ENG  Vol.5 No.8 , August 2013
Effect of Zinc Galvanization on the Microstructure and Fracture Behavior of Low and Medium Carbon Structural Steels
Microstructure and fracture behavior of ASTM 572 Grade 65 steels used for wind tower applications have been studied. Steels of two carbon level chemistries designed for this grade were used in the study. Fracture toughness of the steels was studied using 3-point bend test on samples coated with zinc and not coated with zinc. Lower carbon steel showed higher resistance to fracture than medium carbon steel after zinc galvanization. SEM study suggests that zinc and zinc bath additives that migrated to crack tips are responsible for the loss in ductility. The phenomenon of Liquid Metal Embrittlement (LME) is suggested to have taken place. Zinc bath additives traced at crack zones are suggested to have migrated at the zinc galvanizing temperatures.

Cite this paper
I. Okafor, R. O’Malley, K. Prayakarao and H. Aglan, "Effect of Zinc Galvanization on the Microstructure and Fracture Behavior of Low and Medium Carbon Structural Steels," Engineering, Vol. 5 No. 8, 2013, pp. 656-666. doi: 10.4236/eng.2013.58079.

[1]   ASTM Standard A123/A123M-09, “Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel,” ASTM International, West Conshohocken, 2009. doi:10.1520/A0123_A0123M-09

[2]   ASTM Standard A143/A143M-07, “Safeguarding against Embrittlement of Hot-Dip Galvanized Structural Steel Products and Procedure for Detecting Embrittlement,” ASTM International, West Conshohocken, 2007. doi:10.1520/A0143_A0143M-07

[3]   ASTM Standard A385/A385M-11, “Standard Practice for Providing High-Quality Zinc Coatings (Hot-Dip),” ASTM International, West Conshohocken, 2011. doi:10.1520/A0385_A0385M-11

[4]   P. Gordon, “Environmental Sensitivity of Structural Metals: Liquid Metal Embrittlement,” Project Themis, Illinois Institute of Technology, Chicago, 1970.

[5]   R. E. Clegg and D. R. H. Jones, “Liquid Metal Embrittlement in Failure Analysis,” Material Science, Vol. 27, No. 5, 1992. doi:10.1007/BF00726455

[6]   G. Poag and J. Zervoudis, “Influence of Various Parameters on Steel Cracking during Galvanizing,” AGA Tech Forum, Kansas City, October 2003.

[7]   D. G. Kolman, “Liquid Metal Induced Embrittlement,” In: ASM Handbook Vol. 13A, Corrosion: Fundamentals, Testing, and Protection, ASM International, Metals Park, 2003, pp. 381-392.

[8]   R. Steiner, “Properties and Selection: Irons, Steels and High Performance Alloys,” 10th Edition, ASM International, Metals Park, p. 717.

[9]   J. Mandela, “Liquid Metal Embrittlement of Steel with Galvanized Coatings,” Materials Science and Engineering, Vol. 35, 2012.

[10]   V. V. Popovich, “Mechanisms of Liquid Metal Embrittlement,” Material Science, Vol. 15, No. 5, 1980.

[11]   International Lead Zinc Research Organization, “Galvanizing Characteristics of Structural Steel and Their Weldments,” BNF Metals Technology Centre, Wantage, 1975.

[12]   G. Poag and J. Zervoudis, “Influence of Various Parameters on Steel Cracking during Galvanizing,” AGA TechForum, Kansas, 2003.

[13]   T. J. Kinstler, “Research and Update on Galvanized Reinforcing Steel,” Industrial Galvanizers America, Midlothian.

[14]   T. Kinstler, “Cope Cracking Report 5/3/194,” Metalplate Galvanizing Inc., Limited and Internal Circulation.

[15]   T. J. Kinstler, “Current Knowledge of the Cracking of Steels during Galvanizaton,” GalvaScience LLC, AISC, 2005.

[16]   M. Vermeersch, W. De Waele and N. Van Caenegem, “LME Susceptibility of Galvanized Welded Structures of High Strength Steels,” Sustainable Construction and Design, 2001, pp. 442-447.

[17]   W. J. Judd and S. W. Wen, “Failure Mechanisms during Galvanization,” 2008.

[18]   T. Kinstler, “Status Report on the Cracking of Copes in Galvanized Structural Beams,” Metalplate Galvanizing, Inc., Limited and Internal Circulation.

[19]   T. Kinstler, “Cope Cracking Progress Report, 2/1/92 (rev 1),” Metalplate Galvanizing, Inc., Limited and Internal Circulation.

[20]   Project ZM-396, “Control of Cracking in Galvanized Structurals,” Serial Reports Produced by ANMET, Metals Technology Laboratories, Ottawa, 1993-1997.

[21]   J. Robinson, “Predicting the In-Ground Performance of Galvanized Steel,” Mount Townsend Solutions Pty Ltd., March 2005.

[22]   H. E. Townsend, “Effects of Zinc Coatings on the Stress Corrosion Cracking and Hydrogen Embrittlement of Low-Alloy Steel,” Metallurgical and Materials Transactions, Vol. 6A, 1975, pp. 877-883.

[23]   S. R. Yeomans, “Galvanized Steel Reinforcement in Concrete: An Overview,” In: S. R. Yeomans, Ed., Galvanized Steel Reinforcement in Concrete, Elsevier, 2004, p. 320.

[24]   H. Abe, et al., “Study of HAZ Cracking of Hot-Dip Galvanizing Steel Bridge,” IIWDoc. IX-1974-94.

[25]   K. Priestley and J. Carpenter, “Liquid Metal Assisted Cracking of Galvanized Steel Work,” SCOSS—Standing Committee on Structural Safety, London, September 2005.

[26]   W. K. Boyd and W. S. Hyler, “Factors Affecting Environmental Performance of High Strength Bolts,” Journal of the Structural Division—ASCE, Vol. 99, 1973, pp. 1577-1588.

[27]   G. Sedlacek, et al., “On the Reliable Application of Hot Dip Zinc-Coated Steel Beams,” Stahlbau, Vol. 73, 2004, pp. 427-437.

[28]   E. Nicholas, Y. Durandet and L. Strezov, “Dynamic Reactive Wetting and Its Role in Hot Dip Coating,” Metallurgical and Materials Transactions, Vol. 31B, 2000, p. 1069.

[29]   L. S. Darken, “Diffusion of Carbon in Austenite with a Discontinuity of Composition,” Transactions on AIME, Vol. 180, 1949, pp. 430-438.

[30]   J. Agren, Scandinavian Journal of Metallurgy, Vol. 11, 1982, pp. 3-8.

[31]   A. R. Mader, “The Metallurgy of Zinc-coated Steel,” Progress in Materials Science, Vol. 45, 2000, p. 271.

[32]   M. Urednicek and J. S. Kirkaldy, “Mechanism of Iron Attack Inhibition Arising from Additions of Aluminum to Liquid Zn (Fe) during Galvanizing,” Zeitschrift für Metallkunde, Vol. 64, 1987, p. 649.