Keywords
Localized corrosion
Spot welding
Intercritical zone
How to Cite
Abstract
Galvanized steel is widely used and the electropump welding process is a method used for its assembly. The main objective is to evaluate of spot welding on sheets steel AISI 1015 galvanized. Welds have three distinct areas, the fusion zone (ZF), the heat affected zone (HAZ), consisting of a coarse grain zone (CGZ) and the intercritical region (ICZ); and base material (BM). By comparing the microstructures of welded sheets with different coatings it was found that the HAZ increase in size with increasing coating thickness, this is attributed to the coating decreases heat transfer, which makes the cooling rate decreases and increase in size of the HAZ. The corrosion present was localized corrosion. In the electrochemical test, the zinc ions form corrosion products Zn(OH)2 from the interaction with the sulfate and chloride ions. It is concluded that the thickness of the coating influences the microstructure of the welds, affecting the size and morphology of the areas and the zinc coating when in contact with the acidified solution, in a short time, forms a synergistic inhibiting effect.
Keywords: Steel galvanized, localized corrosion, spot welding, intercritical zone.
References
[1]M. Delgado, “Soldabilidad de aceros IF y HSLA galvanizados para aplicación automotrices”, Universidad Autónoma de Nueva León. Facultad de Ingeniería Mecánica y Eléctrica. 2014.
[2] K. Randall Chan, “Weldability and Degradation Study of Coated Electrodes for Resistance Spot Welding”, University of Waterloo. 2005.
[3] ASTM, “Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products”. A-123, USA, 2001.
[4] AWS, “Recommended Practices for Resistance Welding”, C1.1 USA, 2012.
[5]UNE, ISO 14329 y 10447, “Ensayos Destructivos de Soldadura”, Madrid, España, 2004.
[6]ASME, “Norma de soldadura fuerte”, Sección VI, USA, 2010.
[7] ASTM, “Standard Guide for Preparation of Metallographic Specimens”, E-3, USA, 2001.
[8] COVENIN, “Materiales Metálicos: Ensayo de Dureza Vickers”, 616-89, Caracas, Venezuela, 1989.
[9] ASTM, “Standard Practice for Laboratory Inmersion Corrosion Testing of Metals”, G-31, USA, 2001.
[10] ASTM, “Standard Reference Test Method for Making Potentiostatic and Potentiodynamic Anodic Polarization Measurements”, G-5, USA, 2001.
[11]ASM Metal handbook, “Welding, Brazing, And Soldering”, Vol. VI, p. 326, USA, 2006.
[12]F. Rauchle and M.I. Díaz, “Inhibición de la corrosión”, Revista de Química de la Pontificia Universidad Católica del Perú Vol. IV. N° l, 1990.
[13]D. Ballesteros, A. Sandoval, H. Estupiñan, D. Sierra and L. Fajardo, “Corrosión de acero galvanizado en un ambiente que contiene cloruros y sulfatos mediante técnicas electroquímicas”, Informador Técnico, Colombia, 79(2), pp. 127-136. 2015.
[14]ASM Metal Handbook, “Corrosion Fundamentals, Testing and Protection”, Vol. 13A, pp. 2019, 2306 y 2325, USA, 1987.