From ESR to continuous CC-ESRR process: development in remelting technology towards better products and productivity

Abstract

This work describes the development of the Electro Slag Remelting process at Valbruna, starting in the 1997 with an innovative INTECO ESR plant equipped with protective gas hood (for inert atmosphere remelting), electrode change system and fully computer controlled. The second step was made a couple of years later when the plant was upgraded to ESRR® (Electro Slag Rapid Remelting). With this new feature Acciaierie Valbruna was able to obtain ready to roll remelted billets (145, 160 and 200 mm square), getting rid of the traditional forging or blooming operations needed in case of traditional ESR ingot remelting. This was surely a dramatic cut off in product cost accounting and production lead time without loosing any of the special characteristics typical of ESR products. Unfortunately the ESRR® process, very promising in terms of cycle complexity reduction and quality of the product, because of its “batch-type” operation, was uneconomical in regard of productivity of the plant and not feasible in industrial scale. The final step of this development was made at the beginning of 2002 when t he ESRR® plant was upgraded again and equipped with an innovative INTECO automatic manipulator, which resulted in a continuous process. This was the birth of the very first CC-ESRR® (continuous casting electro slag rapid remelting) plant in the world. The first part of this paper focuses o n the development of processes and equipment, giving a brief description of ESR, ESRR® and CC-ESRR® process while the second part describes the results of a series of test remelting used for product and CC-ESRR® process characterization.