June 14, 1999 PITTSBURGH, June 8 --- In what could be one of the most important innovations in steel making in the last 30 years, researchers at the University of Pittsburgh's School of Engineering have developed a lead-free alternative to 12L14, a free machining steel commonly used throughout the world. The new steel resulted from research by Anthony J. DeArdo and C. Isaac Garcia, professors of materials science and engineering at Pitt. The research was largely supported by an international consortium of steel producers and users. According to DeArdo and Garcia, their new steel is not only more environmentally friendly, but potentially can be machined more easily than leaded steel.
DeArdo and Garcia used tin to replace the highly toxic lead, which is added to steel to make it easier to machine. The new product, which they term "green steel," not only eliminates an undesirable environmental hazard, but it may also offer cost savings. The researchers' work was conducted through the Basic Metals Processing Research Institute (BAMPRI), which is affiliated with the School of Engineering's Department of Materials Science and Engineering.
A patent for the new lead-free steel was filed by the University of Pittsburgh and is expected to issue this month. The University, through the Office of Technology Management, created an international consortium of steel producers and manufacturers to commercialize the technology. The University also signed a technology licensing agreement with the consortium, which is officially organized as a limited liability
Company (LLC) of steel producers--the Nonleaded Free Machining Steel Consortium, LLC. The producer members of the LLC will produce the lead-free steel commercially, and may sublicense to others as market demand increases.
The consortium includes the University of Pittsburgh; United Alloys & Steel Corporation, of Buffalo, NY; MacSteel, a Division of Quanex Corporation, of Fort Smith, Arkansas; Curtis Screw Company of Buffalo, NY; Saarstahl Steel, AG, of Volklingen, Germany; and Laurel Steel, a Division of Harris Steel Ltd., of Ontario, Canada. Members of the consortium have helped finance the research at Pitt for the past four years. USS/KOBE Steel Company has also been supporting the research at the University, and has the option of joining the consortium by July 31.
University of Pittsburgh Chancellor Mark A. Nordenberg noted that in addition to the scientific significance, the development also has economic implications.
"As the University of Pittsburgh seeks to advance fundamental knowledge through research, it develops technologies and other innovations that promise to fuel the region's and the Commonwealth's economies for many years to come. The development by our faculty members of this new type of steel and the steps that have been taken to translate the discovery into a thriving commercial venture are examples of our commitment to transfer new discoveries from the lab into the global marketplace," Nordenberg said.
"In doing so, the University continues to play a key role in keeping Pittsburgh and Pennsylvania strong by contributing to the economic vitality of the communities we serve," Nordenberg added.
A test of the final product, completed recently at USS/Kobe Steel Company, found that a 220-ton heat of the new steel performed well. The new steel is presently being tested, and Milton Harris, chairman and CEO of Harris Steel, said the company is encouraged by the test results to date. The market for 12L14 steel is between two and three million tons per year, and at approximately $500 per ton, the worldwide potential market is $1 billion-plus for the lead-free steel.
Not only is the lead environmentally undesirable, but it adds production costs as companies need to implement environmental controls to the manufacturing process. Arthur A. Boni, Pitt's director of technology management, estimates that the "green" steel has the potential to save on environmental and machining costs.
"Ever since governments began asking steel manufacturers to reduce their use of lead, researchers have been trying to come up with alternatives," said DeArdo. And the major users of free machining steel are also interested. The most common use for the steel is in automobile parts, and Harris noted that major automakers in the United States and Germany have indicated a desire to use lead-free steel if it were competitively available.
While other researchers have experimented with different steel alloys, DeArdo and Garcia used another tack. "The key was asking the right question. We started with the scientific approach, asking, `What does the lead do, on an atomic level, that makes the steel more machinable?'," DeArdo said.
The researchers studied leaded steel using an atom probe field ion microscope to examine the ferrite grain boundaries. "Once we saw what the lead did, the answer was obvious to us," DeArdo said.
The researchers decided that tin would be the most suitable replacement for the lead, then experimented with different ratios of tin in the steel before coming up with their new product. They found that too much tin made the steel too brittle; too little tin made it harder to machine. The final tin content chosen not only makes the steel more machinable than the existing leaded steel, but also could permit a substantial reduction in the machining cost of final components.
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