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January 2007
Vol. 4, No. 1
Process Control and Automation Technologies

About the Cover

CSP Production Planning System
Yury Krotov, process analyst, Steel Dynamics Inc., Flat Roll Division, Butler, Ind. (yury.krotov@stld.com)

A new system for planning of hot mill production was developed and implemented at Steel Dynamics’ Flat Roll Division. The application is currently used for scheduling optimization of the CSP area, as well as for inventory forecasting for the entire plant.

Cast Floor Robotics — Concept and Test Results
Andreas Jungbauer (left), product manager — continuous casting, Johann Penn (second from left), head of project management — continuous casting, Josef Lanschützer (second from right), vice president — long products, and Helmut Ebner (right), research manager — continuous casting, Siemens VAI, Linz, Austria (andreas.jungbauer@siemens.com)

Siemens VAI is developing a fully automatic operation of casting floor activities. A mockup of ladle, tundish and mold were laboratory tested, and the results and realizations are discussed.

Mixed Grade Model Development and Implementation at Dofasco
Stephen Daeyoung Chung (pictured), steelmaking technology, Keith Delaurier, process automation, Blair MacCuish, process automation, and Brian Cuthbertson, process automation, Dofasco Inc., Hamilton, Ont., Canada (stephen_chung@dofasco.ca, keith_delaurier@dofasco.ca, blair_maccuish@dofasco.ca, brian_cuthbertson@dofasco.ca)

A new model was required at Dofasco to accommodate frequent grade changes. A new equation was also developed to predict transitional chemistry. The model and equation were integrated into level 2 controls to determine optimal cut locations.

Thinking Outside the Storage Box
Matthew A. Rosato, formerly of JNE Automation Ltd., Hamilton, Ont., Canada

Warehouse storage and retrieval entail the methodical arrangement of goods. This paper focuses on the controls and administrative software developed for a fully automated coil handling facility — a first of its kind in North America.

Hot Metal Process Improvement at Mittal Steel USA – Sparrows Point via Technology Implementation Including a Sensor-based Sulfur Sampling System
Rick Fash (top left), division manager — steel producing, William Howanski (top right), division process manager, and Danny Neith, process engineer — BOF, Mittal Steel USA – Sparrows Point, Sparrows Point, Md. (rick.fash@mittalsteel.com, bill.howanski@mittalsteel.com); David Patterson (bottom left), sales service engineer, and Randall P. Stone (bottom right), senior product manager, Heraeus Electro-Nite Co., Langhorne, Pa. (dpatterson@electro-nite.com, rstone@electro-nite.com); and Mark Borsody, salesman, Hart Metals, Tamaqua, Pa. (mborsody@melmagnesium.com)

Initial advantages of using a hot metal Celox sulfur probe at the Sparrows Point desulfurizer included accuracy and repeatability, as well as significant time savings to the operation. As the probe became part of the standard operating procedure, a cost savings from the decreased amount of reagent was also recognized.

Digital Visual Inspection of Coils
Mohammad. B. Assar (left), quality engineer — finishing, Larry Romanauski (right), engineer — quality systems, inspection, Matt Kremer, manager — quality systems, Margaret Krolikowski, manager — finishing, quality systems, and Joe Franklin, process improvement engineer — finishing, Mittal Steel USA – Cleveland, Cleveland, Ohio (mohammad.assar@mittalsteel.com); Mike L. Elliott, manager of product development, and Randy A. Stankie, director of engineering, Benchmark Automation, Cleveland, Ohio (rstankie@benchmarkautomation.com)

A digital visual inspection system was implemented at the Mittal Steel USA – Cleveland 84-inch cold mill to review coil quality, to establish the validity of
customer claims, and to monitor and troubleshoot mill operations. The system, its uses and some of its practical applications are described.

Inclusion Control of Fe-16%Cr Stainless Steel Melts by Aluminum Deoxidation and Calcium Treatment
Joo Hyun Park, Dong Sik Kim, Sang-Beom Lee and Yun Yong Lee, Stainless Steel Research Group, Technical Research Laboratories, POSCO, Pohang, Korea (basicity@posco.co.kr)

Introduction
Chromium stainless steels have been widely used for corrosion-resistant materials at room or high temperatures, as well as construction materials. The effect of deoxidation equilibria on the inclusion formation is important from the viewpoint that the oxide inclusions probably deteriorate corrosion resistance and cause the surface defects and cracks during deep drawing or spinning manufacturing. In stainless steelmaking processes, deoxidizers such as silicon and/or aluminum have been added in the AOD (argon oxygen decarburization) converter or ladle in accordance with steel grades. Nevertheless, the deoxidation equilibria of chromium stainless steels have not widely been investigated, while those of chromium-nickel steels have been studied by many researchers.1–5

Kishi et al. reported the aluminum-oxygen equilibria of the 20 mass% Cr steel equilibrated with the CaO(-BaO)-Al2O3-TiOx slags at 1,873 K using alumina crucible.6 Park et al. investigated the removal kinetics of alumina inclusions after aluminum deoxidation of 16 mass% Cr steel with the CaO-SiO2-Al2O3 and CaO-SiO2-CaF2 slags at 1,873 K by taking the nucleation and growth mechanism into account.7 However, in these studies, the thermodynamic equilibria between aluminum and oxygen in molten chromium steel under the condition of unit activity of alumina could not be examined due to the slag phase. Nakajima and Mizoguchi,8 and also Luo9 tried to directly observe the behaviors of inclusions on the 16 mass% Cr steel melt surface by employing a confocal scanning laser microscope (CSLM) and explained the phenomena based on a theory of capillary interaction and contact angle of particles with the steel melt. However, they focused on the surface physics rather than thermodynamic equilibria between oxygen and aluminum or silicon in the chromium steel melt. Recently, Suzuki et al. investigated the deoxidation equilibria of chromium stainless steel with silicon and obtained the equilibrium constant of the formation reaction of SiO2 and the interaction coefficient of silicon as a function of chromium content.10 Although it is certain that their experimental results are very useful in silicon deoxidation in stainless steelmaking processes, the details of aluminum deoxidation equilibria of chromium steel have not yet been fully understood.

Therefore, in the present study, the aluminum-oxygen equilibrium and the morphology of inclusions as a deoxidation product are investigated. Furthermore, the effect of calcium addition on a change of inclusion chemistry are discussed.