WO1999019522A1 - Procede pour eviter des tapures de trempe a la surface interieure d'un corps creux cylindrique - Google Patents

Procede pour eviter des tapures de trempe a la surface interieure d'un corps creux cylindrique Download PDF

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Publication number
WO1999019522A1
WO1999019522A1 PCT/DE1998/002696 DE9802696W WO9919522A1 WO 1999019522 A1 WO1999019522 A1 WO 1999019522A1 DE 9802696 W DE9802696 W DE 9802696W WO 9919522 A1 WO9919522 A1 WO 9919522A1
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WO
WIPO (PCT)
Prior art keywords
hollow body
quenching
water
steel
quenching phase
Prior art date
Application number
PCT/DE1998/002696
Other languages
German (de)
English (en)
Inventor
Gerd Kloster
Fritz Kegel
Christoph Prasser
Ingo Von Hagen
Peter Christian Zinkler
Original Assignee
Mannesmann Ag
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
Application filed by Mannesmann Ag filed Critical Mannesmann Ag
Publication of WO1999019522A1 publication Critical patent/WO1999019522A1/fr

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Classifications

    • 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
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C21D9/085—Cooling or quenching
    • 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
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C21D9/14—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes wear-resistant or pressure-resistant pipes

Definitions

  • the invention relates to a method for avoiding hardness cracks on the inner surface of a cylindrical hollow body made of steel, which initially on
  • Austenitizing temperature is heated and then quenched with water and the hollow body rotates about its longitudinal axis during quenching.
  • Austenitizing temperature heated hollow bodies in a coolant bath e.g. is cooled in a water bath by rotating immersion in such a way that its longitudinal axis is aligned parallel to the bath level of the coolant bath, only a part of its surface is immersed in the coolant bath and is rotated several times about its longitudinal axis during cooling.
  • EP 0 345 205 B1 discloses a similar method for hardening cylindrical hollow bodies made of steel as part of a tempering treatment, in which the hollow body is rotated about its longitudinal axis in a water bath during quenching. To intensify the cooling effect of the water bath in the first
  • EP 0 625 215 B1 discloses a system for quenching steel pipes by rotating immersion, in which the steel pipe is simultaneously cooled with water on the inside and outside surface and is continuously rotated about the longitudinal axis. To quench the inner surface of the pipe, a water injection nozzle is provided, which is brought into a corresponding injection position relative to the steel pipe above the water bath and is lowered into the water bath together with the steel pipe and the rotating device while maintaining this relative position to the steel pipe. The internal cooling is switched on when immersed.
  • Reject rates in the production of tempered steel pipes from such materials are used in the context of the tempering treatment.
  • Oil baths are used to deter austenitizing temperatures in order to achieve a slower cooling that is more favorable for the avoidance of hardening cracks.
  • the object of the present invention is to further develop a method of the generic type in such a way that, while maintaining the coolant, the formation of hard cracks is avoided as part of the hardening treatment of cylindrical hollow bodies, even if steel materials are used for these hollow bodies, which form hardness cracks tend to be used in the commonly used processes. Furthermore, a drill pipe with upset pipe ends should be proposed, which is hardened and has no hard cracks.
  • This object is achieved in a generic method in that at least during a first quenching phase, which is immediately related to the
  • Austenitization of the hollow body to be treated then, this hollow body is only exposed to water on its inner surface, the first quenching phase being extended at least until the martensite start temperature on the inner surface has fallen below.
  • This method of the present invention can be used with particular advantage in the case of hollow bodies, which are made of steel (preferably low-alloy steel), the C content of which is at least 0.3% by weight, in particular at least 0.4% by weight. It is useful to use seamless steel tubes in the hot-rolled state as hollow bodies. Of course, other hollow bodies such as welded steel pipes can also be treated using this method. It is only important that the water used for cooling can reach the inner surface of the hollow body to a sufficient extent.
  • the water is expediently injected into the hollow body in the first quenching phase with an excess pressure of at least 4 bar, preferably at least 6 bar.
  • the practically sensible pressure range can be limited to approx. 10 bar. However, higher pressures are also readily applicable.
  • the duration of the cooling of the inner surface should be at least 10 seconds. For many applications, a duration of approx. 15 - 20 seconds is recommended for internal cooling.
  • the entire quenching treatment can be carried out by exposure to water on the
  • Interior surface can be made.
  • a second quenching phase is provided on the inner surface after the martensite start temperature has been reached, in which the respective hollow body is also quenched with water on its outer surface.
  • the hollow body is expediently immersed in a water bath, the hollow body preferably also rotating about its longitudinal axis during the second quenching phase.
  • the method according to the invention is used with very particular advantage for the hardening of drill pipes with upset pipe ends.
  • the cracking in conventionally quenched hollow bodies normally started when the structure was completely converted from austenite to the hardening structure.
  • the hardening structure consists of martensite. Accordingly, the cracking begins at temperatures which are below the temperature at which a 100% conversion to martensite has taken place. Depending on the material, this temperature can be read from the corresponding ZTU diagram. For example, for a 40CrMo4 steel, this temperature is around 100 ° C depending on the duration of the cooling. It It was found that the starting point for the crack formation is mainly in small surface imperfections that act as notches. In the notch base there are stress concentrations that cause the crack to start.
  • Steel pipes that were seamlessly produced by hot rolling preferably show hardness cracks on the inner surface.
  • the inner surfaces of such pipes are regularly significantly more vulnerable than the outer surfaces due to the shaping process used.
  • the crack starters can therefore be found on the inside.
  • cooling usually takes place from the outside in. This is also the case with the methods mentioned at the beginning.
  • Martensite formation on the inside of the pipe is delayed.
  • the inside diameter is smaller relative to the outside diameter than at the beginning of the quenching process. Therefore, considerable tensile stresses remain on the inside of the pipe, which, depending on the material, can lead to undesirable crack formation.
  • This active mechanism is specifically reversed by the present invention by first quenching the inside of the respective hollow body, so that there are corresponding plastic deformations in the area of the outer surface comes and compressive stresses arise on the inside.
  • this eliminates the danger that surface imperfections on the inside become crack starters.
  • the tensile stresses in the outer surface are significantly less dangerous since, due to the peculiarities of the hot rolling processes, significantly fewer notches are normally produced on the outside.
  • a hot-rolled steel pipe with a diameter of 152.4 mm and a wall thickness of 22.2 mm was hot-rolled in an oven and hot-rolled at about 870 ° C.
  • the material of the steel tube had the following composition:
  • the austenitized steel pipe was then fed to a so-called rotary immersion system for deterrence.
  • Water was used as the coolant in the rotary immersion system.
  • a first quenching phase which lasted approximately 16 seconds, the inside of the steel tube was quenched to a temperature of approximately 300 ° C. with water that was injected at a pressure of approximately 6 bar. In the area of the inner surface, the structure largely converted to martensite.
  • the pipe was rotated around its longitudinal axis at a speed of 60 min "1.
  • the horizontal pipe was continuously immersed in a water bath and cooled to a temperature (compensation temperature) of 25 ° C.
  • the steel pipe treated in this way showed an almost exclusively martensitic structure over the entire wall thickness. Neither the inside surface nor the outside surface of the tube had hard cracks.

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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 Articles (AREA)

Abstract

L'invention concerne un procédé destiné à éviter des tapures de trempe à la surface intérieure d'un corps creux cylindrique en acier à teneur en carbone d'au moins 0,3 % en poids, qui est tout d'abord chauffé à une température d'austénisation puis trempé à l'eau, le corps creux étant, en cours de trempe, entraîné en rotation autour de son axe longitudinal. L'invention est caractérisée en ce qu'au moins pendant une première phase de trempe qui se rattache directement à l'austénisation, le corps creux n'est soumis à l'action de l'eau que sur sa surface intérieure, et en ce que la première phase de trempe est prolongée au moins jusqu'à ce qu'on passe au-dessous de la température martensitique de départ sur la surface intérieure.
PCT/DE1998/002696 1997-10-08 1998-09-04 Procede pour eviter des tapures de trempe a la surface interieure d'un corps creux cylindrique WO1999019522A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19745605 1997-10-08
DE19745605.7 1997-10-08

Publications (1)

Publication Number Publication Date
WO1999019522A1 true WO1999019522A1 (fr) 1999-04-22

Family

ID=7845641

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE1998/002696 WO1999019522A1 (fr) 1997-10-08 1998-09-04 Procede pour eviter des tapures de trempe a la surface interieure d'un corps creux cylindrique

Country Status (1)

Country Link
WO (1) WO1999019522A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2218958A (en) * 1939-03-03 1940-10-22 Harrisburg Steel Corp Apparatus for the hardening of tubular steel articles
US4032369A (en) * 1976-02-02 1977-06-28 The Timken Company Method for quenching ferrous tubing to achieve full hardening without quench cracking
DE2703852A1 (de) * 1977-01-31 1978-08-03 Nippon Kokan Kk Verfahren und vorrichtung zum kuehlen der innenflaeche von metallrohren
DE3004872A1 (de) * 1979-03-15 1980-09-18 Usui Kokusai Sangyo Kk Rohr fuer hochdruckfluessigkeit und verfahren zu dessen herstellung
EP0356417A1 (fr) * 1988-08-04 1990-02-28 SCHOELLER-BLECKMANN Gesellschaft m.b.H. Procédé pour la fabrication de pièces tubulaires résistant à la corrosion sous tension, notamment de masses-tiges non magnétisables en acier austénitique et pièces ainsi obtenues
JPH09104925A (ja) * 1995-10-09 1997-04-22 Sumitomo Metal Ind Ltd 中・高炭素含有鋼管の焼入れ方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2218958A (en) * 1939-03-03 1940-10-22 Harrisburg Steel Corp Apparatus for the hardening of tubular steel articles
US4032369A (en) * 1976-02-02 1977-06-28 The Timken Company Method for quenching ferrous tubing to achieve full hardening without quench cracking
DE2703852A1 (de) * 1977-01-31 1978-08-03 Nippon Kokan Kk Verfahren und vorrichtung zum kuehlen der innenflaeche von metallrohren
DE3004872A1 (de) * 1979-03-15 1980-09-18 Usui Kokusai Sangyo Kk Rohr fuer hochdruckfluessigkeit und verfahren zu dessen herstellung
EP0356417A1 (fr) * 1988-08-04 1990-02-28 SCHOELLER-BLECKMANN Gesellschaft m.b.H. Procédé pour la fabrication de pièces tubulaires résistant à la corrosion sous tension, notamment de masses-tiges non magnétisables en acier austénitique et pièces ainsi obtenues
JPH09104925A (ja) * 1995-10-09 1997-04-22 Sumitomo Metal Ind Ltd 中・高炭素含有鋼管の焼入れ方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 097, no. 008 29 August 1997 (1997-08-29) *

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