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Understanding Corrosion Problems in Fasteners

March 11, 2020

Fasteners take a huge role in maintaining the strength and integrity of a structure or object. However, there are some aspects of fasteners that you cannot fully control and avoid. Corrosion, which is a process of gradual destruction of metallic materials, can drastically affect the quality of your fasteners. In fact, it is considered one of the main roots of damage among these hardware devices.

Concept behind Corrosion

Each type of metal has its own electric potential. When two metals interact with water, a galvanic cell is created. At the same time, an electric current will flow between these two metals. This galvanic flow will then contribute to the degrading of one of the metals. However, the metal with a higher electric potential will degrade faster than the one with lower electric potential.

Some examples of metal with high electric potential include zinc, galvanized steel, and magnesium. Silver, gold, zircononium, platinum, and titanium, on the other hand, are metals with low electric potential. 

One specific factor that makes two metals corrode faster is when these metals are far away from each other on the electric potential spectrum. So, if a fastener that is made from high-potential metal is installed in a low-potential metal, then expect these metals to corrode faster. 

Types of Corrosion

The appearance of corrosion can be spontaneous. Meaning, it can occur anywhere. Corrosion may even look different, depending on some factors and variables. To better understand corrosion, here are some of its types that may appear on your fastened structures or objects.

  • Galvanic Corrosion: This type of corrosion occurs whenever two different types of metals are joined and immersed in a conductive solution. As the electricity flows from one metal to the other, the corrosion process will then appear.
  • Uniform Corrosion:Uniform corrosion occurs whenever a fastener is not properly coated or plated with anti-corrosive coating. The degrading effect of corrosion is visible to the entire surface of a fastener.
  • Crevice Corrosion:Unlike uniform corrosion, this type of corrosion only appears in small gaps and openings in a fastener that are not well-ventilated. 
  • Pitting Corrosion:Pitting corrosion is somewhat close to crevice corrosion. However, with this type of corrosion, the holes in a fastener are so small that they are very difficult to see. Pitting corrosion is common to fasteners made from nickel and chromium.
  • Intergranular Corrosion:Intergranular corrosion happens whenever a stainless steel metal is being welded or hot-formed. To prevent this from happening, welders quickly plunge these metallic parts into the water to cool them down.

Preventing Corrosion

Fortunately, some measures can be done to prevent the appearance of corrosion. For one, you must use insulation or coatings to seal fasteners that use different metal from the material that they will be installed into. Your fastener must also bear constant pressure from its load to avoid corrosion. Lastly, you must always look out for the materials that you use. You must assess their properties so that you can find a solution before the corrosion happens. If possible, choose fasteners with a similar electric potential to the materials they are fastening together.

Fasteners help join two objects together. However, you must be mindful of the damaging effects of corrosion. We at eBolts Online Store are willing to help you supply your needed answers when it comes to your fastener needs and solutions.

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TCI Fasteners - Topcope
13 Slater Parade, Keilor East VIC 3033 Australia

Telephone: (03) 9336 0155

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