Why does salt water cause so many problems for metals?

Many people know that salt water is bad for metals and can cause rapid corrosion. But, why does this happen? What makes it so much more aggressive than fresh water? We want to take a closer look at this below. As a leading supplier of aluminium bar and plate, including marine grade 5083, it has been our pleasure to help clients choose the right metals for all kinds of settings. This includes marine locations.

Salt water is very harmful

Any environment that has a combination of moisture, oxygen and salt can be very hazardous for metals. These three factors can cause rapid corrosion, weakening a metal to the point it becomes very brittle and falls apart. As you would expect, there is naturally a much higher risk of this in coastal locations because of the salty sea water. There is also the extra problem here that bacteria in the seas and oceans will consume iron, and the excretions will become rust.

Two forms of corrosion

Interestingly there are actually two different types of corrosion occurring when salt water and metals meet. The first is electrochemical. This happens because the metal ions dissolve in water. At the same time salt water contains different ions and conducts electricity. The end result is electrons from different compounds attract to the metal ions, causing corrosion.

The second type is anaerobic corrosion. This happens when you expose a metal to salt water for a period of time. What happens here is the water will leave deposits of sulfates, including hydrogen sulfide. This itself causes corrosion. However, the hydrogen also attracts bacteria, which accelerates how quickly the metals corrode.

What you need to keep in mind is that exposure to salt water can cause many metals to corrode at five times the rate of fresh water. This can then double in higher humidity.

Why choose grade 5083 aluminium bar and plate?

There are several things you can do to reduce the risk of corrosion in salt water environments. For example you can minimise the amount of time items encounter the water. Plus you can rinse them off and use things like oil to protect boat hulls and engines. However, this can all be quite time consuming. Sometimes it is a better option to choose a metal that naturally has a high resistance to corrosion, even in these environments.

Grade 5083 aluminium is a great choice here. It has excellent corrosion resistance, particularly to salt water. This puts it far ahead of most other materials. At the same time, it is one of the strongest alloys and does not weaken after welding.

Speak to us to order metals

We are proud to be a company with a reputation for offering consistent high quality services and a wide range of products. Clients from various industries can come to us for help choosing and ordering metals. We can give them advice about the properties, forms, and more.

So, if you need aluminium bar and plate, particularly in grade 5083, we can help. Plus, we have other grades and lots of other materials too.

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