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Facts about Stainless Steel - Properties and Uses
Stainless steel is an iron based alloy. It is a strong alloy and is resistant to corrosion and rusting. It can withstand high temperatures.
It is also known as "inox" steel or corrosion resistant steel. It has a minimum of 10.5 % of chromium and more than 50% of iron.
Stainless steel may also have an addition of Nickel, Molybdenum, and Titanium to improve the structure of stainless steel.
Stainless steel is produced in the form of coils, sheets, plates, bars, wires and tubing to be used for different purposes.
Stainless steel was discovered by Harry Brearley when he was researching for an alloy that was resistant to corrosion and could withstand high temperatures.
Why is stainless steel resistant to corrosion?
The chromium present in steel forms a protective layer of chromium oxide. This protective layer helps to prevent further corrosion of the metal surface and makes it resistant to staining.
Even if the surface layer of chromium oxide is scratched off the chromium content in the stainless steel will again form another protective layer of chromium oxide when it comes in contact with atmospheric oxygen. This makes stainless steel resistant to corrosion for a very long time. It has a life expectancy of 100 years.
Composition of stainless steel –
Stainless steel is an alloy. The term “alloy” means a mixture of metals.
The following elements are added to improve the quality and structure of steel –
1. Chromium – makes the alloy resistant to corrosion.
2. Carbon – carbon is often added to increase the hardness and strength of the alloy.
3. Nickel – Nickel may or may not be added. The addition of Nickel helps to withstand high temperatures and also aids in making the alloy corrosive resistant.
When the need arises, Molybdenum and Titanium are added to make the stainless steel more resistant to corrosion and high temperatures.
The three major classes of Stainless Steel
1. Austentic Stainless Steel
Austentic stainless steel is composed of 16-26% Chromium, 6-22% Nickel, has a low carbon content and is non-magnetic. The addition of Nickel increases corrosion resistance.
This type of steel is very sturdy and is hardened even more by the process of heating, cooling and heating again. It is commonly used for making knives and cooking utensils. It is highly resistant to scaling and high temperatures.
2. Ferritic Stainless Steel
Ferretic Stainless Steel is a chromium-iron alloy with 17-27% chromium and low carbon content with magnetic properties. Ferritic stainless steel is used in the production of cookware and household appliances.
3. Martensitic Stainless Steel
Martensitic Stainless Steel is an alloy of chromium and iron with 10.5%-17% chromium along with carbon. It is strong and hard but brittle and difficult to mould or weld. It is used for making equipment for chemical and oil industries. It is also used to make surgical instruments.
Stainless Steel - The ideal metal alloy for cookware
- Stainless steel is ideal for kitchen utensils because it has no pores or cracks for germs to enter and breed.
- It is very easy to clean and needs minimum care. It does not chip or rust easily.
- It does not react with acidic foods and does not change the flavor of the food in any way.
- Stainless steel is totally recyclable.
The many uses of Stainless Steel
1. Stainless steel is used to make many types of cookware, cutlery, and utensils.
2. It is utilized in the field of medicine to make medical equipment and surgical instruments.
3. Stainless steel is used to make electrical supplies, plumbing supplies, screws, nuts, washers, keys, latches, handles, wires, chains, belts, tools, machine parts, etc. for industrial purposes.
3. It is used in the automobile industry for the production of two wheelers and four wheelers.
4. Stainless steel is used to make jewellery and watches because it is pliable and can be molded into many shapes easily. It does not cause any skin allergies. The 316L grade of stainless steel is used for making jewelry.
5. It is used in the construction of buildings both in the infrastructure and for decorative purposes on the exterior of the buildings. The Type 316 grade of stainless steel is used on the exterior of the Petronas Twin Towers and the Jin Mao Building.
6. Stainless steel is also used in bridges, monuments, and sculptures. It is also used in the manufacture of cars, railcars and aircraft.
7. Stainless steel is also used in the production of firearms, handguns, and pistols.
Role of stainless steel in improving the environment
Stainless steel is 100% recyclable. Stainless steel does not have any negative impact on the environment. Any stainless steel object has 60 % recycled stainless steel.
Most of the stainless steel that is used for many purposes is made up of
- 25% old scrap
- 35%new scrap
- 40% new raw materials
Stainless steel plays a significant role in saving the environment and life on earth.
1. Stainless steel helps to deliver clean drinking water
Drinking water supply pipes are made of stainless steel because it does not contaminate water because of it’s high resistance to corrosion and rust.
2. Stainless steel helps to bring down pollution
Diesel filters remove 95 % of smoke and 85 % of soot particles from the exhaust gas of a diesel engine. These diesel filters are made of stainless steel because it can easily withstand high temperatures.
3. Stainless steel is recently being used in many applications that help to reduce the consumption of fossil fuel.
It is used in
- Condensing boilers
- Rooftop solar panels
- Fuel cells
5. Waste water plants use stainless steel pipes to transport waste water products because it does not corrode easily and is low maintenance.
6. Stainless steel is used in the construction of plants that
- Dispose waste
- Recycle paper and cardboard
7. Stainless steel is used to make recycling bins that are placed to collect waste materials for recycling.
Stainless steel improves the quality of life and helps to save the earth in countless ways.