EFS Profiles
Researchers Develop "Green" Steel
University of Pittsburgh
Pittsburgh, Pennsylvania
Purpose: Sustainability Research
Please note that the copyright for this profile is retained by the institution.
Reprinted with permission from University of Pittsburgh's Researchreview article by John Fedele "Getting the lead out: Pitt Researchers Develop Lead-Free Steel"
They call it "green" steel, and it could be one of the most important innovations in steel in the last 30 years.
Pitt researchers Anthony J. DeArdo and C. Isaac Garcia, professors of materials science and engineering, have developed a lead-free alternative to free machining steel, called 12L14 steel in the industry, which is not only more environmentally friendly, but is more machinable than leaded steel.
Steel manufacturers add lead, which is highly toxic, to steel when producing steel bars to make them easier to cut and shape. The steel bars are sent to machine shops, where machinists create screws, cogs, flywheels and other parts for machines. The most common use for the steel is in automobile parts.
"As the University of Pittsburgh seeks to advance fundamental knowledge through research, it develops technology 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 is the latest example of the key role which Pitt plays in contributing to the economic vitality of the communities we serve," said Pitt Chancellor Mark A. Nordenberg.
A patent for the new lead-free steel was filed by the University of Pittsburgh and it will soon issue. The University, through the Office of Technology Management, created a 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; Saarstahl Steel, AG, of Volklingen, Germany; Laurel Steel, a Division of Harris Steel Ltd., of Ontario, Canada; United Alloys & Steel Corporation, of Buffalo, NY; MacSteel, a Division of Quanex Corporation, of Fort Smith, Arkansas; and Curtis Niagra, LLC. USS/KOBE Steel Company has been supporting the research at the university, and has the option of joining the consortium by July 31. Members of the consortium have helped finance the research at Pitt for the past four years.
The work was conducted by DeArdo and Garcia through the Basic Metals Processing Research Institute (BAMPRI), which is affiliated with the School of Engineering's Department of Materials Science and Engineering.
A test of the final product, completed recently at USS/Kobe Steel Company, found that a 220-ton heat (full scale production) of the new steel performed as well as the 12L14 grade steel. 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, director of technology management, estimates that the "green" steel has the potential to save manufacturers as much as 20 percent per ton in environmental costs and machining.
"Ever since governments began asking steel manufacturers to reduce their use of lead, researchers have been trying to come up with alternatives," said DeArdo. For example, Boni pointed out that Germany recently mandated that its manufacturers use lead-free alternatives whenever possible.
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 tin/steel ratio DeArdo and Garcia settled on not only performs as well as the leaded steel, but is easier to machine, which should save machine shops labor costs, according to DeArdo.
And that makes the new steel "green" in more ways than one.
John Fedele
Office of News and Information
University of Pittsburgh
jfedele@pitt.edu
This document was last modified on 02/20/2002 10:43:03 AM
© 2005 Second Nature, Inc.
