Improvement of central soundness in long products from a through process control of solidification and reheating and rolling parameters
This project aims at improving central soundness in rolled long products and thus at increasing significantly the current range of rolled sizes in one heat. Solidification and rolling have been treated as an integrated process. A large number of process parameters have been considered in order to assess their impact on pore closure. The work carried out using coupled experimental and industrial tests as well as numerical simulation has permitted the ranking of those effects and consideration of all of them from a through process point of view, establishing which one (or group) is the most efficient and why. Concerning the solidification process, lower filling velocity and steeper mould taper favour central porosity reduction during ingot casting. For continuous casting, S-EMS results in an even distribution of small pores in the centre but larger total pore volume. The combination of S-EMS and F-EMS gives small pores concentrated in the centre. Additional application of mechanical soft reduction has been proved to reduce central porosity in terms of size and number of pores. The results of thermal soft reduction are conditioned to the hard cooling segment position. The required elongation for pore closure during rolling depends on pore distribution of the stock. An even distribution of small pores in the centre region is preferable to large pores in the metallurgical centre with smaller total fraction of pores. Rolling with larger roll diameter and smaller roll gap, minimising turns between passes, applying a larger reduction in the first passes and reheating and transport strategies to provoke a specific transversal thermal gradient have been shown to promote central soundness.
Bibliographic Reference: EUR 23588 EN (2008), 149 pp. Free of charge
Availability: Katalogue Number: KI-NA-23588-EN-S The paper version can be ordered online and the PDF version downloaded at: http://bookshop.europa.eu
ISBN: ISBN: 978-92-79-09810-9
Record Number: 200910087 / Last updated on: 2008-12-04
Original language: en
Available languages: en