Steel provides life to the designs of humanity. It has remained an invincible metal through the centuries, but how is it refined, and recycled? What is the difference between cast iron and stainless, and what are the primary alloys of steel?
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"As strong as steel" is the common comparative that you hear every day. Steel is a major commodity used in our day-to-day life, from the metal spoons on our table to the cars we drive. The applications of steel are enormous. It is available in various alloyed forms to take care of various needs. Some of the important applications of steel include:
In mild steel form, it finds use in constructional activities like bridge building.
In alloyed steel form, it find applications for the manufacturing of gears and shafts, and is also used for machining steel itself when it is alloyed with chromium and other elements to form high speed steel.
Steel is basically processed out from iron ore mined from deep inside the earth. Iron ore is the mother of all forms of iron available in the world. The iron ore is smelted out to form pig iron, the raw and purest form of iron. The pig iron is usually distributed in the form of ingots. Pig iron is then combined with other elements such as carbon, chromium, etc. to obtain materials like cast iron, steel, and alloy steel.
Steel plants do the job of separating the pig iron from the iron ore. Steel is obtained by various processes like crucible, Bessemer's, open hearth, and electrical processes. Further down the line industries like foundries or forging units provide shapes and improve the mechanical properties of the material by addition of elements to the basic form of iron - pig iron.
Iron is the basis for many different forms of products. Iron is categorized into cast iron and alloy steel, which can provide confusion to many engineers, too. Cast, or grey, iron is one form of iron which is cast in a mold by the re-melting of pig iron, except that that it has a higher percentage of carbon in it. Cast iron tends to have a better compression strength and good vibration damping facilities compared to counterpart steels. Alloy steel is basically iron mixed with various elements in order to provide enhanced mechanical properties and heat treatment capabilities.
Steel can be produced either by casting or by forging. The difference between casting and forging is that here again the mechanical parameters vary between the cast and forged steel. Cast steel has the advantage of being produced in intricate shapes due to the casting process. Further they are very good chances for the occurrence of fault inside casted steel like blowholes, warps, shrinks, etc. which acts as a disadvantage for cast steel. Forged steel on the other hand is very good in mechanical parameters and is devoid of internal faults. Forged steel cannot be manufactured in intricate shapes, but it can be made in regular shapes such as rounds or flats. Smithing is another type of production of steel components which are quite small. Smithing is mainly used in the manufacture of small tools, horse shoes, and antique weapons like swords.
The mechanical properties of steel can be controlled by means of heat treating it or annealing it. A heat-treated steel component is relatively stronger and tougher, and possesses better wear resistance. Some types of heat treatment like annealing are required in order to make the component machinable or workable.
Plenty of articles manufactured from steel are scrapped every day. (Russia has vast reserves left over from the Cold War. In 2007, they processed 37 million tons.) Right from small stapler pins to huge ships, everything needs to be scrapped after its intended life. Steel forms a major portion of almost all the scraped items. The scrapped steel can be put into use again; there is a possibility of recycling the steel and using it again. Huge chunks of steel are broken into smaller pieces, melted again and formed into ingots. These ingots can be utilized further for various other applications. The recycling of the steel not only saves the mining of the metal, but it also saves the environment.