The effect of Centrifuged Hot-Dip Galvanisation (SHDG) Process on the Corrosion on Nuts

Authors : Hüsnü Gerengi, Muhammed Maraşlı, Mesut Yıldız, Kader Coskun, Yusuf Güner, Beyza Aşıkoğlu

Pages : 13-25

Doi:10.29130/dubited.1460076

View : 46 | Download : 35

Publication Date : 2025-01-30

Article Type : Research Paper

Abstract :The bolted fasteners, widely used in various industries, are the fundamental structural components most commonly used in the assembly of steel structures. Bolted fasteners offer advantages such as versatility, reliability, minimal maintenance and inspection costs, easy and fast assembly, and good strength under variable loads. However, fastener failures occur due to complex loading conditions, hydrogen embrittlement during fabrication or service, fatigue failures due to alternative stress, and combined effects of corrosion and stress. Therefore, the study of fastener failure is critical for safety in both every day and industrial applications. Zinc plating has long been a preferred method of protecting fasteners from corrosive environments. One of the most commonly used methods for coating fasteners today is the centrifugal hot dip galvanising (SHDG) process. SHDG is suitable for outdoor applications on small metal parts (bolts, nuts, washers) that cannot be hot dip galvanised. Centrifugation removes all excess zinc from the threads of bolts. Oversized nuts fit perfectly on very small parts. In this study, nut samples coated with SHDG were exposed to corrosion in a corrosive environment according to ASTM B117 standards. At the end of thirteen (13) days, the outer surface of the nut attached to the screw was cut and the screw steps were examined using scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The results show that the zinc coating on the surface produced by the SHDG process is effective in protecting the metal nuts against corrosion. The zinc patina begins its development with exposure to oxygen in the atmosphere, forming a layer of zinc oxide on the surface. Moisture from rain or humid air reacts with the zinc oxide to form zinc hydroxide which then reacts with carbon dioxide present in the air to form the tightly adherent, insoluble zinc patina.
Keywords : Korozyon, Somun, Santrifüj Sıcak Daldırma Galvaniz