SILICON & ELECTRICAL STEEL HEAT TREATMENT

Backed up by world leader LOI technology for heat treatment furnaces LOI Wesman enjoys leadership in the field of both semi-finished as well as finished electrical steel.

For heat treatment of semi-finished electrical steel such as punched rotor or stator laminations the Roller Hearth Furnace involve several zones for different steps of heat treatment. The laminations initially 

undergo a decarburization annealing under reducing atmosphere in order to achieve the desired carbon in the product. To generate passivity against rusting the charge materials then undergo blueing in a humid atmosphere at a predetermined temperature. Finally the charge materials are cooled down to atmospheric temperature. The heating medium for such furnaces are either electricity or indirectly fired radiant tube burners.

The resulting products from these furnaces show improved electrical properties consistently for a long period.

In the field of finished silicon steel LOI Wesman enjoys leadership as a furnace builder. There are continuous heat treatment line in the field of Non-grain (CRNGO) oriented as well as grain oriented (CRGO) steel.

The process of heat treatment of grain oriented  Silicon steel involves several steps like decarburization and MgO coating, high temperature annealing, re-crystallization annealing and final coating.

The annealing processes are carried out under protective atmosphere in the form of Hydrogen.  De-carburization and coating is done in a continuous line with coil un winder, heating up, soaking, cooling down at different rates of cooling and Magnesium Oxide coating and coil winder.   The wound coils are then undergo high temperature annealing in batch type multi stack bell annealing furnaces for grain orientation. The magnesium oxide lining forms a glassy layer over the substrate.

The high temperature annealed materials undergo a further re crystallization annealing followed by final painting in a continuous annealing line.

For non-grain oriented silicon steel the high temperature annealing is not required. CRNGO is treated in a continuous line for re crystallization annealing and final coating.