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Heat treatment furnace facilities for the steel industry

HICON/H2® annealing and coating lines (ACL)

After cold rolling, the highly worked non-grain-oriented electrical steel strip (NGO) is recrystallized in a horizontal continuous furnace and the grain size is adjusted by secondary recrystallization. A thin layer of insulating lacquer is then applied in-line using a roller coater, in order to reduce eddy current losses in the electrical motor and prevent corrosion. The process steps for this production step are as follows:

  • Multi-stage strip cleaning
  • Rapid strip heating in the heating up section of the continuous furnace (optionally with rapid heating systems up to 500K/s)
  • Option: decarburization to prevent magnetic aging
  • Annealing for recrystallisation and discontinuous grain growth in process atmosphere
  • Controlled cooling in the slow cooling zone and final cooling zone
  • Coating by roller coater and drying in a floater furnace

The special design features of this system deliver the following advantages:

  • Lowest dewpoints due to excellent furnace sealing concept and up to 100 % hydrogen process atmosphere avoid surface oxidation, especially for the highest quality electrical steel grades
    (> 2.5 Si) at annealing temperatures > 1000 °C
  • Homogeneous slow cooling over the width of the strip in the cooling zone for optimum flatness → good punching and laser cutting properties of the electrical steel strip
  • Material temperatures up to > 1100°C feasible, especially for highly-efficient power plant grades such as M230-50A (> 3% Si)
  • Strip as thin as 0.18 mm can be produced for high-frequency applications
  • Resource-saving and tailor-made furnace design to minimize wear part, utility and investment costs
  • The very latest burner/radiant tube technology and rapid heating-up systems for high heating gradients, ensuring efficient decarburization and improved texture (crystalline orientation)
  • Process simulation before heat treatment makes it possible to identify suitable annealing programs to achieve the specified magnetic and mechanical properties
  • Hydrogen regeneration units, which provide hydrogen savings of up to 50 %, are available

Annealing and coating line

Horizontal radiant tube furnace
3D model of a horizontal radiant tube furnace

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Copyright ©2018 by EBNER member of AUSTRIAN CHAMBER OF COMMERCE