Is the hardness of steel or pig iron hardness?
Pure iron containing more than 0.02% of carbon will become hard to change, lower able to pull wire, rolling thin white iron, such as the use of low carbon steel. The steel in the range of 0.25% to 0.6% of carbon is called medium carbon steel. Its hardness is moderate, and it can be rolled into building steel, steel plate, iron nails and other products.
Iron is a soft metal, is not prepared, nor cast iron pot, plough. But when pure iron contains a certain amount of carbon, it becomes the steel we use in all respects.
The carbon content of 0.6% to 2% when the iron becomes high carbon steel with high hardness, can be prepared, is the norm. Low, medium, high carbon steel together called "carbon steel"". If the iron content of carbon more than 2%, it becomes hard and crisp, can be cast iron pot, radiator, plow and other pig iron. Generally, the carbon content of pig iron is 3.5%-5.5%. Therefore, the difference between pure iron, steel and pig iron is mainly due to the difference in carbon content in iron.
