WO2014173494A1 - Procédé de réglage du point de rosée d'un four de traitement thermique - Google Patents

Procédé de réglage du point de rosée d'un four de traitement thermique Download PDF

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Publication number
WO2014173494A1
WO2014173494A1 PCT/EP2014/000892 EP2014000892W WO2014173494A1 WO 2014173494 A1 WO2014173494 A1 WO 2014173494A1 EP 2014000892 W EP2014000892 W EP 2014000892W WO 2014173494 A1 WO2014173494 A1 WO 2014173494A1
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WO
WIPO (PCT)
Prior art keywords
heat treatment
treatment furnace
point temperature
nitrogen
dew point
Prior art date
Application number
PCT/EP2014/000892
Other languages
German (de)
English (en)
Inventor
Matthias Bors
Original Assignee
Linde Aktiengesellschaft
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 Linde Aktiengesellschaft filed Critical Linde Aktiengesellschaft
Publication of WO2014173494A1 publication Critical patent/WO2014173494A1/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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/76—Adjusting the composition of the atmosphere
    • 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
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • 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
    • C21D11/00—Process control or regulation for heat treatments

Definitions

  • the invention relates to a method for controlling a dew point temperature of a heat treatment furnace for a heat treatment of workpieces, wherein the heat treatment furnace is operated with at least one fuel gas-oxygen burner, and a heat treatment furnace for a heat treatment of
  • certain material properties can be generated by exposing the workpieces to certain temperatures or temperature gradients.
  • Methods of heat treatment for example, the annealing, curing or tempering, with which the structure of a metal, so the arrangement of the crystallites contained, can be selectively influenced. Properties such as hardness, toughness, cold workability or microstructure homogeneity of the workpieces can be planned in this way.
  • the components of UHS steel can be austenitized in heat treatment plants and then molded in a press and simultaneously cooled and hardened. Components with a strength> 1450MPa can be manufactured in this way.
  • the object which now arises to those skilled in the art is to provide a way to prevent the formation of hydrogen in heat treatment furnaces and associated damage to workpieces manufactured in the heat treatment furnaces.
  • the amount of nitrogen supplied is determined based on an actual value of the dew point temperature determined in the heat treatment furnace.
  • the actual value of the dew point temperature is controlled by this specific amount of nitrogen supplied to a desired value.
  • the target value of the dew point temperature is expediently chosen such that no or hardly formation of hydrogen can occur.
  • the invention is suitable for all types of heat treatment furnaces or heat treatment systems.
  • the heat treatment furnace can be designed as a rotary drum furnace, a roller hearth furnace or a chamber furnace.
  • the invention is based on the recognition that an atmosphere of a
  • Heat treatment furnace made of nitrogen and air has particular advantages.
  • Atmospheric composition has significant advantages over a pure nitrogen atmosphere. True, a pure nitrogen atmosphere in one
  • a nitrogen atmosphere favors the formation of a fine silicon nitride layer on the fabricated workpieces, which in turn increased to an increased Wear of tools that are used to process the finished workpieces (for example, during the forming of heat-treated sheets).
  • the use according to the invention of a nitrogen-air atmosphere for regulating the dew point temperature of the heat treatment furnace prevents or at least reduces the formation of hydrogen in the heat treatment furnace and thus damage to finished workpieces.
  • the reduced nitrogen content in the atmosphere of the heat treatment furnace reduces the reaction of nitrogen with the workpieces compared to the pure nitrogen atmosphere, thereby forming a silicon nitride layer on the workpieces and thus the associated increased wear of tools for machining the workpieces prevented or at least reduced.
  • Dew point temperature changed. Thus, eventually the dew point temperature is changed.
  • Heat treatment furnace can be adjusted accordingly flexible and reliable.
  • the use of a fuel gas oxygen burner for the heat treatment furnace significantly affects the dew point temperature in the heat treatment furnace.
  • the dew point temperature can change greatly within a short time.
  • increases in the dew point temperature can be counteracted quickly and efficiently, and the dew point temperature can be regulated to the desired desired value.
  • the invention is furthermore particularly suitable as a measure for a so-called Flue Gas Management System for reducing exhaust-induced water fractions in heat treatment furnaces.
  • dried air is supplied to the heat treatment furnace.
  • the dried air or a mixture of (ambient) air and dried air can be supplied to the heat treatment furnace.
  • the reduced Proportion of water in dried air can further prevent the formation of hydrogen from the air in the heat treatment furnace.
  • the heat treatment furnace preferably has at least one chamber or zone.
  • chambers can be physically separated units of the heat treatment furnace.
  • zones can also be called
  • the regulation according to the invention of the dew point temperature is carried out for the at least one chamber or zone. Depending on the length and size of the
  • Dew point temperature can be performed over the entire heat treatment furnace as a zone or the heat treatment furnace can be divided into several zones, for each of which the inventive control of
  • Dew point temperature is carried out separately.
  • the dew point temperature control according to the invention is carried out individually and independently of each other for each chamber or zone.
  • the dew point temperature of each chamber or zone can be suitably regulated to a separate, individual desired value.
  • the amount of nitrogen introduced is determined on the basis of the actual value of the dew-point temperature detected in the respective chamber or zone and on the basis of the individual desired value of the dew-point temperature determined for the respective chamber or zone.
  • an amount of supplied air based on the determined in the heat treatment furnace actual value of
  • Dew point temperature is determined such that the actual value of the dew point temperature is controlled by the specific amount of nitrogen supplied and supplied air to the target value.
  • the dew point temperature can thus be regulated even more flexible.
  • the ratio of the nitrogen-air mixture in the heat treatment furnace can be set more flexible and optionally on different workpiece materials are adjusted.
  • an upper limit of the dew point temperature is determined by the amount of air supplied /
  • a lower limit of the dew point temperature is preferably determined by the amount of nitrogen supplied. The set target value is then within the range of lower and upper limit.
  • the dew point temperature to target values between -5 ° C and -60 ° C, in particular between -10 ° C and -40 ° C, regulated.
  • the dew point temperature can be controlled by means of the method according to the invention on the one hand to target values less than a minimum possible dew point temperature for a pure air atmosphere of about -10 ° C.
  • the dew point temperature can be controlled to target values greater than a dew point temperature for a pure nitrogen atmosphere of about -60 ° C.
  • the amount of nitrogen at high speed is the amount of nitrogen at high speed
  • Heat treatment furnace generally be set homogeneously and without significant local variations.
  • a Carbojet process is used to supply the amount of nitrogen.
  • the Carbojet process and associated Carbojet nozzles or Carbojet lances are sold by the applicant. Small amounts of nitrogen are injected at high speeds of up to 250-300 m / s into individual areas of the heat treatment furnace.
  • the accuracy of analyzers as well as homogeneous gas and temperature distribution can be further improved.
  • the heat treatment furnace by means of at least one
  • premixing fuel gas-oxygen burner in particular at least one Hydrogen-oxygen burner, operated.
  • Premixing fuel gas oxygen burners are characterized by a particularly high heat transfer efficiency.
  • a burner head of the premixing fuel gas oxygen burner while a gas mixture of fuel gas and oxygen is already supplied and not only generated in the corresponding burner head.
  • Premixing burners produce particularly hard flames that are suitable for larger surface areas, too
  • Heat treatment furnace affects the dew point temperature in the
  • the dew point temperature of a heat treatment furnace with premixing fuel gas-oxygen burner can be controlled simply and reliably.
  • the invention is not limited to the use of premixing fuel gas-oxygen burners, but is also suitable for the use of, for example, external mixing burners.
  • the use of an oxyfuel burner is possible.
  • an oxy-fuel burner does not use air, but rather an oxygen-rich gas, in particular (virtually) pure oxygen as oxidizer.
  • the workpieces are rapidly heated in the heat treatment furnace for the heat treatment.
  • This procedure is known as "Rapid Heating”. Since workpieces for a "rapid heating” process in a short time to very high
  • Temperatures are heated, in particular premixing fuel gas oxygen burner, in particular Hydropox burner, are suitable for a "rapid heating"
  • the rapid heating significantly affects the dew point temperature within the heat treatment furnace. Therefore, the invention is particularly suitable for a "rapid heating" process.
  • the heat treatment furnace locally different material properties are preferably produced by local heat treatment. This procedure is generally known as "tailored properties". For example, certain areas of a workpiece may be press-hardened, and other areas may be formed such that they have ductility and thus can absorb more energy by plastic deformation.
  • Possibilities for the production of "tailored properties”, ie of such locally different properties, can be, for example, a targeted influencing of alloy components of corresponding semi-finished products, a production of so-called “tailored welded blanks", ie blanks which are made of different materials, partial (local) Heating by means of inductive or conductive heating technologies, a partial tempering of certain areas of the press hardening tools by local heating, a partial tempering of press-hardened components and / or masking of certain component areas
  • Heat treatment furnace in which the respective different properties of the workpieces are produced, different temperatures and different dew point temperatures prevail.
  • the dew point temperatures of the individual zones can be regulated in a particularly simple manner independently of each other.
  • the heat treatment furnace is used for a region-wise austenitization.
  • This procedure is commonly known as tailored austenitizing.
  • different zones of the heat treatment furnace can also have different temperatures and different temperatures in a "tailored austenitizing" process
  • the method according to the invention is also particularly suitable for controlling the dew point temperatures in the course of a tailored austenitizing process.
  • the invention further relates to a heat treatment furnace for a heat treatment of workpieces. Embodiments of the heat treatment furnace according to the invention will be apparent from the above description of the
  • Figure 1 schematically an embodiment of an inventive
  • Heat treatment furnace for a heat treatment of workpieces and
  • Figure 2 schematically shows an embodiment of a method according to the invention as a block diagram.
  • FIG. 1 A preferred embodiment of a heat treatment furnace according to the invention for a heat treatment of workpieces is shown schematically in FIG. 1 and designated by 100.
  • the heat treatment furnace is in this example as a
  • Roller hearth furnace 100 formed.
  • roller hearth furnace 100 On a plurality of rollers 103, workpieces 102 are transported through the roller hearth furnace 100 (from left to right in FIG. 1).
  • the roller hearth furnace 100 has two zones (101 a and 101 b), the
  • Heat treatment technology are separated from each other. In the two zones 101 a and 101 b, two different process steps of the heat treatment of the workpieces 102 take place.
  • the zone 101 a has a premixing fuel gas oxygen burner 105 (shown only schematically). The premixing
  • Fuel gas oxygen burner 105 is in this example as premixing
  • Hydrogen-oxygen burner in particular as a Hydropox burner trained.
  • the Hydropox burner 105 generates in the zone 101 a a comparatively high
  • workpieces 102 When passing through the zone 101a, workpieces 102 are first heated to a high temperature in a short time, in particular according to a "Rapid The workpieces 102 then pass through the holding zone 101 b and are homogenized therein.
  • Roller hearth furnace 100 adapted to an embodiment of a
  • each of the zones 101a and 101b respectively comprise measuring instruments 110a and 110b, which are connected to a computing unit 120, in particular a control unit, for example a control cabinet, indicated by reference numeral 1 10.
  • a computing unit 120 in particular a control unit, for example a control cabinet, indicated by reference numeral 1 10.
  • a control unit for example a control cabinet, indicated by reference numeral 1 10.
  • method step 201 by means of Measuring instruments 1 10a and 1 10b each an actual value of the dew point temperature of the zones 101 a and 101 b determined.
  • an amount of dried air and an amount of nitrogen are determined in the control unit 120 in step 202.
  • a nitrogen-air mixture is determined, which forms the atmosphere of the respective zone 101 a and 101 b of the roller hearth furnace 100.
  • the dew point temperature of the respective zone is changed.
  • the amount of dried air and the amount of nitrogen are determined such that the actual value of the dew point temperature of the respective zones 101 a and 101 b is regulated to a predetermined desired value.
  • the desired values for the two zones 101 a and 101 b may be the same or different.
  • the control unit 120 is connected to a gas control unit 130, indicated by reference numeral 125.
  • the gas control unit leads the specific amount
  • Roller hearth furnace 100 a container for dried air 140 and a container for nitrogen 150, which are respectively connected via lines 141 and 151 to the gas control unit 130.
  • the line 151 includes an evaporator 160.
  • the gas control unit 130 is connected via lines 130a and 130b to the zones 101 a and 101 b and At step 203, the zones 101a and 101b, respectively, are supplied with the amount of dried air and nitrogen.
  • the quantities of dried air and nitrogen can in each case be supplied via separate lines to the zones 101a or 101b or via one or more common lines per zone. If the amounts of nitrogen and dried air to the zones 101 a and 101 b fed via separate lines, the amounts of nitrogen can be supplied to the chambers 101 a and 101 b in particular via a high-speed Carbojet method.
  • the process begins again at step 201 with determining the actual values of the dew point temperatures of the zones 101a and 101b of the roller hearth furnace 100.
  • the dew point temperatures are thus continuously monitored and controlled in real time to the predetermined target values.
  • control unit 120 120 arithmetic unit, control unit

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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)
  • Tunnel Furnaces (AREA)

Abstract

La présente invention concerne un procédé de réglage du point de rosée d'un four (100) destiné au traitement thermique de pièces (102), ainsi qu'un four (100) destiné au traitement thermique de pièces (102). Selon ce procédé, on introduit de l'azote et de l'air dans le four de traitement thermique (100), et on définit la quantité d'azote introduite en fonction d'une valeur réelle du point de rosée mesurée dans le four de traitement thermique (100), de façon à faire correspondre la valeur réelle du point de rosée à une valeur de consigne au moyen de la quantité d'azote introduite ainsi définie.
PCT/EP2014/000892 2013-04-25 2014-04-03 Procédé de réglage du point de rosée d'un four de traitement thermique WO2014173494A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP13002194.2 2013-04-25
EP13002194.2A EP2796570A1 (fr) 2013-04-25 2013-04-25 Procédé de régulation d'une température de point de rosée d'un four de traitement thermique

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Publication Number Publication Date
WO2014173494A1 true WO2014173494A1 (fr) 2014-10-30

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EP (1) EP2796570A1 (fr)
WO (1) WO2014173494A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11149327B2 (en) 2019-05-24 2021-10-19 voestalpine Automotive Components Cartersville Inc. Method and device for heating a steel blank for hardening purposes

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT202000013285A1 (it) * 2020-06-04 2021-12-04 Danieli Off Mecc Procedimento e apparato per il riscaldo di prodotti siderurgici
DE102022118249A1 (de) 2022-07-21 2024-02-01 Thyssenkrupp Steel Europe Ag Verfahren zur Einstellung einer Ofenatmosphäre in einem Wärmebehandlungsofen

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2570503A2 (fr) * 2011-09-15 2013-03-20 Benteler Automobiltechnik GmbH Procédé et dispositif de chauffage d'une platine préenduite en acier

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008009818A1 (de) 2008-02-19 2009-08-20 Linde Ag Verfahren und Vorrichtung zur Wärmebehandlung von Werkstoffen

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2570503A2 (fr) * 2011-09-15 2013-03-20 Benteler Automobiltechnik GmbH Procédé et dispositif de chauffage d'une platine préenduite en acier

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11149327B2 (en) 2019-05-24 2021-10-19 voestalpine Automotive Components Cartersville Inc. Method and device for heating a steel blank for hardening purposes

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