The destruction of a substance (usually a metal) or its properties because of a reaction with its environment is known as corrosion. And one of the most commonly affected is steel. Steel is the important building block of all forms of industrial and commercial construction applications, and its corrosion can mean serious trouble.

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In many structural engineering investigations, the prime reason for the collapse was the result of corroded steel structures. There are many causes of corrosion and most of them can be easily prevented.

The Common Types of Corrosion in Steel

Basic Corrosion

The basic corrosion or rust, as we call it, is the most common corrosion problem. The start of this form of corrosion is simple. All that is needed is oxygen and some moisture. And these two elements are present in abundance. The corrosion process is simple here –

  • The iron (Fe) atoms in steel lose some electrons and become positively charged. These ions attract negatively charged ions.
  • Water (H2O) and oxygen (O), mix together and become negatively charged, which attract themselves to the positively-charged iron atoms. The resultant chemical is called iron hydroxide (4Fe(OH)2).
  • This newly produced Iron hydroxide continues to react with oxygen, yielding 2Fe2O3.H2O – commonly known as hydrated iron oxide OR brown rust.

Unless an external layer is present on bare steel, the surface will be breeding ground for more rust. The reaction will continue to occur. That’s why rust proof coatings are so important in steel applications.

Bimetallic Corrosion

This is a complex form of corrosion and occurs because of contact between of steel with some other form of metal. The reaction occurs between the alloys in the two metal structures. This is commonly found in steel that is buried in the ground or submerged in liquid.

Environmental Corrosion

This is not actually a form of corrosion on its own but it’s a catalyst that accelerates the corrosion in steel. The toxins and other elements in the environment help in the reaction of the corrosion. This type of corrosion is common in industries and areas where toxic emissions and gases are present.

Common Causes of Corrosion in Steel-

Uncoated steel

Inadequate treatment considering the environment

Lack of maintenance

Lack of ingress and moisture resistance

Leaky roofs, plumbing leaks, standing water, etc.

Incorrect design or installation of steel structures

Simple Steps to Prevent Steel Corrosion

Use Stainless Steel if the wherever possible – Building a stainless steel structure is not feasible in all cases but wherever applicable, implement it.

Protective Coatings- Protective coating is the most common and cost-effective way to prevent corrosion. Steel coatings act as a barrier to prevent that prevents the transfer of electrochemical charge from the corrosive solution to the metal underneath.

Control the environment- As mentioned earlier, some form of toxins and other chemicals present in the environment can increase the rate of corrosion. So by taking measures to prevent such exposure to sulfur, chlorine, or oxygen in the surrounding environment, can increase the life of the steel components.