Bell furnace HITT

heat treatmentannealinggas

High-temperature anneals (HTA) of grain-oriented (GO) electrical strip are used to form grains with magnetically advantageous Goss textures through secondary recrystallization. The high processing temperatures (above 1150 °C) and straight hydrogen atmospheres also remove sulfur and nitrogen. A coating of MgO, added in a previous step, inhibits the formation of stickers in the wraps. The safety concept for processing in hydrogen has been adopted from HICON/H2 annealers. The charge is heated by thermal energy radiating from the heating bell and inner cover. The following advantages over other facility types are provided by the EBNER design: Encapsulated, gas-tight workload space ensures significantly lower atmosphere consumption (savings of up to 50 %), compared to alternative designs Rapid heating up and cooling, with possible hydrogen concentrations up to 100 % → significant increase in productivity compared to 100 % nitrogen atmospheres Further reductions in hydrogen consumption are possible if a hydrogen recycling system is installed The homogenous temperature distribution within a stack, provided by patented coil supports and symmetrical heating, ensures: homogenous magnetic characteristics shortened annealing cycles and extends the service life of the inner covers