The steel type that has extreme resistance for corrosion is called as stainless steel. The highly corrosion resistant nature of the stainless steel is due to an oxide film that is rich in chromium and is located on the surface. This layer is called as passive layer and also has different amounts of manganese, carbon and silicon. The elements like molybdenum and nickel are also responsible for its increased formability as well as enhanced resistance for corrosion.
There are generally five types of the
stainless steel. These are inclusive Ferritic, Austenitic, Martensitic, Duplex and Precipitation Hardening. Ferritic stainless steel is the simplest composition that comprise of iron & chromium. The name of this steel is kept after the crystal structure carried by ferrite. This type of stainless steel is magnetic in nature and is utilized in products like automobile trim, dishwashers, etc. It is the cheapest type of stainless steel welding and used in home heating systems and mufflers.
Another type of stainless steel is austenitic stainless steel. It is developed by the addition of elements like nickel, nitrogen and manganese. This type of stainless steel is made for welding and also for forming process. This type of stainless steel is used in cookware as well as in baskets of
washing machine.
The martensitic stainless steel is quite familiar to the ferritic type as both of them contain chromium. However, martensitic steel carries higher levels of carbon equivalent to one percent. This carbon is responsible for making the hardening and tempering steel. This type of stainless steel is usually used in long products. This kind of steel has low welding ability and low formability. This is used in cutlery & in valve parts.
Another kind that is the duplex steel is a mixture of 50 % ferritic stainless steel and 50 % austenitic stainless steel. This kind of steel is stronger and is highly resistant towards cracking from stress corrosion. This steel that has welding abilities and magnetic nature finds its usability in pipes, architectural structures and so on.
The precipitation hardening stainless steel is strong due to the addition of copper, aluminium, and niobium. Due to heat treatment at high temperatures, the steels become strong due to extremely fine particles. Precipitation hardening stainless steels can be machined into complex shapes and sizes. The property of corrosion resistance in this type of steel is comparable with the standard austenitic steels and is better than ferritics.
The list of uses of the incredible stainless steel is endless. It has been a part of innumerable things. From huge architectural structures like gateway arch and former portion of Chrysler Building to small products like chairs, utensils, stainless steel wire rods, stainless steel flats and so forth, stainless steel is used in almost everything.
