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EP0473561A1 - Verfahren zur Wärmebehandlung eines Stahlprodukts - Google Patents

Verfahren zur Wärmebehandlung eines Stahlprodukts Download PDF

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Publication number
EP0473561A1
EP0473561A1 EP91870119A EP91870119A EP0473561A1 EP 0473561 A1 EP0473561 A1 EP 0473561A1 EP 91870119 A EP91870119 A EP 91870119A EP 91870119 A EP91870119 A EP 91870119A EP 0473561 A1 EP0473561 A1 EP 0473561A1
Authority
EP
European Patent Office
Prior art keywords
product
cooling
temperature
during
air
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.)
Granted
Application number
EP91870119A
Other languages
English (en)
French (fr)
Other versions
EP0473561B1 (de
Inventor
Jean-Michel Dengler
Jean-François Noville
Carlo Panunzi
Stéphan Wilmotte
Albert Zenner
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.)
Centre de Recherches Metallurgiques CRM ASBL
Arcelor Luxembourg SA
Original Assignee
Centre de Recherches Metallurgiques CRM ASBL
Arbed SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
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Application filed by Centre de Recherches Metallurgiques CRM ASBL, Arbed SA filed Critical Centre de Recherches Metallurgiques CRM ASBL
Publication of EP0473561A1 publication Critical patent/EP0473561A1/de
Application granted granted Critical
Publication of EP0473561B1 publication Critical patent/EP0473561B1/de
Anticipated expiration legal-status Critical
Revoked legal-status Critical Current

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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
    • C21D1/02—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 present invention relates to a method of heat treatment of a steel product, preferably carried out immediately after the rolling of this product.
  • the method of the invention is particularly applicable to long products, which generally undergo, after rolling, cooling on a cooler.
  • These include beams, sheet piles, rails, bars and merchant bars of the most varied sections, but also tubes of any shape.
  • a surface quenching treatment is applied to the profile, at its exit from the last stand of the rolling mill, when it is at a temperature above its point Ar3 and self-income.
  • the profile is subjected to accelerated cooling with water, which causes the hardening of a surface layer of the product. This is then deposited on a cooler where it undergoes slow cooling with calm air, firstly comprising self-tempering of the hardened surface layer.
  • Treatments of this kind especially make it possible to modify the microstructure of the steel and thus often dramatically improve the physical properties of the treated product. However, they do not make it possible to reduce the total duration of the cooling cycle significantly compared with simple cooling in air.
  • the object of the present invention is to propose a process for heat treatment of a steel product of the aforementioned type, which can be carried out in a much shorter time than the previous processes and which makes it possible to minimize deformation during cooling.
  • the method of the invention allows the in-line cooling of the parent products leaving the rolling mill, as well as the dressing of these products, also in line, before their cutting to the desired length. It greatly reduces handling of the products and it leads to products having excellent mechanical properties, in particular high strength accompanied by high ductility and resilience.
  • the method of heat treatment of a steel product at the outlet of the rolling mill is characterized in that during a first step the product is subjected to rapid cooling with water from the temperature at the end of rolling up to a surface temperature equal to or lower than the temperature at the start of the martensitic transformation, known as the Ms point, of said steel, with a cooling rate at least equal to the critical quenching speed of said steel, in what, at during a second step, the product is first subjected to a self-tempering phase, during which, thanks to the heat given off by the unhardened part of the product, the hardened surface layer is reheated up to a surface temperature, called self-tempering, between 550 ° C and 650 ° C, and then to a secondary cooling phase, which involves cooling of said product to a surface temperature below 450 ° C, and in that, during a third step, the final cooling of the product is carried out to a temperature below 120 ° C.
  • a self-tempering phase during which, thanks
  • said secondary cooling phase consists of cooling in air to a temperature below 420 ° C.
  • the product is cooled in air to an intermediate temperature between 450 ° C and 420 ° C during said secondary cooling phase, then it is cooled up to a temperature below 80 ° C, during final cooling.
  • This final cooling is preferably carried out with water, in particular to limit the duration of the treatment.
  • the product is first allowed to stay in the air up to a temperature of approximately 550 ° C., it is then cooled at high speed to a surface temperature substantially below 400 ° C., the product is then reheated by dissipation of the internal heat to a temperature between 400 ° C and 420 ° C, cooling in air is carried out, then the final cooling is abruptly carried out to a temperature below 120 ° C.
  • this abrupt final cooling is water cooling.
  • the method of the invention is implemented continuously, with the product leaving the last rolling stand and then traversing the treatment device. After the final cooling according to one or the other embodiment, the product is drawn up continuously, then it is cut to the desired length.
  • the reference numeral 1 in FIG. 1 designates the rolled steel product, in this case a profile, which moves in the direction of arrow 2.
  • This product circulates continuously in a series of devices where it is subjected to the stages of successive cooling, corresponding to the diagrams in Figures 2 and 3.
  • the product 1 leaves the last stand of the rolling mill, symbolized by a pair of cylinders 3, and immediately enters a first cooling device 4.
  • This first device known per se, consists of a tube of appropriate section, filled with circulating water.
  • Product 1 undergoes abrupt surface cooling there, from the end of rolling temperature to a surface temperature below the point Ms of the steel in question; during this first cooling (of duration t1), a layer of martensite is formed on the surface of product 1.
  • this surface layer of martensite depends on the speed and intensity of the cooling, that is to say in fact on the duration t1 and on the surface temperature of the product to be the end of cooling.
  • the product 1 is transferred to a cooler 5, where it is subjected to in-line cooling according to one or the other embodiment of the method of the present invention.
  • the product undergoes a first phase, self-income phase, during which there is an equalization of the temperature between the core and the surface of the product; the core cools and the surface heats up to a temperature between 550 ° C and 650 ° C, which causes self-tempering of the surface layer of martensite.
  • the self-income phase has a duration t2. The differences between the forms of execution relate to the operations which follow the self-income phase.
  • FIG. 2 represents the temporal evolution of the surface temperature of the product when the secondary phase of the second stage of the process consists only of air cooling.
  • this secondary phase consists of air cooling of the product to a temperature below 450 ° C, and preferably below 420 ° C.
  • the duration t3 of this cooling in still air naturally depends on the type of product, in particular on its thickness. It is essential to allow the product to cool in air to a temperature below 450 ° C, and preferably below 420 ° C, to guarantee good resilience of the final product. If the final cooling, that is to say the third stage of the process, is applied, from too high a temperature, the residual austenite which is not yet transformed and enriched in carbon can transform into martensite and give rise to a fragile structure.
  • This final cooling, of duration t4 is carried out with water to limit the duration of the treatment; it should no longer have a metallurgical effect.
  • the diagram in FIG. 3 represents the temporal evolution of the surface temperature of the product, when the second phase of the second stage of the process successively comprises air cooling (t31), intense cooling (t32), an auto -heating (t33) and air cooling (t34).
  • An intense cooling (t32) is then carried out, generally with circulating water, from this temperature of approximately 550 ° C. to a surface temperature of 300 ° C.
  • air cooling (t34) is carried out from 400 ° C to 300 ° C during which performs the ferrite overaging reaction; then the final cooling (t4) constituting the third step of the process is carried out.
  • This final cooling is carried out with water up to the temperature of 80 ° C., temperature at which the product can be handled without being altered.
  • the product 1 can still be dressed in a dressing device 7, then a shear 8 cuts it into sections of desired length, which are evacuated by an outlet conveyor 9.
  • the dressing must be carried out at a temperature below 120 ° C and preferably below 80 ° C to avoid any subsequent deformation.
  • the following two tables indicate typical cooling times for the different stages of the process of the invention, in the case of profiles of different thicknesses.
  • the thicknesses e of the profiles are expressed in millimeters (mm) and the times (t i ) are expressed in seconds (s).
  • Table 1 corresponds to the first embodiment described above and shown schematically in Figure 2.
  • the duration of self-income (t3) increases rapidly with the thickness of the profile, and risks becoming prohibitive for products of very thick (> 40 mm); it is therefore interesting to insert intense cooling in the second phase of the second stage of the process, as shown in Figure 3.
  • Table 2 illustrates this embodiment. We note that it brings in all cases a significant time saving (about 20 minutes for products of 125 mm thickness). This time saving does not harm the quality of the products, because they have good straightness, high resistance, as well as excellent resilience at any point in their section.
  • the method of the invention makes it possible to carry out the entire treatment, including dressing, on the parent products, that is to say as they come out of the rolling mill. We thus significantly reduce the number of manipulations required and therefore the risk of the appearance of faults linked to these manipulations. Finally, only one short cooler is used since the stay in the air is short, which limits on the one hand the risk of confusion between the products and on the other hand the degree of oxidation of the product surface.

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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)
  • Heat Treatment Of Articles (AREA)
  • Heat Treatment Of Steel (AREA)
  • Control Of Heat Treatment Processes (AREA)
  • Metal Rolling (AREA)
EP91870119A 1990-08-14 1991-08-06 Verfahren zur Wärmebehandlung eines Stahlprodukts Revoked EP0473561B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BE9000787A BE1004526A6 (fr) 1990-08-14 1990-08-14 Procede de traitement thermique d'un produit en acier.
BE9000787 1990-08-14

Publications (2)

Publication Number Publication Date
EP0473561A1 true EP0473561A1 (de) 1992-03-04
EP0473561B1 EP0473561B1 (de) 1996-02-07

Family

ID=3884898

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91870119A Revoked EP0473561B1 (de) 1990-08-14 1991-08-06 Verfahren zur Wärmebehandlung eines Stahlprodukts

Country Status (5)

Country Link
EP (1) EP0473561B1 (de)
JP (1) JPH04232206A (de)
AT (1) ATE133996T1 (de)
BE (1) BE1004526A6 (de)
DE (1) DE69116958D1 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0882804A1 (de) * 1997-06-05 1998-12-09 DANIELI & C. OFFICINE MECCANICHE S.p.A. Verfahren und Vorrichtung zum Wärmebehandeln von Walsprodukten
US6264767B1 (en) 1995-06-07 2001-07-24 Ipsco Enterprises Inc. Method of producing martensite-or bainite-rich steel using steckel mill and controlled cooling
CN108285950A (zh) * 2018-02-11 2018-07-17 中冶陕压重工设备有限公司 一种控制森吉米尔轧机工作辊淬火变形的热处理方法
CZ307645B6 (cs) * 2017-02-15 2019-01-30 Západočeská Univerzita V Plzni Způsob výroby součástí z ocelí

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100505730B1 (ko) * 2002-12-13 2005-08-03 두산중공업 주식회사 고강도와 고인성을 갖는 롤쉘의 열처리 방법
JP4817898B2 (ja) * 2006-03-14 2011-11-16 トピー工業株式会社 熱処理装置および熱処理方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE834059A (fr) * 1975-09-30 1976-01-16 Procede de traitement des produits en acier lamines
GB1471855A (en) * 1975-01-29 1977-04-27 Centre Rech Metallurgique Producing rolled steel products
BE854647A (fr) * 1977-05-13 1977-09-01 Centre Rech Metallurgique Procede de production de profiles en acier de qualite amelioree
FR2405998A1 (fr) * 1977-10-14 1979-05-11 Centre Rech Metallurgique Perfectionnements aux procedes de traitement de profiles tubulaires en acier
EP0124501A1 (de) * 1983-03-31 1984-11-07 CENTRE DE RECHERCHES METALLURGIQUES CENTRUM VOOR RESEARCH IN DE METALLURGIE Association sans but lucratif Verfahren zur Qualitätsverbesserung von Stahlprofilen

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1471855A (en) * 1975-01-29 1977-04-27 Centre Rech Metallurgique Producing rolled steel products
BE834059A (fr) * 1975-09-30 1976-01-16 Procede de traitement des produits en acier lamines
BE854647A (fr) * 1977-05-13 1977-09-01 Centre Rech Metallurgique Procede de production de profiles en acier de qualite amelioree
FR2405998A1 (fr) * 1977-10-14 1979-05-11 Centre Rech Metallurgique Perfectionnements aux procedes de traitement de profiles tubulaires en acier
EP0124501A1 (de) * 1983-03-31 1984-11-07 CENTRE DE RECHERCHES METALLURGIQUES CENTRUM VOOR RESEARCH IN DE METALLURGIE Association sans but lucratif Verfahren zur Qualitätsverbesserung von Stahlprofilen

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6264767B1 (en) 1995-06-07 2001-07-24 Ipsco Enterprises Inc. Method of producing martensite-or bainite-rich steel using steckel mill and controlled cooling
EP0882804A1 (de) * 1997-06-05 1998-12-09 DANIELI & C. OFFICINE MECCANICHE S.p.A. Verfahren und Vorrichtung zum Wärmebehandeln von Walsprodukten
US6096146A (en) * 1997-06-05 2000-08-01 Danieli & C. Officine Meccanichi Spa Method for heat treating rolled stock and device to achieve the method
CZ307645B6 (cs) * 2017-02-15 2019-01-30 Západočeská Univerzita V Plzni Způsob výroby součástí z ocelí
CN108285950A (zh) * 2018-02-11 2018-07-17 中冶陕压重工设备有限公司 一种控制森吉米尔轧机工作辊淬火变形的热处理方法

Also Published As

Publication number Publication date
EP0473561B1 (de) 1996-02-07
BE1004526A6 (fr) 1992-12-08
JPH04232206A (ja) 1992-08-20
ATE133996T1 (de) 1996-02-15
DE69116958D1 (de) 1996-03-21

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