WEATHER VERSUS STEEL

Steel is not a non-corrosive material which you can leave exposed. 

Usually STEEL is not  selected  for it's corrosion  resistance but for properties such as strength, ease of fabrication and cost .

We are using  steel on a daily basis (kitchen utensils) and in other cases we are using this also as a building material (RCC) .The corrosion will happen depending on how we treat the steel. Salt acts as a corrosion agent for steel . Salty condition can have a similar affect on the building also .The rate of corrosion varies in different areas.
 Factors that determine the rate of corrosion include - 
wind speed and direction
coastal topography
wave height etc. 
We can see higher corrosion rates in more polluted industrial areas.

All steels rust in moist atmospheres. If we add the chemical components on steel it might reduce the rust on steel. Some elements that resist atmospheric corrosion are nickel, chromium etc.The life of paint  that is applied to resist corrosion can be  lengthened by decreasing the corrosion under the paint layer . Rusting will happen usually in the first year of atmospheric exposure and will increase based on the moisture content in the air.


WEATHERING STEEL ( HSLA- high strength steel alloy)
There is no need for initial painting or galvanizing.
It corrodes at first to form a tight oxide layer and so prevents further corrosion.
It is different from other steels as they form porous oxide layers that allow corrosion .

-J Prasanna

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