Forging Like Rolling With High Reduction of SBQ Long Products

by "Francesco Toschi, Alberto Lainati, Giuseppe Muscara"

Publisher - Primetals Technologies Italy Srl

Category - Engineering & IT

"The Special Bar Quality family comprises a wide range of steel grades, mainly requested by the mechanical constructions and energy, for applications where significant performances are required (eg. stresses, temperatures, working cycles, etc.). To meet these requirements, it is necessary to reach a precise control of both the mechanical characteristics and metallurgy structures along the whole production chain. For semi-product with large dimensions, such as equivalent diameters around 300 mm, this is traditionally obtained through a manufacturing route which comprises the casting in ingots followed by reheating, forging and rolling. After 2010, new processes were investigated and technologies developed to replace the ingot route with a continuous casting followed by controlled high-reduction rolling. In these processes a seamless integration of CCM with rolling is implemented so to obtain the precise control of material flow, applied deformation and working temperatures. By using the proper combination of rolling diameter, speed and applied reduction, a very good control of the metallurgy structure across the whole section can be obtained, so to also remove the internal discontinuities (""voids"") generated during the continuous casting. These processes, which can be defined ""forging-like"", are applicable to several grades also with large semi-product dimensions (300 mm and more). Besides, removing the ingot route means increased yield and productivity, which is very beneficial to the economical management of the plant. An example of this ""forging-like"" process is represented by the high-reduction blooming stand installed by a primary Italian special steel producer. This article describes its main concepts as well as its technology and process features."

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