Study on the Failure Mechanism of Enamel Coatings in HAZ

Abstract:

Because the enamel coatings has excellent ageing resistance and anti-corrosion performance, the service life of pipeline with enamel coatings as protective layer can be increased remarkably comparing with the ones with organic coatings. But when the pipeline is welded, the high temperature of welding arc will do harm to the bonding strength of the enamel coating and the base metal because of the differences of thermo-physical properties between them. In order to study the failure mechanism of enamel coating in the heat affected zone, the stress changing process of enamel/steel was studied through numerical simulation and the interface of enamel/steel was studied by welding thermal simulation technology. The results show that the weakness parts of the welded joints are the imperfect normalized zone and overheated zone. In the imperfect normalized zone, the micro-cracks generate at the interface of enamel/steel because high stress occurred and some coatings fused incompletely because of short staying time at high temperature that induced micro-cracks in the enamel coating under high welding stress, so it was one of the dangerous zones of HAZ. Because high tensile stress formed during cooling that was dangerous to the brittle enamel coating, the bond layer of enamel/steel was damaged by high temperature of welding and the pores generated at the interface of enamel/steel, the coatings of overheated zone could be pulled off from the base metal easily that caused the steel exposed to the corrosion medium directly without the protection of enamel coating, so it was another dangerous zone of HAZ. Keywords: enamel coating; numerical simulation; welding thermal simulation; failure mechanism; HAZ

• Periodical: Materials Science Forum (Volumes 704-705)
• Pages: 700-705
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.704-705.700
• Online since: December 2011
• Authors: Han Tao, Wang Yong, Wei Liu
• Keywords: Enamel Coating, Failure Mechanism, Heat Affected Zone (HAZ), Numerical Simulation, Welding Thermal Simulation

References

[1] K.R. Trethewey, D.R. Roberget: British Corrosion Journal Vol. 30 (1995), p.192.

[2] Shao Guixian, Gou Wenbin and Wen Ruichang: Enamel (Light industry press, Beijing 1983).

[3] Christian Schlegel, Koen Lips and Frits Lamote: Vitreous Enameller Vol. 51(2000) , p.125.

[4] T. Iwasaki and H. Miura: J. Mater. Res. Vol. 16(2001), p.1789.

[5] E.A. Yastenkor, V.P. Svechkarev, E.A. Perova, et al.: Glass and ceramics Vol. 59(2002), p.322.

[6] Leila Samiee, Hossein Sarpoolaky, Alireza Mirhabibi: Mater. Sci. & Eng.: A, Vol. 458(2007), p.88.

[7] Deyou Zheng, Shenglong Zhu and Fuhui Wang: Surface and coatings technology Vol. 49(2006), p.5931.

[8] M.T. Kim, S.Y. Chang, O.Y. Oh, J.B. Won, H.W. Park: Engineering Failure Analysis Vol. 14(2007), p.686.

[9] Wang Zhi-ping, Dong Zu-jue, Li Li and Han Song: Transactions of the China welding institution, Vol. 20(1999), p.278.

[10] M. Laribi, N. Mesrati, A.B. Vannes and D. Treheux: Surface and coatings technology, Vol. 43(2003), p.206.

DOI: 10.1016/s0257-8972(02)00818-6

[11] Wang Hong, Zhang Kun and Chen Guang-nan: Heat treatment of metals Vol. 26(2001), p.44.

[12] Wang Hong, Zhang Kun and Chen Guang-nan: Heat treatment of metals Vol. 26(2001), p.17.

[13] Zhang Xiancheng, Xu Binshi, Wang Haidou and Wu Yixiong: Chinese journal of mechanical engineering Vol. 42(2006), p.18.

[14] Mao Weiguo and Zhou Yichun: Natural science journal of Xiangtan University Vol. 25(2003), p.39.

[15] X. K. Zhu, Y. J. Chao: Journal of Materials Processing Technology Vol. 146(2004), p.263.

[16] H.J. Zhang, G.J. Zhang, C.B. Cai, H.M. Gao, L. Wu: Materials Science and Engineering: A Vol. 499(2009), p.309.

[17] Peng-Hsiang Chang and Tso-Liang Teng: Computational Materials Science Vol. 29(2004), p.511.

[18] Goldak John, Chakravarti Aditya, Bibby Malcolm. Metallurgical transactions B (Process metallurgy) Vol. 15B (1984), p.299.

[19] Tailor G A, Hughes M, Pericleous K: Modeling of casting, welding and advanced colidification process IX, (San Diego 2000).

[20] Help of SYSWELD2008. ESI Ltd.

[21] Zhang Wenyue: Welding metallurgy (Mechanical industry publishing company, Beijing 1993).