Technological advances in the production of
new types of steel are driving steel producers forward in their
quest to develop new products, but the needs of customers have
settled behind the wheel as dual-phase and transfer-induced
plasticity (trip) steels come to the fore.
Steelmakers such as ArcelorMittal, the
world's largest producer, are heavily involved in the
development of new advanced high-strength steels (AHSS),
including dual-phase steel, trip steel and the next stage,
which is coming to be known as twinning-induced plasticity
"With our operations in the Americas and in
Europe, ArcelorMittal is focused on the high-value-added
products," Pinakin Chaubal, director of process research for
Mittal Steel USA Inc., Chicago, said. "What we are continuing
to look for is ways to make steel a more formable product. That
really is being driven by increasing needs for safety and fuel
efficiency on the part of our (automotive) customers."
Pittsburgh-based Integ Process Group Inc. is
mining some of the same territory with its Hot Strip Mill Model
(HSMM), an off-line PC software product that allows steelmakers
to simulate the steel rolling process for hot mills. In
partnership with the American Iron and Steel Institute (AISI),
Integ is marketing the HSMM to mills worldwide-and finding
customers that are seeking ways to use more dual-phase and trip
"We are now adding features to the model,
including dual-phase steels," Richard Shulkosky, president of
Integ Group, said. "We're finding that's what the customers
Such steels are considered advanced
high-strength steels and are seen to a large degree as key to
steel potentially gaining market share among automotive
The AISI, through its Market Development
Committee and various customer partnerships, is promoting the
use of AHSS-lighter, more formable steels-in vehicle
construction. The use of such steels maintains vehicle
efficiency but improves crashworthiness.
Chaubal said ArcelorMittal wants to maintain
its position as one of the leading suppliers to the North
American automotive industry through a multifaceted approach
using more AHSS. The company in May announced plans to upgrade
the continuous heat-treating line at its Burns Harbor, Ind.,
facility so it can produce more such steels.
"We are trying to be aggressive not only in
terms of (increasing) the number of products we produce, but
also in the timing of bringing these concepts to the market,"
he said. "The customers want to see these more formable steels
brought to the market more quickly. That's one of the things
that is driving our capital investment (in the upgrade of the
continuous heat-treating line). It's all being driven by the
needs of the automotive industry."
ArcelorMittal's involvement goes beyond its
automotive customers to working with stampers. As new steels
are developed, stampers must learn of their formability
characteristics and have to adapt to use new tools and/or
materials in their processes. ArcelorMittal is among those
employing Integ's HSMM.
"We are involved with customers at every
stage of the game," Chaubal said. "You cannot be a high-end
player in steel without being able to understand what will be
happening to your steels at the customer's manufacturing plant.
Our focus right now is on the dual-phase and trip steels, but
we are not going to stop there. We are now looking at the twip
steels, which provide higher strength and higher formability
than you get with the trip steels. It's an entirely new
The HSMM is not new, but is moving into
stages of additional development. The project was launched in
2003 and the first model was sold midway through 2004 to the
Decatur, Ala., mill of Nucor Corp., Charlotte, N.C.
The hot-rolled development group at Stelco
Inc., Hamilton, Ontario, has relied heavily on the Integ HSMM
to support recent developments involving advanced high-strength
steels with good success. Stelco used it most recently during
the Phase II hot-strip mill upgrade at its Lake Erie Steel
plant in Nanticoke, Ontario.
"In many instances, in part due to the HSMM,
our initial mill development trial process conditions are very
close to the final optimized manufacturing conditions, thus
dramatically reducing time to market of new products and
development costs," Peter Badgley, Stelco's manager of product
development and applications, said.
"Near-optimal process conditions can be
identified off-line, eliminating trial and error in the
manufacturing process," Badgley added. "This has dramatically
reduced the development time for new products."
The model was used in the upgrade of the Lake
Erie hot-strip mill to examine the impact of new equipment and
mill practices on product performance, thus allowing
countermeasures to be identified so product performance could
The model also has been integral to the
development program for dual-phase steel undertaken by Stelco.
"Hot-roll dual-phase steels are part of a class of new advanced
high-strength steels that achieve their product properties
through the thermal cooling trajectory in the run-out table, or
cooling section, in the hot strip mill," Badgley said. "These
products are processed in the final stage at temperatures as
low as 100 degrees Celsius (212 degrees Fahrenheit) vs.
traditional cooling temperatures above 500 degrees Celsius (932
Badgley said Stelco has achieved a number of
successes with use of the HSMM and likely will see more as
improvements to the model are developed.
"The Integ HSMM has been used to help
successfully develop value-added hot-roll products such as
dual-phase and stretch-flange steel for automotive applications
as well as new line pipe steels for the oil and gas industry,"
he said. "As the software is continually improved with enhanced
capabilities, it may be possible in the future that the
software will evolve from an off-line simulative development
tool to one that is used on-line in real-time in the
The software model is one of several
technologies developed under AISI's advanced process control
program, a cooperative effort between steelmakers and the U.S.
Energy Department. Integ sells the model to steelmakers,
research organizations and universities. Eighteen models are in
use around the world, four from its original partnership group
and 14 sold by Integ since the program launch. Sales of the
model have generated $90,000 in royalties to AISI thus far. One
quarter of those are returned to the Energy Department.
The model simulates the hot-rolling process
for a variety of steel grades and forecasts microstructures and
properties, allowing users to achieve deeper insight into
operations. The program also predicts temperatures, forces,
microstructure evolution and final mechanical properties of
plate or strip steel.
Shulkosky said customers have become more
interested in the model in recent years and now want to see two
more developments the ability to use more AHSS, including the
dual-phase and trip steels, as well as a migration from the
current off-line model to an on-line model.
"A lot of people are interested in it,"
Shulkosky said recently. "Right now they want to add more
steels to it," he said. "That's happening globally. They want
to see more dual-phase and trip steels and that's what we are
working to give them."
Much of that interest springs from the runout
table on a hot-strip mill. Shulkosky said customers want to use
HSMM in conjunction with a runout table control model to
measure qualities and adjust spray banks to ensure temperatures
hit pre-established targets.
"With advanced high-strength steels, a lot of
those measurements aren't clear anymore," Shulkosky said. "You
go through a period of cooling, then a pause and then cooling
again. The transfer is more complex and mills want to be able
to model those things to get better quality."
Shulkosky said that Integ wants to take the
process further and now is talking with a company that provides
runout table software to see if that software can be linked to
the HSMM. "The mills used to worry more about rolling," he
said. "Now they are more worried about issues related to the
runout table. Those (issues) are the keys to success with
advanced high-strength steels."
ArcelorMittal, Chaubal said, is focused on
other developments as well. Many are in the areas of
iron-making and blast furnace technology as well as the re-use
of secondary materials. "One of the challenges in iron-making,
when you have the new steel grades, comes after you cast the
slab," he said. "There are challenges in hot-rolling and
cold-rolling that you face with these higher-end products, so
we are directing a significant focus to the cleanliness and
quality of the slab.
"The second area of focus has to do with
cost, quality and productivity. By cost, we are looking at the
impact of the cost of raw materials, environmental regulations
and processing. We are making significant investment in our
production equipment in order to become more efficient and
lessen the cost (of iron-making) on the environment."
Blast furnace research is yielding results in
the form of better refractory performance and the extension of
furnace campaigns, Chaubal said. "Now we can say we are trying
to design blast furnaces for a reline every 20 years. We also
are making improvements in the level of carbon injection. I
would say that 15 years ago we were at 15 kilograms (of carbon
injected) per ton of hot metal produced. Now we are at close to
200 kilograms and on the way to 250."
Environmental stewardship also is the focus
of considerable research. "The big challenge for ArcelorMittal
is on the primary side and the re-use of secondary materials
without losing productivity or efficiency," Chaubal said,
citing such secondary materials as wet and dry dust and sludge
as well as mill scale from steelmaking operations. "That's a
very important challenge. We're looking at ways to reduce the
first generation of those materials and looking at ways to
improve our operations to further the re-use of materials such
as blast furnace dust."a