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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
|This report is an archived publication and may contain dated technical, contact, and link information|
|Publication Number: FHWA-HRT-11-062 Date: November 2011|
Publication Number: FHWA-HRT-11-062
Date: November 2011
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Plate girder bridges are usually fabricated from painted carbon steels or unpainted weathering steels. Weathering steels, including the modern high-performance steels, offer the lowest life-cycle cost (LCC) over the design life of the bridge because ongoing maintenance due to steel deterioration is not necessary in most service environments. However, in areas where a bridge is subject to high time-of-wetness or high chloride exposures (i.e., coastal areas or areas where large quantities of deicing salt are used), weathering steels are not effective because the protective patina does not develop, and the steel has a high corrosion rate. In these conditions, structural stainless steel ASTM A1010 (UNS S41003) provides sufficient corrosion protection so that painting is not necessary, and the bridge structure is maintenance-free during its design life.(1) The initial cost of stainless steel is more than twice the cost of carbon or weathering steel. Reducing the cost of stainless steel would improve the LCC of bridges in severe corrosion service conditions. This study was undertaken to identify steels with lower potential cost than ASTM A1010 that could be candidates for bridge construction while still providing low corrosion rates.
Jorge E. Pagán-Ortiz
Director, Office of Infrastructure
Research and Development
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Technical Report Documentation Page
|1. Report No.
|2. Government Accession No.||3 Recipient's Catalog No.|
|4. Title and Subtitle
Improved Corrosion-Resistant Steel for Highway Bridge Construction
5. Report Date
|6. Performing Organization Code|
Fred B. Fletcher
8. Performing Organization Report No.
9. Performing Organization Name and Address
ArcelorMittal Global R&D-East Chicago
10. Work Unit No. (TRAIS)
11. Contract or Grant No.
|12. Sponsoring Agency Name and Address
Office of Infrastructure Research and Development
|13. Type of Report and Period Covered
14. Sponsoring Agency Code
15. Supplementary Notes
The Contracting Officer's Technical Representative (COTR) was Yash Paul Virmani, HRDI-60.
Alloy steels with 9, 7, and 5 percent chromium (Cr) were designed to reduce the cost of ASTM A1010 steel containing 11 percent Cr. Additions of 2 percent silicon (Si) and/or 2 percent aluminum (Al) were made. The experimental steels could be heat treated to achieve the strength needed for bridges. However, only the ASTM A1010 steel exhibited sufficient impact toughness to be a candidate for bridge construction. The mechanical properties of the experimental steels are not suitable for bridge construction, although they are substantially more corrosion resistant than the conventional weathering steel, ASTM A588.
When studied in the laboratory using cyclic corrosion tests, all of the steels exhibited a relatively linear rate of corrosion with increasing cycle number. As the Cr content decreased, the corrosion rate increased. The corrosion rate of the ASTM A1010 steel was one-tenth of the rate of the ASTM A588 steel. Si was detrimental to corrosion resistance, while Al was beneficial. The corrosion behavior was not a function of the steel yield strength. As the cyclic corrosion cycles increased, the proportion of oxyhydroxide corrosion product akaganeite declined and was replaced by maghemite, goethite, and lepidocrocite. However, the 11 percent Cr steels contained significantly less maghemite than the steels with lower Cr content.
The 9 percent Cr, 7 percent Cr plus 2 percent Si, and 7 percent Cr plus 2 percent Al steels were exposed for 1 year on the heavily salted Moore Drive Bridge in Rochester, NY. Their corrosion rates were approximately one-half the rate of ASTM A588 weathering steel. The rust composition was similar for all three experimental steels.
Life-cycle cost analyses examined the benefits of using a maintenance-free corrosion-resistant steel instead of regularly repainting a conventional steel bridge girder. By the 20th year of service, the probability is over 90 percent that the ASTM A1010 steel girder is less expensive. After 40 years, it becomes certain that the ASTM A1010 steel girder is cheaper than the painted conventional steel.
|17. Key Words
Stainless steel, Bridges, Corrosion resistance, Atmospheric corrosion, Steel, Cyclic corrosion test, Maghemite, A1010
|18. Distribution Statement
No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161.
19. Security Classification
20. Security Classification
21. No. of Pages
|Form DOT F 1700.7||Reproduction of completed page authorized|
|CCT||Cyclic corrosion test|
|DA||Rust from downward-facing coupon surface|
|DAU||Rust from under the course rust from the downward-facing surface|
|DT||Rust from the top part of the downward-facing surface|
|EUL YS||Elongation under load yield strength|
|HBW||Brinell Hardness number|
|LCVN||Longitudinal Charpy V-notch|
|mil||One-thousandth of an inch|
|mpy||mil per year|
|RA||Reduction of area|
|SAE||Society of Automotive Engineers|
|UA||Rust from upward-facing coupon surface|
|UAF||Fine rust from all upward-facing surfaces|
|UAU||Rust from under the course rust from the upward-facing surface|
|UB||Rust from bottom part of the upward-facing surface|
|UT||Rust from top part of the upward-facing surface|
|USGS||United States Geological Survey|
|va||Very adherent rust|
|α||Greek letter alpha|
|β||Greek letter beta|
|γ||Greek letter gamma|
|CA1010||Cost of the ASTM A1010 steel girder|
|Cconv||Cost of the conventional painted steel girder|
|h0||Original height of Charpy hammer|
|h||Final height of Charpy hammer after impacting test specimen|
|n-value||Strain hardening coefficient in a tensile test|
|R2||Coefficient of determination|
|t||Paint application time|
|v||Discount rate of money|