Further Development and Marketing of Low-Cost, High Performance Steels for Infrastructure Applications

1. INTRODUCTION/ PROGRESS AND CURRENT STATUS We witnessed significant progress in the past year in our marketing efforts and in the development of new low-cost high-performance steels. Our SAFTEA-LU Year 5 efforts will build upon this success. In addition to continuing our outreach and marketing activities with steel companies, state and public transit agencies, we will collaborate with steel companies to develop even lower-cost commercial steels with improved mechanical properties and weathering resistance. Further, we will address the FHWA grand challenge: developing "super" weathering steels, especially for operating in salt environments, with ASTM G101 corrosion index of 9.0. Such steels will sustain only one-fifth the corrosion loss of existing weathering steels such as A588. Results obtained in the past year have shown us the right direction, and we are tantalizingly close to reaching this goal. The following summarizes our progress for the SAFTEA-LU Year 4 project: (a) With the support of ITI over the past few years, we developed and thoroughly tested a series of high-performance steels for infrastructure applications. One steel, A710B, was produced in the plate form and was used to fabricate welded girders for a large bridge in Lake Villa, Illinois in 2006. This steel is the most corrosion-resistant structural steel on the market today. As a result, the bridge was not painted, resulting in more than $300,000 in savings. Our periodic inspections of this bridge indicate that the steel weathers uniformly and that a very hard and highly adherent protective oxide coating has formed on the steel surface. In year 4, we continued marketing of this steel. In 2009, IDOT approved the construction of a new bridge on Dixie Highway in Flossmoor, Illinois and requested us to develop a less expensive variant of A710B. We succeeded with a "lean" version or A710B (labeled as A710B-L) by reducing the amounts of Cu and Ni in the steel. Its mechanical and fracture-resistant properties significantly exceed the requirements for bridge steels. Steel Dynamics produced this steel in 2010 in the form of largeflange I-beams. The use of I-beams led to the elimination of welding, further reducing the construction cost. The Dixie Highway Bridge was finished in November 2010 (Figure 1). Note that A709 high-performance bridge steel, the competitor to our bridge steels, could not be produced as I-beams because it requires special thermo-mechanical processing to achieve its properties. Our steels do not need heat treatment; they are just hot-rolled and air-cooled. (b) Sponsored by FHWA, we developed a knowledge-based theoretical approach to the design of "super" weathering steels. Based on this approach, we made the first attempt to designing such steels. A 50-kg laboratory prototype was produced (labeled as A710B-Ti-P). The mechanical properties are excellent: yield strength = 57 ksi, and elongation to failure ~ 30%, Charpy absorbed energy at 25ºC = 94 ft-lbs. Accelerated weathering tests performed at the Kentucky Transportation Center demonstrated that this steel exhibits significantly less corrosion loss than steels currently used in bridges, including A588W weathering steel and our original A710 Grade B steel (Figure 2). 2 Figure 1. Dixie Highway Bridge completed in 2010 using large-flange A710B-L I-beams Figure 2. Accelerated weathering test results (ASTM G85 annex A) performed at the Kentucky Transportation Center (c) We visited Nucor Steel Company in Decatur, AL and presented our work on strengthening and toughening of steels using nanosized copper precipitates. Subsequent discussion led Nucor to use our concept to improve the strength and toughness of their coiled sheet steels. Nucor invested more than $100,000 to develop these new steels (see attached letter). In accordance with our recommendations, Nucor produced two 170-ton commercial heats of the steel for structural support rails for truck frames, with increased yield and ultimate tensile strengths by about 15%, from 71 to 82 ksi and from 85 to 97 ksi respectively. The absorbed fracture energy of the steel was very high, more than 150 ft-lbs at -20°F in small, ¾-sized, Charpy specimens. The ASTM G101 corrosion index for the new Northwestern-modified Nucor steel increases from about 4.2 to 6.2. According to Table 1, the Northwestern-modified Nucor steel is more corrosion-resistant than A588 and A606 (used for signs, sign structures, light poles and other highway structures). This means that for example, under certain standard weathering conditions, the new Northwestern-modified Nucor steel will sustain only 70% of the corrosion loss of A606. 0.00 0.05 0.10 0.15 0.20 A572 A588 50W A710B A710B-Ti-P Corrosion Loss, g/cm2 VVV 3 Table 1. ASTM G101 Corrosion Index for Selected Steels 2. OBJECTIVES OF THE PROPOSED RESEARCH FOR FY2012 This proposal addresses the goal of National Strategy for Surface Transportation Research to improve highway structures by enhanced materials, in particular by design and implementation of new, drastically improved steels with respect to strength, low-temperaturefracture toughness, weldability, and weatherability. Therefore, our objectives for FY2012 are to develop low-cost, high-performance steels (modifications of A710B) and to market these steels for infrastructure and other industrial applications. Research and commercialization activities will include (1) development of low-cost, high-performance alternatives to A588 weathering steel for bridges and A606 steel for highway structures such as signs, signal structures, and light poles; (2) pushing the corrosion performance of our "super" weathering steel for operation under high-salt environments; (3) monitoring the weathering performance of two Illinois bridges built with our steels (Lake Villa and Dixie Highway); (4) marketing and participation in the construction of new bridges in Illinois and other states; (5) working with companies in the commercialization of our steels for other than bridge applications; and (6) presentations in professional conferences, visits to steel companies and consumers to further promote the steels developed with ITI funding for infrastructure and other applications. The main deliverables in FY 2012 are: * New low-cost, high-performance steels with mechanical and corrosion performance superior to those of A588, current weathering steel used in bridges and A606, current steel used in highway structures such as signs, signal structures, and light poles; * New P-alloy steel with significantly enhanced corrosion performance with good lowtemperature fracture toughness; * New bridge/bridges in Illinois and other states built with A710 Grade B steel or its lowercost modifications; * Disseminations of results via presentations in conferences, meetings with steel companies and consumers, and publications in journals and proceedings. In addition, we are developing steels for infrastructure applications with better weathering properties. A few years ago, Federal Highway Administration expressed interest in the development of a "super" weathering steel for bridges in highly corrosive chloride-laden environments. We were sponsored by FHWA to develop a knowledge-based theoretical design of such a "super" weathering steel. We found that some elements that were not used in weathering steels in the past could significantly boost corrosion resistance of steels. We designed a new steel based on the A710 Grade B steel composition with addition of more phosphorous and titanium. A laboratory steel heat was produced and is being tested. The steel is strong and very ductile. Preliminary laboratory accelerated tests indicated the superior corrosion resistance of the newly developed steel over our original A710 Grade B and the currently used in bridges A709 HPS70W steel. Since the market for steels for infrastructure applications such as bridg


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  • Status: Completed
  • Contract Numbers:

    610 4742000 60020782


  • Sponsor Organizations:

    Infrastructure Technology Institute (ITI)

    Northwestern University
    L260 Technological Institute, 2145 Sheridan Road
    Evanston, IL  USA  60208-3109
  • Principal Investigators:

    Chung, Yip-Wah

    Fine, Morris

    Vaynman, Semyon

  • Start Date: 20080307
  • Actual Completion Date: 20120831
  • Source Data: RiP Project 16779

Subject/Index Terms

Filing Info

  • Accession Number: 01468446
  • Record Type: Research project
  • Source Agency: Infrastructure Technology Institute (ITI)
  • Contract Numbers: 610 4742000 60020782, A226
  • Files: UTC, RiP
  • Created Date: Jan 3 2013 3:51PM