Steel Manufacturing Processes:

Electric Furnace:

It is a small open-hearth crucible mounted on trunnions. A typical furnace may have capacity of from 1 to 100 tons. From the top, carbon electrons are brought close to the scrap steel and pig iron charge and an arc is struck. The arc melts the metal and burns out the carbon. Since no air is brought into the system, the result is a steel with fewer air bubbles and interstitial oxygen or nitrogen atoms. Air or furnace gases do not touch the metal.

One of the reasons why the electric furnace is used to produce alloy steel is that the heat can be regulated more precisely than in other steel making furnaces. Electric furnace can be operated to conserve valuable alloying elements that would be burned up and lost in other kind of steel making furnaces.

Main drawback is the tremendous power requirements. Three phase 200 V electricity is used. The transformer and the power transmission lines must be capable of handling upto 30,000 KW. The electrodes in the furnace may range from 12- 29 inches in diameter and draw up to 25,000 A each.

The carbon in the electrodes is burned off and must be fed into the melt automatically. Each ton of steel requires about 15 lb of electrode and about 400 KW or about 200 W per pound of steel. Sometimes, electric arc furnace is used in conjunction with other converters to produce high quality steels.

This method is chiefly used to make pure steel or steels which require exact specifications and many alloy steels are produced in electric furnace. High Carbon steels, Special alloy steel and High Speed Steels are made this way. They are used for cutting tools, die and inserts.