ESSC & DUPLEX 2019

Quality of stainless steel semi-products is important for the cost-efficient production of final products. Yield losses due to the excessive grinding, losses due to the down-grading or scrapping the whole semi-finished product may impair the profitability of the production. By monitoring the surface quality of the hot slabs during the casting on line, it is possible to get valuable information for making improvements in caster condition and in composition of a steel grade to improve castability and surface quality. This research was concentrating on the monitoring of surface quality of stainless steel, but the same principles apply also for carbon steel. This paper shows how Reveal CAST surface inspection system can be used to identify different types of defects from the hot surface of cast slabs. The paper also describes the relationship between the caster condition and the slab surface quality. As an example, using the reporting tools included in Reveal CAST together with automatic defect detection features, it was easy to find out that with Ti-alloyed austenitic stainless steel, the rate of the sticking defects was clearly higher during summer time compared to winter time. The reason for increased sticking defects during summer time is explained. The same phenomenon was also found earlier, but with much more time-consuming work. Similar studies are easy to do with Reveal CAST. Using Reveal CAST in the hot band inspection, it is possible to evaluate, which of the defects on the slab surface are causing the defects on the rolled strips. Grinding of the rolled strips is clearly more expensive than the grinding of slabs. Monitoring during grinding of the slabs ensures removal of defects without extensive grinding losses. This paper shows that monitoring the surfaces of semi products on line with Reveal CAST can result in cost savings and in quality improvements.