Materials Performance

NOV 2014

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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62 NOVEMBER 2014 MATERIALS PERFORMANCE NACE INTERNATIONAL: VOL. 53, NO. 11 MATERIALS SELECTION & DESIGN caused white rust formation. Rainwater leaking into the splay chambers and inef- fe ctive d ehumi dif ication caused more white rust and even some red rust to form, which then flowed downward on the HDG surfaces of the PWS anchor rod assemblies in the splay chambers (Figure 6). For a steel bridge with a 150-year design life, critical components must be protected f r o m c o r r o si o n d a m a g e e v e n d u r i n g construction. Conclusions Laboratory and field performance data are not available in the literature on HE fail- ures of 3- to 4-in diameter ASTM A354 Grade BD rods that have M-shaped hardness tra- verse profiles, post heat treatment roll- formed threads, and a HDG coating. Some anchor rods on the SAS span might fail due to EHE during service; and some are neither repairable nor replace- able. The same is true of the PWS cable. Its wires are vulnerable to atmospheric corrosion damage in the splay chambers and other locations if dehumidification is ineffective. A steel bridge with a 150-year design life over seawater would require a more thorough evalua- tion of materials performance (su ch a s su sc e pti bi lity to HE cracking ) and corrosion engi- neering (such as dehumidifica- t i o n n e e d s) t h a n w o u l d b e required for a 75-year life bridge. References 1 M. Nader, B. Maroney, "One-of-a- Kind Design, The New San Fran- cisco-Oakland Bay Bridge Eastern Span," Structure (October 2007), pp. 30-35. 2 ASTM A354 "Standard Specifica- tion for Quenched and Tempered Alloy, Steel Bolts, Studs, and Other Externally Threaded Fasteners" (West Conshohocken, PA: ASTM International). 3 ASTM A709/A709M " Standard Specification for Carbon and High- Strength L ow-Alloy Str uctural Steel Shapes, Pipes, and Bars and Quenched-and-Tempered Alloy Structural Steel Plates for Bridges" 8 Y. Chung, L.K. Thomas, "High Strength Steel Anchor Ro d P robl ems on th e Ne w Bay Bridge, Rev. 1," November 12, 2013, http:// docdroid.net/dxzl (Sept. 10, 2014). 9 H.E. Townsend, "Effects of Zinc Coating on the Stress Corrosion Cracking and Hydrogen Embrittlement of Low Alloy Steel," Metallur- gical Transactions A 6A (1975), pp. 877-883. 10 A.R . Kephart, "Optimum Thread Rolling Process that Improves SC C Resistance," P.M. Toor, J. Barraon, eds., Structural Integrity of Fasteners Including the Effects of Environ- ments and Stress Corrosion Cracking (West Conshohocken , PA: ASTM International , 2007), p. 31. 11 Y. Chung, L.K. Thomas, "Main Concerns and Resolutions for Fracture-Critical Anchor Rods on the New Bay Bridge," December 30, 2013, http://docdroid .net/e0xi (Sept. 10, 2014). 12 "Steel Bridge Handbook, Loads and Load Combinations," Federal Highway Adminis- tration, FHWA-IF-12-052-Vol. 7, Nov. 2012. 13 "AASHTO LFRD Bridge Design Specifica- tions," 6th ed ., American Association of State Highway and Transportation Officials, LRFDUS-6, 2012. 14 "Self-Anchored Suspension Bridge Design Criteria," Caltrans/Division of Structures, Contract 59A0040, July 15, 2002, http:// www.dot.ca.gov/baybridge/a354report/F1_ Self-Anchored_Suspension_Bridge_Design_ Criteria_100_percent_submittal.pdf (Sept. 10, 2014). This article is based on the data released by Caltrans. YUN CHUNG, e-mail: yunchung2@comcast. net, retired as a materials engineering specialist in 1995 from Bechtel Corp. in San Francisco, California and was a metal- lurgy consultant until 2013 to Anamet, Inc., Hayward, California. While at Bechtel, Chung provided materials engineering services on materials selection, fracture penetration, ASME/AWS welding proce- dures, and corrosion control for engineer- ing/construction. He has a B.S. degree in mechanical engineering, B.S. and M.S. degrees in metallurgy, and is a 36-year member of NACE International. FIGURE 6 (a) PWS-socket-anchor rod assemblies. (b) White and red rust on PWS-socket juncture. Corrosion of PWR anchor assemblies. (West Consho hocken, PA: ASTM Interna- tional). 4 ASTM A307-12, "Standard Specification for Carbon Steel Bolts, Studs, and Threaded Rod 60 000 PSI Tensile Strength" (West Con- shohocken, PA: ASTM). 5 ASTM A325-10e1, "Standard Specification for Structural Bolts, Steel , Heat Treated , 120/105 k si Minimum Tensile Strength" (West Conshohocken, PA: ASTM). 6 ASTM A490–12, "Standard Specification for Structural Bolts, Alloy Steel, Heat Treated, 150 ksi Minimum Tensile Strength" (West Conshohocken, PA: ASTM). 7 H.H. Johnson, "Keynote Lecture, Overview on Hydrogen D egradation Ph enom ena ," R . Gibala, R .F. Hehemann, eds., Hydrogen Embrittlement and Stress Corrosion Cracking (Materials Park, OH: ASM International , 1984), pp. 3-27. (a) (b)

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