The dependence of cavity-growth rate on stress triaxiality

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12/29/04

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The Dependence of Cavity-Growth Rate on Stress Triaxiality P.D. NICOLAOU, S.L. SEMIATIN, and A.K. GHOSH

Fig. 4—C1s and Ca2p high-resolution XPS spectra obtained on the surface of pure Zn and galvanneal coatings.

on the outer surface of the coating obtained by hot galvanization, in which the Fe-Zn alloy forms only a thin layer close to the steel surface followed by a zinc layer of much greater thickness (schematic picture in Figure 3(c)). In the case of the galvanneal coating, the growth of the Fe-Zn alloy would push the contamination toward the outer surface of the coating (Figure 3(d)), while on the galvanized coating, it would remain at the Fe-Zn alloy/Zn interface (Figure 3(d)), and thus be impossible to detect. This phenomenon is somewhat similar to other cases reported in the literature, e.g., 1. that iron oxide films present on the steel surface are ejected during galvanization into the zinc melt, 2. that these films are incorporated in the Fe-Zn alloy/Zn interface,[13] and 3. that in Zn(Al) baths, the Fe2Al5 inhibiting layer is pushed into the melt during the formation of the galvanized coating.[14]

The authors acknowledge the European support of this research (ECSC Projects Nos. 7210-PR-119 and 7210-PR-121). REFERENCES 1. I. Hertveldt, B.C. De Cooman, and S. Claessens: Metall. Mater. Trans. A, 2000, vol. 31A, pp. 1225-32. 2. A.R. Marder: Progr. Mater. Sci., 2000, vol. 45, pp. 191-271. 3. S. Feliu, Jr. and M.L. Pérez-Revenga: Metall. Mater. Trans. A, 2004, vol. 35A, pp. 0000-00. 4. A. Henion: ECSC Project No. 7210-PR/119, Final Report, ECSC, Luxembourg, 2002. 5. G. Kurbatov, E. Darque-Ceretti, and M. Aucoutier: Surf. Interface Anal., 1993, vol. 20, pp. 402-06. 6. D.R. Cousens, B.J. Wood, J.Q. Wang, and A. Atrens: Surf. Interface Anal., 2000, vol. 29, pp. 23-32. 7. Th. Mayer: Appl. Surf. Sci., 2001, vol. 179, p. 257. 8. U. Clofsson and S. Didzar: Wear, 1998, vol. 215, p. 156. 9. E.J. Ekanem, J.A. Lori, and S.A. Thomas: Talanta, 1997, vol. 44, p. 2103. 10. P.E. Lafargue, N. Chaoui, E. Millon, J.F. Muller, H. Derule, and A. Popandenec: Surf. Coating Technol., 1998, vol. 106, p. 268. 11. P. Gouérec, M. Savy, and J. Riga: Electrochim. Acta., 1998, vol. 43, p. 743. 12. B. Chatelain and V. Leroy: La Rev. Metall. CIT, 1998, vol. 6, p. 331. 13. C.E. Jordan and A.R. Marder: Metal. Mater. Trans. B, 1998, vol. 29B, pp. 479-84. 14. M. Guttmann: Mater. Sci. Forum, 1994, vols. 155–156, p. 527. METALLURGICAL AND MATERIALS TRANSACTIONS A

The hot working of metals is often accompanied by the formation of internal cavities. The cavitation process can be divided into three distinct, but usually overlapping, stages—nucleation, growth, and coalescence. Moreover, the extent of cavitation (e.g., cavity size and volume fraction) often exhibits a strong dependence on alloy composition and microstructure as well as on the imposed processing conditions (temperature, strain, strain rate, stress state). The development of an understanding of cavitation is important because it may limit hot workability a

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