6/19/2012 By Meredith Staub
Written by By Meredith Staub
Steel is one of the most utilized materials in the world. About 1.3 billion tons are produced every year—and 500 million tons of that steel is recycled, equivalent to 180 Eiffel Towers every day. That’s more than recycled paper, aluminum, plastic, and glass combined!
MechSE Professor Brian G. Thomas is particularly interested in this essential material. His Continuous Casting Consortium (CCC), a cooperative research effort that involves some of the biggest names in the steel industry, is continually working to understand and improve the steel-making process. Members of the CCC come to MechSE from all over the globe, including Sweden, China, Japan, the Netherlands, and Korea.
“What most people don’t realize,” said Seid Koric, Thomas’ colleague and an adjunct assistant professor in MechSE, “is that Brian Thomas is the go-to guru for the steel industry. Everybody in the world comes to CCC and the University of Illinois to solve their problems, not just the producers in the United States.”
Continuous casting produces over 96% of the steel in the U.S. The process begins with molten steel being poured into an open-ended, bottomless, water-cooled mold. As it flows downward through the mold, a thin shell of solid steel solidifies and cools along the inside of the mold, and thickens as the molten steel moves further and further down. The shell is pulled from the bottom of the mold, where it acts as a container for the steel that is still liquid inside. Like a water balloon, the soft, weak shell must be supported below the mold to prevent it from bulging out of control. The shell is continuously pulled through the supporting and straightening rollers and eventually the steel cools all the way to the center. It is then cut to a predetermined length and sent for rolling and further processing into different shapes according to the needs of the client manufacturer.
“If you can get the whole process to run a steady state, that’s how you make your highest-quality steel. You don’t want things to deviate,” Thomas said. “Everyone worries about random failures, because they can cause serious calamities in the real world. But it’s not really random if you look at steel parts in detail. It’s most likely some little inclusion or some problem with the steel, and most of those problems go right back to the casting process. So that is why we are looking at improving the casting process."
Thomas and his group are looked to as experts in this crucial process, and they continually work to make it more efficient and to minimize weaknesses and defects in the product. Their main tool is to develop comprehensive mathematical models of the continuous casting process for casting steel slabs, in order to improve understanding of and optimize the process.
“We want to understand exactly how breakouts occur and what the warning signs are, so we can prevent that. We study breakouts quite a lot—not just for that reason, but because a breakout event gives you an insight into the process that you don’t usually get. You get to see the process before it’s all finished, and that helps us to calibrate our models and lets us solve the other problems, too,” Thomas said.
Thomas joined the department in 1985, after receiving a bachelor’s degree
in Metallurgical Engineering from McGill University and a PhD in Metallurgical Process Engineering from the University of British Colombia. He founded the CCC in 1991 as a vehicle for continuing the work that originated with his National Science Foundation Presidential Young Investigator Award. It is a cooperative research effort between the University of Illinois, corporate members of the steel industry, and the government (through the NSF).
Some of the problems his group has been able to solve have been specific practical problems for the steel industry, through the involvement of the steel corporations in his CCC. The member companies of the CCC invest funding and interest into Thomas’ work, as his achievements can directly improve their processes.
“They are interested in an improved understanding of the process and things that they can do to make the process better,” he said. “Rather than tell them, ‘Do this and your defects go away’—that might work for one specific case, if we get lucky—I think the better way we do it is to explain: here is exactly how this defect occurs (and each steel company can usually find their own way to prevent that from happening in their plant). So I take it that my main task is to really understand where the defects are coming from, and by getting all the details nailed down, we can find out the most optimal way of fixing the problem.”
The CCC holds an annual meeting for the member companies, in which Thomas’ students show presentations on what they have been researching, as well as several workshops for the member companies. At these workshops, the member companies give their own presentations on a certain predetermined topic, such as longitudinal cracks, and compare data and methods of fixing the problem.
“People don’t like to talk about defects in public,” Thomas said. “But by getting people to agree that everybody attending has to give a presentation, that’s how you get into the workshop. It’s been really successful because they have really opened up and have talked about all kinds of stuff. These are ‘competitors,’ but they all have the same problems.”
In this way, the CCC encourages not only positive collaboration between the research group and industry, but also between the companies themselves.
The projects of the CCC vary, and cover multiple aspects of the process such as: optimizing fluid flow; controlling heat transfer and secondary cooling; predicting precipitate formation; predicting cracks; and studying the interface between the solidifying steel and the mold wall. To look at all of these different aspects of the process, Thomas has collaborated with researchers from different fields.
“My research is really meant to understand all aspects of it because it’s a really complicated, coupled, multi-physics kind of process,” he explained. “That’s why I have to team up with people who are the top experts of the different pieces. If I want to do controls, I team up with a controls expert, such as Professor Joseph Bentsman (in MechSE). If I want to do fluid flow, I team up with a fluid flow expert, such as Professor Pratap Vanka (in MechSE). If I want to do stress analysis, I team up with an ABAQUS expert, such as Dr. Seid Koric. I’ve had successful collaborations with many colleagues at the University of Illinois, and with a lot of different groups around the world. So I contribute the modeling piece, and the big picture application piece, and then they contribute their expertise.”
His research group includes undergraduates, graduate students, PhD students, and visitors from other universities and steel companies. The students come from a number of engineering fields, such as materials, electrical, or nuclear, but most come from MechSE.
“I like the mechanical science and engineering base because the students have a good mathematical rigor,” Thomas commented. “They know their mechanics better, and therefore they can be better at doing the computational modeling. What I try to get them to do is to apply the computational modeling to a real-world process, and make a difference to that process to solve that problem. They usually graduate and get good jobs in industry applying that modeling methodology to very different problems.”
Employment in the steel industry in the United States dropped from 521,000 jobs in 1974 to only 151,000 in 2000. The tonnage produced, however, has continuously increased with the improved efficiency and productivity in the industry.
The new steel employees, Thomas said, “really need to understand the process. Because even though it is automated, there are things that still can go wrong, things you have to do to improve things in the future. So that’s where my research is focused.”
Steel is the most recycled material in the United States. It is far more energy efficient to recycle steel than it is to create new steel, and, most importantly, it can be recycled continuously without losing any of its strength or quality.
“I think it’s worth investing energy and time to make it a better process,” Thomas said. “From my point of view, one of the things I like to think is that we’ve brought the industry forward in their understanding of their own process. In the early days, people didn’t understand what they were doing and got it to work by trial and error. Now they do understand, and I think that’s one of the biggest benefits from the research we have been doing. The industry has come amazingly far.”
More information on his research group and the Continuous Casting Consortium can be found at ccc.illinois.edu.