What is steel? Knowledge and major type of steel
Iron is an element that plays the important role in daily life application and widely well known. Iron is classified into 2 types: iron and steel, which both of them have several different features but the most often called whole of them that the “iron”.
General characteristics of iron and steel
The scientific symbol of Iron is Fe which is often found in the nature. It has reddish brown color. When it was close to the magnet, it will sucks together. The most area of the iron discovery is underground of rock layers at the highlands and mountains. It is in the form of ore which has to smelt it out to obtain pure iron and can be applied.
Steel is an alloy that is mixing between iron, silicon, manganese, carbon and a few other elements to provide high flexibility property. It is also excellent durable, strength and resistant to impact force and natural conditions. And the steel is not discovered in natural not like the iron because of it is made by human application. At the present, steel is widely used due to there are low cost. Therefore, it is very cost effective and has remarkable feature as same as the iron.
How can classify the steel type?
For the type of steel, it can be classified into 2 groups are:
Cast iron is an iron formed by casting with amount of carbon about 1.7-2%. So, the iron has the hardness but there is the brittleness at the same time. Therefore, cast iron can only be formed by casting method. It cannot be formed by rolling or other methods. In addition, cast iron can be subdivided as follows.
- Gray cast iron is a cast iron with a carbon structure in the form of graphite due to there is plenty of carbon and silicon as the components.
- Steel cast iron is high strength iron, good resistance to abrasion but brittle, so it is easy to fracture. This type of cast iron will has lower amount of silicon than gray cast iron as well as there is carbon in the form of iron carbide, or so-called cementite.
- Spheroidal graphite cast iron is an iron with graphite structure. It contains magnesium or cerium in the molten metal that provide the shape of the graphite become spheroid. It also has a better mechanical properties and more remarkable features. Graphite cast iron is widely used and more applied in the industry.
- Malleable cast iron is an iron that passed heat treatment to provide carbon in a carbide structure decomposition and combine with spheroidal graphite and become ferrite or perlite. It has tenacity more than steel cast iron and it is the most popular for applications.
- Alloy cast iron is a type of iron that mixed with many elements together which will improve the properties of iron especially thermal and abrasion resistance. This iron is commonly used in the work with heat application.
Steel has tenacity more than cast iron and it can be formed by mechanical method. So, this type of iron is popular more widespread and widely used. The steel that often found in daily life includes steel plate, car frame steel, or steel bar, etc. In addition, carbon can be classified into the following subgroups.
Carbon steel contains carbon as the main component and a few other ingredients. It depends on what element is attached to in the smelting process. Therefore, carbon steel can be subdivided based on other mixed elements as follows.
- Low Carbon Steel contains carbon less than 0.2% and has very low strength. So, it is easy to roll as sheet such as steel bar and steel plate.
- Medium Carbon Steel contains carbon around 2-0.5% and has medium strength. It can be used as a piece of machinery.
- High Carbon Steel contains carbon more than 5% and has very high strength. It is commonly heat-treated to enhance the strength and good resistance to corrosion. So, it is used to make the tools that require hard surface.
Alloys Steel is the steel mixed with other alloys to provide the properties of steel to meet as required. This type of steel usually has the ability of corrosion resistant and electrical conductivity including the magnetic properties as well. It is divided into 2 categories are Low Alloy Steels and High Alloy steels. Low Alloy is a steel that mixed with other elements less than 10% and High Alloy Steel is a steel that mixed with other elements more than 10%.
Iron is the element that mostly used in daily life and is widely well known due to the features that are suitable for use in many areas but there are some disadvantages about its heavy weight that difficult to transport. However, steel is still popular and used in the industry or various machinery manufacturing and also used in house building because of it has very strength and durable.