Protecting Steel with Galvanising

Steel has become synonymous with the concept of an unbreakable, incredibly strong material. After all, it’s no accident that the invincible Superman has been nicknamed the Man of Steel. However, steel is also susceptible to wear and tear from the elements – steel’s own Kryptonite – if left untreated and can corrode to the point of structural failure.

Protecting steel is critical in applications such as buildings made near the coast or other areas where water is an ever-present part of the environment. Sea air is particularly threatening to exposed steel as the salt acts as another contaminant.

Thankfully, engineers have developed many proven ways to protect steel from this catastrophic damage by affixing a coating that will keep it strong for years, decades or even longer. The most common method of protection is by painting the steel surface with specially-designed protective solutions. These have increased in durability and quality considerably over recent years, but there’s a way to make steel even tougher: galvanising.

What is galvanising?

The process started in a basic format over 150 years ago and evolved over time as new technologies and processes opened the way up for more improvements. The basic version is that the steel is “hot dipped” into a vat of molten zinc. Instead of merely coating the steel, the zinc actually forms a chemical bond with the steel surface, becoming one with it and forming an outer layer that water cannot penetrate.

The fusion of zinc and steel is where galvanism occurs. By adding a third element – electrolytes – electrons in the two metals will transfer causing a current of electricity to form a galvanic cell. The weaker metal (the “anode”) gives up electrons to the stronger one (the “cathode”), which in turn becomes stronger still. Over the years many experiments in which combinations of metals in the galvanisation process form the strongest bonds, and which ones weaken and strengthen in the process. In our example, zinc sacrifices its strength to service the steel.

Thanks to what are called galvanic cells, zinc continues to play a sacrificial role long after the initial galvanisation process occurs. If a galvanised steel panel is scratched to the point where both the paint and zinc layers are exposed, a galvanic cell is created by the zinc further deteriorating in order to protect the steel from water. This doesn’t necessarily mean that you can rely on these galvanic cells to provide indefinite protection, as damaged areas should be promptly repaired before further damage occurs.

New developments in galvanising

Experimentation with different materials in recent years has resulted in new alloy coatings being developed. One such combination, Galvalume, sports a combination of 55% aluminium, 43.4% zinc and 1.6% silicon. Aluminium oxides have proven to be stronger than zinc-based ones and having both in place offers a second layer of protection. As zinc is the anode in this setup, it diminishes upon contact with an abrasive material but still leaves the strong aluminium in place.

At ShapeCUT we bend, cut and shape steel in a practically unlimited number of ways, and always ensure that the steel plates we use is treated to handle all the wear and tear that will come to it in the years to come. Contact ShapeCUT today to find out what we can offer your business.