Stabilization of the oil lubricating film by a controlled modification of its viscosity

The soundness of the subsurface region affects the performances of the final rolled products in terms of ductility, toughness and fatigue strength. This behaviour is associated with the microsegregation and with the mechanical stress induced in the solid shell during the casting process interested by the combined action of oscillatory movement of the mould and the pulling induced by the pinch rolls. The performed experimental trials have shown that dangerous micro-segregations and the related damages in the subsurface regions can be avoided through a correct management of the heat exchange fulfilled within the mould. The improvement of the heat exchange has been monitored through thermocouples and the use of stable lubricating layers obtained by the control of a correctly designed viscosity and by an improved thermal conductivity. The experimental trials realized through the use of different lubricants (oil, cheap powder etc. ) on several industrial plants have pointed out satisfactory results even in the realization of semis for the production of re-bars and beams without compromising the economic balance of this production.