The measurement and prediction of surface quality by new developments in EMATS and scarfing and the effect of scarfing on surface defects through the mills

Abstract

This report details work undertaken to correlate data obtained from inspection systems in the casting plant, scarfing area and rolling mills in order to track product quality throughout the steel mills. The project was a collaboration between Corus UK Teesside Technology Centre, Arcelor and Scuola Superiore Sant’Anna (SSSA) which was coordinated by Corus. Co-ordination meetings were held twice a year with the partners, at each of the partner sites. Although the project started late due to awaiting RFCS approval, the objectives were completed according to the Technical Annex of the contract which can be found in Appendix 5. All the Tasks were completed by the end of the project, with the exception of Task 2, from Work Package 2 and Task 3 from Work Package 3. Reasons for not completing this work are found in the following section and these were highlighted in previous 6-monthly reports and whilst presenting the mid-term report to the TGS9 Committee. This project did not exceed the overall budget and the project costs from each of the partners were approved after the submission of the mid-term report. Final, audited cost claims are being submitted. Two main inspection systems were tested for use in the continuous casting plant. The first was Conoscopic Holography, which was developed from an industrial prototype where only a partial width of the slab surface was inspected to a system where the entire slab top and bottom faces were inspected. The second was a hybrid Laser-EMAT (ElectroMagnetic Acoustic Transducer) system. This system was demonstrated to work on hot moving steel. Significant work was conducted to analyse data automatically so that a real-time, on-line inspection system could be conducted on plant. Work was undertaken to inspect slabs in the slab yard using a variety of techniques which were compared. This inspection work was used to measure how well the caster was performing, by data mining plant signals and, for Arcelor, equating these with the conoscopic holography readings. Slabs were successfully tracked through the steel mill by the partners and comparisons were made from upstream inspection to the downstream Parsytec system and inspection of the final product. Different scarfing practices were compared. In some instances, for certain steel grades, it was found that scarfing was no longer necessary. Metallographic work was undertaken to assess defects in steel samples to determine the cause of cracking. Upon recommendations from this project, plant practices were changed and the defects no longer arose.