Journal of Brilliant Engineering 3 (2021) 22-26 www.acapublishing.com *Corresponding Author: ezirmik@atauni.edu.tr (K.V.Ezirmik Orcid: 0000-0001-9286-6925) Received 01 Apr 2021 Revised 02 Apr 2021 Accepted 02 Apr 2021 Brilliant Enginering 3 (2021) 22-26 2687-5195 © 2019 ACA Publishing. All rights reserved. https://doi.org/10.36937/ben.2021.003.005 22 Research Article Corrosion and High Temperature Oxidation Behavior of Structural Steels Coated with Aluminum Alloys Kadri Vefa Ezirmik * , 1 , Furkan Kalan 2 1 Ataturk University, Department of Metallurgical and Materials Engineering, Erzurum, Turkey 2 Ataturk University, Graduate School of Natural and Applied Sciences, Erzurum, Turkey Keywords Abstract Hot dip, Aluminum coatings, Corrosion, High temperature oxidation, AA1050, AA2024, AA5083. Structural steels are among the most widely used materials in today's industry. Various surface coating processes are used to protect structural steels from corrosion in atmospheric or aggressive environments. The most commonly used method is the galvanizing process based on forming zinc coating on the steel surface by using the hot dip method. Zinc coatings are insufficient to protect against corrosion, especially in chlorinated environments. Aluminum and its alloys stand out as an alternative material group to zinc in chlorinated environments. In this study, aluminum and aluminum alloy coatings, which are thought to be an alternative to zinc coating, were coated on the structural steel surface using the hot dip method. To examine how different aluminum alloys affect the corrosion and high- temperature oxidation properties of steels, nearly pure AA1050, high Cu content AA2024, and high Mg content AA5083 alloys were coated on structural steels. The coating process was carried out by dipping the structural steels into molten aluminum baths kept at a constant temperature of 700°C for 1, 3, and 5 minutes. The optimum adhesion and surface properties were obtained from dipping time for 3 minutes. The properties of coatings and intermetallic structures formed at the coating-steel interface were examined using an optical microscope, X-ray Diffractometer (XRD), Scanning Electron Microscope (SEM), and Energy Scattering Spectroscopy (EDS) systems. To examine the high-temperature oxidation properties of the coatings, the coated samples were oxidized for 24 hours at 750°C under open-air conditions, and the changes in weight were investigated. Immersion corrosion tests were performed in 3.5% NaCl solution, and corrosion losses and degradation patterns were investigated. As a result of the studies, it has been determined that the Al coatings produced by the hot dip process significantly increase the oxidation and corrosion resistance of the structural steels. 1.Introduction Since the surfaces of structural steels have a thermodynamically unstable structure, they generally want to return to their thermodynamically more stable oxide forms. This makes it inevitable for structural steel to corrode in many aggressive environments [1]. To eliminate the corrosion problems, it is necessary to use more durable materials instead of steel, protect the steel surface with corrosion protection systems, or improve the surface properties of steel. Surface modification techniques or corrosion protection systems are much more economical than using materials with high corrosion resistance, such as stainless steel. For this purpose, materials with better corrosion resistance can be deposited on the structural steel surface. Preferred materials are generally metals that are electrochemically more active than iron, such as zinc, aluminum. While these elements act as anodes, they protect the base material (Fe) cathodically [1]. Zinc coatings (galvanizing) are widely used on structural steel surfaces due to their low cost and superior sacrificial anode effect. Recently, there has been a need to find some alternatives to galvanized steels due to the limited mineral resources of zinc metal and fluctuations in its price [2]. Besides, the zinc coatings degrade rapidly, especially in chloride (Cl - ) containing environments, causing material loss and environmental pollution. Some negative properties of galvanizing led to the search for alternative coating materials. Aluminum is another coating material used in the surfaces of structural steel. Aluminum is one of the most widely used non-ferrous metals due to its low cost and unique properties. Pure aluminum has low tensile strength but can exhibit good mechanical properties with the addition of some alloying elements. Aluminum alloys play a critical role in the aviation, transportation, and building industries, especially as a result of their specific strength. Aluminum reacts naturally with the oxygen in the atmosphere and forms a thin protective oxide layer defined as Al2O3. This oxide layer stabilizes the surface and prevents further reaction of the metal with the environment [3]. Aluminum-coated steels have been widely used in vehicles, bridges, highway structures, pressure vessels, and many other places since their entry into the industry [4,5]. There are many methods for coating steel with aluminum. Some of these are arc/plasma spray coating, cladding, electrolytic coating, and hot dip coating. Hot dip aluminizing is applied to steels where heat and oxidation resistance are the primary requirements. At the same time, considering environmental protection, affordability, and suitability for mass production, and superior corrosion resistance, hot-dip aluminum coating is an efficient and convenient method [6-11]. Different intermetallic phases are formed between the steel and aluminum layers due to the aluminum coating process by hot dipping on the steel surface. These phases generally have a very hard, thick, and brittle structure. In this study, aluminum alloy coatings were applied by the hot-dip method on low carbon structural steels to improve corrosion resistance and high-temperature oxidation resistance. AA1050, AA2024, and AA5083 series aluminum alloys are used as coating materials. The coating process was carried out in a liquid aluminum bath fixed at 700°C and at different immersion times (1, 3, and 5