In-line assessment of steel cleanness during the secondary steelmaking process
This research was aimed to develop an appropriate index for steel cleanness in-line assessment during the secondary steelmaking process and at assessing a statistical model of inclusions distribution based on the use of samples taken of liquid and solid-state steel. During the research, new samplers were developed. These samplers were adapted to the simultaneous sampling of slag and steel during vacuum treatment. For certain types of treatment, the sampling of slag and its fast analysis opened the way to study the influence of gunning treatment on slag and on the cleanness of steel. The methodology of the follow-up of inclusion content, by using optical microscopy, was also strongly improved, making the comparison of the results between the laboratories possible. So, statistical approach, including confidence on mean values and size distribution, and modelling development of size distribution were performed on image analysis measurements. The PDA-OES methodology was chosen because it is a fast technique and does not require additional analysis. Data concerning inclusion cleanliness were obtained simultaneously during determination of the steel composition. Results of round robin tests were presented and discussed. They pointed out the importance of the statistical aspect of measurement, sample homogeneity and inclusion density. To illustrate this new way of investigating cleanness, two main groups of steel grades were covered: carbon steels that are generally intended for flat products (low grades for automotive applications) and special steels, such as spring steel or low-alloyed grades. Various heats were examined to set up this new tool and, during one shift, a preindustrial demonstration was conducted, in real time, without delaying the response time of the laboratory. The use of specific cleanness index allows, in real time, the in-line follow up of the process with regard to inclusion content.
Bibliographic Reference: EUR 22032 EN (2006), 77 pp. Euro: 15
Availability: Katalogue Number: KI-NA-22032-EN-S The paper version can be ordered online and the PDF version downloaded at: http://bookshop.europa.eu
ISBN: ISBN: 92-79-01378-5
Record Number: 200618663 / Last updated on: 2006-07-20
Original language: en
Available languages: en