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
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
  • C21D8/1227—Warm rolling
• • 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
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
  • C21D8/1222—Hot rolling
• • 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
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/1261—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest following hot rolling

Definitions

• the present invention relates to a method for manufacturing mild steel, in particular mild steel with a low coercive field for the manufacture of magnets used in particle accelerators or similar installations, such as a storage ring, etc. .
• particle accelerators of a certain size require magnets from a steel with a very specific set of characteristics.
• this steel has sufficient mechanical strength and specific magnetic properties, such as a relatively low coercive field with a slightly dispersed average value, an absence of aging of the magnetic properties, a magnetic permeability guaranteeing high levels of induction as well as a very low level of magnetic loss making it possible to work with sheet thicknesses equal to or greater than 1.5 mm.
• the flatness of the constituent parts of the magnet must be such as to ensure a high filling coefficient, preferably greater than 98%.
• These parts must also have very tight thickness tolerances, have no mechanical tension, be practically free of carbon, resist corrosion, be able to be machined and cut easily, and finally be able to be as thick as possible.
• the invention aims to present an economically justified process for the treatment of a steel with a view to obtaining a mild steel meeting as much as possible the criteria defined above.
• This process is characterized by the fact that one starts from a steel corresponding to the following composition: C ⁇ 1% If ⁇ 1% Mn ⁇ 1% P ⁇ 0.100% S ⁇ 0.100% N ⁇ 0.100% Al ⁇ 0.250%, that slabs are formed from such steel, that these slabs are subjected to a rolling process conducted at least in part in the ferritic phase until a strip with a thickness of 1 to 12 mm is obtained and that this steel strip undergoes self-annealing and / or is subjected to a controlled annealing, so as to obtain crystallization of the rolled steel in the ferritic phase.
• the slabs thus obtained are reheated in order to increase the malleability of the steel and thus facilitate subsequent rolling.
• This reheating is carried out for example at a temperature of 900 to 1250 ° C.
• This rolling is carried out until a steel strip with a thickness of 1 to 12 mm is obtained, depending on the application envisaged.
• This steel strip thus obtained undergoes self-annealing and / or is subjected to a controlled annealing so as to obtain a crystallization identical to that of rolled steel in the ferritic phase.
• the steel coil is introduced into an oven for a determined time and is brought to a temperature which is in particular a function of this residence time in the oven.
• controlled annealing is carried out at a temperature between 400 and 910 ° C. for a period of 3 minutes to 48 hours and preferably from 30 minutes to 48 hours, while ensuring that the periods of stay in the oven shorter correspond to the highest annealing temperatures and conversely that the longest times correspond to the lowest temperatures.
• This pickling preferably takes place before annealing.
• pickling and annealing can, if necessary, be carried out simultaneously, for example in a reducing atmosphere rich in hydrogen.
• advantageously cylinders are used. rolling lubricated thereby reducing the friction effect on the surface of slabs and steel strips during rolling.
• the slabs obtained were subjected to reheating for 1 hour 30 minutes at a temperature of 1250 ° C.
• the thickness of the steel strip obtained was 2.5 mm. Then took place the winding of the steel strip at an average temperature of about 680 ° C and therefore it undergoes self-annealing. Finally, a conventional chemical pickling was applied to the steel strip after having laid it flat and cut into sheets.
• the grain size in the finished strip was 5 ASTM and the coercive field was 95 A / m.
• the slabs formed from such a steel were subjected to reheating at a temperature of 1250 ° C. for approximately 1 hour and a half.
• the rolling was carried out on a continuous finishing train. At the entry of the latter the temperature of the steel was of the order of 900 ° C. and at the exit of the order of 750 ° C. The strip was then wound at a temperature of 750 ° C. Subsequently, a cold rolling finish, namely a skin pass of 2%, was carried out. After a conventional chemical pickling in a sulfuric medium, continuous annealing was carried out at a temperature of 825 ° C. and this for a period of 90 seconds. Then finally the strip was subjected to a "HOWAQ" quenching at 400 ° C. and to monitoring for 200 seconds at 400 ° C. followed by a further etching with formic acid and a new skin pass of 0, 2%.
• a cold rolling finish namely a skin pass of 2%
• the grain size in the finished steel strip was 2 ASTM and the coercive field was 80 A / m.
• the reheat temperature was 1050 ° C for 2 hours.
• the average temperature at the paver was 840 ° C.
• the winding temperature was 730 ° C.
• This sheet then presented a coercive field of 50 A / m and an induction of 1.95 Ts at a magnetic field of 100 A / cm.
• the reheat temperature was 1000 ° C for 2 hours 15 minutes.
• the inlet temperature of the paver was 900 ° C and the outlet temperature of 675 ° C.
• the winding temperature was 200 ° C and the thickness of the strip leaving the finisher was 0.8 mm.
• the steel obtained had an ASTM 1 grain and a coercive field of 40 A / m.
• the induction was 0.8 Ts at a magnetic field of 40 A / m.
• the reheating temperature was 1250 ° C for 1 hour 30 minutes.
• the average temperature in the paver was 760 ° C.
• the winding temperature was 300 ° C and this was followed by chemical pickling.
• Annealing was carried out in a hydrogen medium at a temperature of 750 ° C.
• the steel obtained had an ASTM grain of 5-6.
• the coercive field was 110 A / m.
• a calamine removal treatment can, if necessary, take place at different stages of the process.
• This treatment can be a chemical pickling or a mechanical descaling such as, respectively, a reduction of the metal oxide by a reducing agent, such as for example hydrogen, or a shot peening.
• the rolled steel strip can be kept at a substantially uniform temperature relatively low at most 150 ° C before its possible winding.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Crystallography & Structural Chemistry (AREA)
• Mechanical Engineering (AREA)
• Electromagnetism (AREA)
• Metallurgy (AREA)
• Thermal Sciences (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Metal Extraction Processes (AREA)
• Lubricants (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
• Heat Treatment Of Steel (AREA)
• Manufacturing Of Steel Electrode Plates (AREA)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (6)

Cited By (2)

Citations (9)

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• 1994
  • 1994-02-07 BE BE9400140A patent/BE1007927A3/fr not_active IP Right Cessation
• 1995
  • 1995-02-02 EP EP95200245A patent/EP0681031B1/de not_active Expired - Lifetime
  • 1995-02-02 AT AT95200245T patent/ATE212070T1/de active
  • 1995-02-02 DE DE69524989T patent/DE69524989T2/de not_active Expired - Lifetime
  • 1995-02-02 DK DK95200245T patent/DK0681031T3/da active
  • 1995-02-02 ES ES95200245T patent/ES2171494T3/es not_active Expired - Lifetime

Patent Citations (9)

Non-Patent Citations (2)

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