmebehandlungsverfahren und Vorrichtung zum Herstellen gebrauchsfertiger Stangen aus legierten Stählen - Google Patents

Wärmebehandlungsverfahren und Vorrichtung zum Herstellen gebrauchsfertiger Stangen aus legierten Stählen Download PDF

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Publication number
EP0090682B1
EP0090682B1 EP83400378A EP83400378A EP0090682B1 EP 0090682 B1 EP0090682 B1 EP 0090682B1 EP 83400378 A EP83400378 A EP 83400378A EP 83400378 A EP83400378 A EP 83400378A EP 0090682 B1 EP0090682 B1 EP 0090682B1
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EP
European Patent Office
Prior art keywords
cooling
rod
forced cooling
cooler
water
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
EP83400378A
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English (en)
French (fr)
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EP0090682A3 (en
EP0090682A2 (de
Inventor
Yves Desalos
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Institut de Recherches de la Siderurgie Francaise IRSID
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Institut de Recherches de la Siderurgie Francaise IRSID
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Priority to AT83400378T priority Critical patent/ATE62278T1/de
Publication of EP0090682A2 publication Critical patent/EP0090682A2/de
Publication of EP0090682A3 publication Critical patent/EP0090682A3/fr
Application granted granted Critical
Publication of EP0090682B1 publication Critical patent/EP0090682B1/de
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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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62—Quenching devices
    • 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
    • C21D1/02—Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation
    • 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
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching

Definitions

  • the invention relates to the field of heat treatment of metal bars at the end of rolling and more particularly relates to the direct production of quenching structures, preferably martensite, and optionally bainite, in the useful part of steel, intended in particular for mechanical construction.
  • the steel industry currently delivers alloy steels with improved machinability which exhibit, with the quenched and tempered effect, machinability comparable to that of conventional steels of the same composition but in the annealed state. Consequently, the possibility of machining certain parts from bars having the final characteristics of use is of considerable economic interest, in particular due to the elimination of annealing for machining on a blank, of the quenching and tempering treatment for the user, or resuming machining by rectification.
  • Direct quenching in a swimming pool of water would, for its part, be insufficiently rapid for the largest diameters and would risk leading to bar bending (due to the asymmetries of treatment), or to curls (due to the setting in tension of the fragile peripheral layer of martensite during the swelling linked to the subsequent transformation of the heart).
  • Document DD-119270 describes a quenching treatment interrupted in at least two steps immediately following rolling.
  • a steel bar first undergoes a very rapid quenching bringing its peripheral part to a temperature lower than the martensitic transformation temperature of the steel considered. Then the quenching is interrupted so as to allow the temperatures of the core and the periphery of the product to equalize. Finally the bar is subjected to a second less energetic quenching at the end of which the core of the bar is transformed into martensite.
  • the whole treatment lasts about 1.5 s and is only intended for products with a very small section, for example with a diameter of 10 mm.
  • the object of the invention is to obtain, without bending or taping, quenching structures in the section of ready-to-use rolled alloy steel bars having large diameters.
  • the invention also relates to an installation for implementing the method successively comprising, in the direction of travel of the product, means enabling a forced cooling of the bars in the parade according to step a) ensuring an average heat exchange coefficient greater than 5.103W / m2. ° C, and a chiller with movable beams ensuring a regular translation "with crawl steps” and a slow rotation on itself of the bar, said cooler being equipped with forced cooling means.
  • the cooling means according to step a) consist of at least one water box where the bar is wrapped in a sheet of water flowing collinearly with the bar.
  • the means for the more moderate forced cooling of the stage can be constituted by oscillating ramps with water spraying, or a pool of water or oil.
  • FIG. 1 shows, by way of example only intended to better understand the technical field of the invention, a diagram, of current use in thermal treatments, which represents on a temperature-time graph , the different micrographic constituents resulting, according to the cooling laws considered, from the transformation ⁇ ⁇ ⁇ of the metastable austenite identified 1.
  • rapid cooling laws lead to the instantaneous formation of martensite 2 as soon as the temperature of the metal drops below the temperature Ms of the steel (310 ° C. in the example chosen).
  • very slow cooling laws lead to the formation of ferrite 3 and perlite 4 at temperatures above 600 ° C.
  • intermediate cooling laws lead to the formation of bainite 5 and of a volume fraction which is all the more significant in martensite as the end of cooling is accelerated.
  • the operating modes of the above-described installation depend, at each cooling step, on the bar diameter considered, on the exit speed of the rolling mill, on the hardenability of the steel grade considered and on the desired structures at the heart of the bars.
  • the necessary cooling times have been seen depending on the diameter of the bars for a heat exchange coefficient of the quenching device of the order of 104 w / m2. ° C. Knowing the exit speeds in rolling and the temperatures at the end of rolling, we can deduce the necessary quenching lengths.
  • a limiting case is that where the speed of movement of the bar and the hardenability of the grade considered allows the following evolution of the average temperature of the section: end of rolling around 900 ° C., crossing of a first box with blade d water from 900 to 600 ° C, natural cooling in 1 to 2 minutes, passing through a second box with a blade of water from 600 to 400 - 300 ° C before final tempering.
  • the bar 20 comes out of the last stand of the rolling mill 21 to enter one or two boxes 22 with circulation of a water blade of the type of those described in patent application EP-A-0020246.
  • This bar is extracted at regular speed from the water boxes using the extractors 23, then slowed down to a stop on a line of braking rollers 24.
  • a tilting device 25 allows the bar to be placed on a cooler 29 with movable beams performing a movement in "no pilgrim" to ensure the bar a slow translation and rotation on itself.
  • the cooler 29 has three zones, marked 26, 27 and 28a. Zone 26 corresponds to the natural cooling of step b) according to the invention.
  • Zone 27 is a natural cooling of evacuation of the bars after the forced cooling phase ensured in zone 28a, but we can possibly start the final income from this zone 27.
  • zone 28a corresponds to forced cooling of the step c) according to the invention. This cooling is, in this example, ensured by water spraying ramps parallel to the bars and driven in a longitudinal movement back and forth sufficient for the treatment to be uniform along the bars.
  • FIG. 3 corresponds exactly to the description of FIG. 2, with the exception of the forced cooling of step c) which is carried out at 28b by progressive immersion in a pool of water or oil.
  • An advantageous device of inclined planes not shown allows the progressive introduction and extraction of the bars.
  • Figure 5 corresponds to the same representations as Figure 4, but with a 3rd cooling step according to the invention (step c) characterized by a heat exchange coefficient of 103 W / m2. ° C.
  • the martensitic transformation conditions were carried out substantially from the core up to 0 ⁇ 15 ⁇ 4 mm from the skin, the annular peripheral layer consisting of self-returning martensite.
  • a subsequent tempering of one hour at 500 ° C. on this bar made it possible to obtain a roughly uniform mechanical resistance throughout the section and close to 1000 N / mm2.
  • the Charpy V resilience measured at the core of the bar was only 40 J / cm2 at room temperature.
  • a step c) corresponding to quenching up to 100 ° C characterized by an average exchange coefficient of the order of 103 w / m2. ° C we follow, at the heart of a 0 ⁇ 60 mm bar, the law 41 of Figure 5. The transformation is then entirely martensitic over the entire section, (a final oil quenching, significantly less effective, would have still leads to 70% martensite at heart). For bars of 100 and 150 mm in diameter, almost three-quarters of the core transformation takes place below 400 ° C with almost 50% martensite. In all cases, an hour's income at 600 ° C made it possible to obtain a resistance of the order of 1000 N / mm2 and a Charpy V resilience to the ambient greater than 60 J / cm2.
  • the process according to the invention also lends itself well to the recovery of rolling operations completed at low temperature (around 850 ° C.), which make it possible to keep a hardened austenite which is not recrystallized at the time of the transformation ⁇ ⁇ ⁇ .
  • the inheritance of the crystalline defects of the hardened austenite will be all the more interesting that one will pass quickly to temperatures where the restoration of austenite is difficult, then to final structures of hardening.

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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 Treatment Of Articles (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
  • Heat Treatment Of Steel (AREA)
  • Coating With Molten Metal (AREA)

Claims (9)

  1. Warmbehandlungsverfahren für verwendungsbereite legierte Stahlbarren eines Durchmessers von 50 bis 150 mm, insbesondere für mechanische Konstruktionen, dadurch gekennzeichnet, dass es in einem gestuften Abschrecken aus der Walzhitze besteht, das die folgenden aufeinanderfolgenden Schritte aufweist:
    a) gerade nach dem Walzen unterwirft man den vorüberziehenden Barren einer starken zwangsweisen Abkühlung mit einem Wärmetauschkoeffizienten der Grössenordnung von 10⁴W/m².°C derart, dass die Durchschnittstemperatur des Querschnittes des Barren rasch bis etwa 600-550 °C abgesenkt und eine oberflächliche Martensitschicht unter Vermeidung einer Bildung von Ferrit und Perlit im Kern gebildet wird;
    b) anschliessend verursacht man ein Selbstanlassen der oberflächlichen Martensitschicht, indem man den Barren auf natürliche Weise an der Luft auskühlen lässt, bis man im wesentlichen auf eine neuerliche thermische Homogenisierung über den Querschnitt gegen 550°C gelangt, wobei man die signifikante Bildung von Perlit oder Bainit im Kern vermeidet;
    c) sodann unterwirft man den Barren neuerlich einer zwangsweisen Abkühlung geringerer Stärke als jener des Schrittes a), damit die Kerntemperatur unter etwa 300 °C innerhalb einer mit der Kinetik der hauptsächlich martensitischen Umwandlung und der bainitischen der bearbeiteten Stahlsorte vereinbaren Zeit fällt.
  2. Anlage zur Durchführung des Verfahrens nach Anspruch 1, dadurch gekennzeichnet, dass sie im Sinne des Durchlaufes des Produktes nacheinander folgendes aufweist:
    - Einrichtungen, die ein zwangsweises Abkühlen der vorüberziehenden Barren gemäss Schritt a) gewährleisten und einen durchschnittlichen Wärmetauschko effizienten oberhalb 5.10³W/m².°C sichern;
    - ein Hubbalkenkühlbett, das eine regelmässige Pilgerschrittbewegung und eine langsame Umdrehung des Barrens um sich selbst sichert, welches Kühlbett mit Zwangskühleinrichtungen versehen ist.
  3. Anlage nach Anspruch 2, dadurch gekennzeichnet, dass die Kühleinrichtungen für das Produkt gemäss Stufe a) von wenigstens einem Wasserkasten (22) gebildet sind, wo der Barren von einer kolinear mit dem Barren zirkulierenden Wasserschicht eingehüllt wird.
  4. Anlage nach Anspruch 3, dadurch gekennzeichnet, dass die Kühleinrichtungen für das Produkt gemäss Stufe a) von einer Wasserzerstäubungseinrichtung gebildet sind.
  5. Anlage nach Anspruch 2, dadurch gekennzeichnet, dass die am Kühlbett vorgesehenen Zwangskühleinrichtungen von Wasserzerstäubungsrohren gebildet sind.
  6. Anlage nach Anspruch 5, dadurch gekennzeichnet, dass die Rohre zu einer parallel zur Achse des zu kühlenden Barrens verlaufenden hin- und hergehenden Bewegung angetrieben sind.
  7. Anlage nach Anspruch 2, dadurch gekennzeichnet, dass die am Kühlbett vorgesehenen Zwangskühleinrichtungen von einem Wasser- oder Ölbad gebildet sind.
  8. Anlage nach Anspruch 7, dadurch gekennzeichnet, dass das Bad zwei geneigte Ebenen zum jeweiligen Sichern des zunehmenden Eintauchens und Herausführens der zu kühlenden Barren aufweist.
  9. Anlage nach einem der Ansprüche 2 bis 8, dadurch gekennzeichnet, dass sie eine nach dem Kühlbad angeordnete thermische Anlaßstation für die Barren aufweist.
EP83400378A 1982-03-03 1983-02-24 Wärmebehandlungsverfahren und Vorrichtung zum Herstellen gebrauchsfertiger Stangen aus legierten Stählen Expired - Lifetime EP0090682B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT83400378T ATE62278T1 (de) 1982-03-03 1983-02-24 Waermebehandlungsverfahren und vorrichtung zum herstellen gebrauchsfertiger stangen aus legierten staehlen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8203659A FR2522688B1 (fr) 1982-03-03 1982-03-03 Procede et installation de traitement thermique de barres en acier allie pretes a l'emploi, notamment pour la construction mecanique
FR8203659 1982-03-03

Publications (3)

Publication Number Publication Date
EP0090682A2 EP0090682A2 (de) 1983-10-05
EP0090682A3 EP0090682A3 (en) 1987-09-02
EP0090682B1 true EP0090682B1 (de) 1991-04-03

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EP83400378A Expired - Lifetime EP0090682B1 (de) 1982-03-03 1983-02-24 Wärmebehandlungsverfahren und Vorrichtung zum Herstellen gebrauchsfertiger Stangen aus legierten Stählen

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EP (1) EP0090682B1 (de)
JP (1) JPS58189328A (de)
AT (1) ATE62278T1 (de)
BE (1) BE896021A (de)
DE (1) DE3382237D1 (de)
FR (1) FR2522688B1 (de)
LU (1) LU84666A1 (de)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3927276A1 (de) * 1989-08-18 1991-02-21 Schloemann Siemag Ag Verfahren zum haerten von stahl mit hilfe fluessiger kuehlmedien
CN105400945B (zh) * 2015-12-17 2018-02-16 北京科技大学 一种大直径斜轧球磨钢球热处理系统
CN105385831B (zh) * 2015-12-17 2018-02-16 北京科技大学 一种斜轧球磨钢球余热利用热处理装置

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD84615A (de) *
DE925527C (de) * 1941-07-30 1955-03-24 Oberhuetten Vereinigte Obersch Verfahren und Vorrichtung zum Haerten und Vergueten von gewalzten Gegenstaenden
DD112144A1 (de) * 1974-06-12 1975-03-20
DD119270B1 (de) * 1975-04-02 1987-10-14 Florin Stahl Walzwerk Verfahren zur herstellung von walzstahlerzeugnissen mit entfestigter randzone und hochfestem kern
FR2457724A1 (fr) * 1979-06-01 1980-12-26 Siderurgie Fse Inst Rech Dispositif de refroidissement de produits longs lamines en defilement
FR2488279A1 (fr) * 1980-08-08 1982-02-12 Siderurgie Fse Inst Rech Traitement par refroidissement accelere de barres en acier dans la chaude de laminage

Also Published As

Publication number Publication date
FR2522688B1 (fr) 1990-09-14
BE896021A (fr) 1983-06-16
EP0090682A3 (en) 1987-09-02
JPS58189328A (ja) 1983-11-05
ATE62278T1 (de) 1991-04-15
DE3382237D1 (de) 1991-05-08
LU84666A1 (fr) 1983-09-08
FR2522688A1 (fr) 1983-09-09
JPH0335363B2 (de) 1991-05-28
EP0090682A2 (de) 1983-10-05

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