2011 August Issue
Full Table of Contents

Flat Product Rolling & Finishing Technologies

About the Cover AIST executives stand together with a panel of leading steel industry executives who took part in the AISTech 2011 Town Hall Forum in Indianapolis, Ind., in May. Pictured (left to right): R. Joseph Stratman, executive vice president, Nucor Corp., and 2011–2012 AIST president; George J. Koenig, president, Berry Metal Co., and Town Hall Forum chair; Theodore F. Lyon, managing director, Hatch Associates Inc.; Keith E. Busse, chairman and CEO, Steel Dynamics Inc.; George F. Babcoke, senior vice president — European and global operations services, United States Steel Corporation; Louis L. Schorsch, president/CEO — Flat Carbon Americas, and executive vice president, ArcelorMittal; William P. Breedlove, executive vice president — marketing and business development, Harsco Metals and Minerals; James R. Darsey, executive vice president — bar products, Nucor Corp.; Jon Delano, money and politics editor, KDKA-TV (CBS), Pittsburgh, and adjunct professor, Carnegie Mellon University; and Ronald E. Ashburn, AIST executive director. A summary of AISTech 2011 and the Town Hall Forum begins on page 37. Cover photographer: Rob Banayote, Banayote Photography, Indianapolis, Ind. Full magazine available in the Members Only Area - NEW UPGRADED FORMAT!

Today, there are 11 rolling mills in the United States that can produce approximately nine million tons of plate per year. ArcelorMittal Coatesville, located 40 miles west of Philadelphia, in Chester County, Pa., is one of these plate mills. The Coatesville facility is the oldest continuously operated steel mill in the country, and celebrated its 200th anniversary on 2 July 2010.

The ArcelorMittal Coatesville plant employs 840 people and covers 950 acres that straddle the Brandywine Creek in and around the city of Coatesville in Southeastern Pennsylvania. The plant produces carbon and alloy plates in gauges from 3/16 to 28 inches, in widths from 48 to 195 inches, and with weights up to 60 tons. These plates are used for construction and mining equipment, bridges, process vessels, and military applications such as ballistic protection for surface ships, submarines and land vehicles.

The story of this mill, from its inception in the early 1800s to its transformation into a producer of the largest and heaviest plates available in North America, is a saga of survival, perseverance, innovation and vision. The achievement of a historic milestone such as a 200th anniversary warrants a look back at some of the pioneers and their mills that allowed this journey to succeed.

The physics of edge buildup of an aluminized steel strip was evaluated with the aid of computational fluid dynamics and metallographic analysis. The mechanism of buildup is explained on the basis of fluid flow patterns and physical properties of the metal coating.

Rejection of a coil can occur when the strip width exiting the last finishing stand is narrower than that predicted by the model. This work analyzes mill production data, identifies key variables that influence the width change and suggests specific corrective actions to improve the work roll temperature model.

This work describes thermomechanical rolling employing a temperature monitor and automated batch rolling. The dimensions of the plate, rectangularity, as well as profile and flatness are discussed.

This work provides an in-depth analysis of descaling. Included is an investigation of water hydraulic systems, which produce pressure across the spray nozzles.

When continuous casting advanced high-strength steels, such as high-aluminum transformation induced plasticity (TRIP) steel grades, conventional lime-silica-based mold powders have shown an inherent instability due to gross reduction of SiO2. The extent of the silica reduction in the base mold powder leads to an alumina increase of as much as 30% in the “working” mold slag composition. The magnitude and inconsistency of this change adversely impacts the physical properties of the slag, which can affect mold heat removal, slag consumption and in-mold behavior. In combination, these factors lead to an as-cast slab surface containing transverse and longitudinal depressions and cracks. As a result, efforts were focused on developing a less-reactive mold powder for casting high-aluminum TRIP steel grades. An initial criterion was to limit the percentage of silica which led to lime-alumina-based compositions. This work describes Stollberg USA’s laboratory development of a series of lime-alumina-based mold fluxes and measurements of key physical properties, evaluation of the powders at ArcelorMittal Global R&D using crucible melted heats, and two production TRIP casts at an ArcelorMittal USA plant and the resulting effect on slab surface quality. In addition, cathode luminescence microscopy, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were used to examine slag films secured during the production casts to determine the nature and distribution of precipitates found in the film. The use of lime-alumina-based mold powders resulted in significant changes in the steel/slag chemical interaction and improved the as-cast slab surface quality.