What is Stainless Steel?
Stainless steel is able to resist corrosion because of the additional alloying elements in its chemical makeup. While plain carbon steel consists of mostly iron carbon, stainless steel has substantial additions of chromium to help it resist corrosion. The chromium, sometimes other alloying elements, are added to the stainless steel during the initial melting process, prior to it being formed into any particular shape.
What is Galvanized Steel?
Galvanized steel is a type of steel that has been coated in a layer of zinc that helps prevent the underlying steel rusting. This layer is usually quite thin, often measured in thousandths of inches microns. To create galvanized steel, the zinc layer is typically added well after melting, refining, shaping of the steel plate sheet. Sometimes it is even done after manufacturing processes have been performed on it such as bending welding.
How Does Stainless Steel Resist Corrosion?
Stainless steel resists corrosion because of the added chromium ( sometimes other additional elements). Corrosion occurs on carbon steel when the iron the steel is allowed to combine with oxygen in its surrounding environment. The chromium in stainless steel is able to prevent this as it combines with the oxygen forms a passive layer of chromium oxide. This layer of chromium oxide prevents the formation of iron oxide, (also known as rust), in many situations, so long as the chromium content of the steel is great enough. Different grades of stainless steel designate dictate the required amounts of chromium other alloying elements, which helps to indicate the level of corrosion resistance.
How Does Galvanized Steel Resist Corrosion?
Galvanized steel resists corrosion because of the zinc coating covering the carbon steel. The zinc layer serves two purposes:
It prevents oxygen coming into contact with the steel, therefore reducing the possibility of corrosion.
Even if the zinc coating were to experience minor damage expose small amounts of iron to the atmosphere, the nearby zinc on the rest of the coating is more reactive than steel. This makes the zinc more likely to attract an oxygen molecule than the iron, which prevents rust forming on the steel.
The Difference Between Stainless Steel Galvanized Steel
Stainless steel usually has better corrosion-resistant properties than galvanized steel. If the stainless steel becomes scratched, it can still maintain corrosion resistance around the affected area. However, if the zinc layer of galvanized steel is damaged, it can leave the underlying carbon steel exposed vulnerable. because galvanized steel is often dipped in zinc in large sheets then cut to size, the edges the cuts are made are left exposed making it possible for rust to occur.
Stainless steel is also generally considered to be more aesthetically pleasing than galvanized steel, as stainless typically has a shiny, silver-like color, versus the dull-grey pattern of galvanized steel. However, stainless steel is also often more expensive than galvanized steel.
Applications of Stainless Steel
Stainless steel is typically used in applications the risk of corrosion is a major concern permissible. Areas of use for stainless steel include:
Food processing equipment
Pharmaceutical manufacturing equipment
Aerospace engine components
Certain types of fasteners
Applications of Galvanized Steel
Galvanized steel is used for applications corrosion is desirable, but small amounts may be permissible aesthetics are much of a concern. Applications for galvanized steel include:
Some types of fasteners