Steel: Difference between Steel and Wrought Iron, Carbon content in steel

            The steel forms an intermediate stage between cast-iron and wrought-iron. The cast iron contains carbon from 2 to 4 per cent. In wrought-iron, The carbon content does not exceed 0.15%. In steel, the carbon content varies from anything below 0.25% to 1.50% maximum. This is due to the fact that carbon, if in excess of 1.5%, does not combine with iron and it is present as free graphite. Thus the dividing line of cast iron and steel is the presence of free graphite. If there is no free graphite in the composition of a material, it is said to be steel. On the other hand, the presence of free graphite indicates that the material is the cast iron.

Steel Pipe

            The steel become harder and tougher as its carbon content goes on increasing and at the maximum level of 1.5%, all the carbon gets into chemical combination with iron and none of it exists in its free state. The cast-iron can take up only compressive stresses  and its use is limited to the compression members only. The wrought-iron of a fibrous nature and it is suitable to resist tensile stresses.

  • How to distinguished between steel and wrought iron:-

            The steel is suitable for all constructional purpose in general and hence it has practically replaced cast iron and wrought iron in the present day practice of building construction. It is equally strong in compression as well as in tension. If a drop of nitric acid is placed on steel, it will produce a dark gray stain due to presence of higher percentage of carbon content. If the same procedure is carried out on wrought iron, the stain will not be appreciable. Thus the mild steel and wrought iron can be easily distinguished by the simple process

  • Use of steel:-
          On the basis of carbon content, the steel is designated as the mild steel, medium carbon steel or high carbon steel.

Note:- The carbon content of mild steel is about 0.10 to 0.25 %. When carbon content is less than 0.10 % , it is known as the dead steel or very low carbon steel. The carbon content of medium carbon steel is about 0.25% to 0.60%. The high carbon steel is also known as hard steel and its carbon content varies from 0.60 to 1.10%.

Steel Bowls

  • Mild steel contain carbon content upto 0.10% is used for Motor body, sheet metal, tin plate,etc
  • Medium carbon steel carbon content upto 0.25% is used for boiler plates, structural steel, etc.
  • Medium carbon steel carbon content upto 0.45% is used for rails, tyres, etc
  • Medium carbon steel carbon content upto 0.60% is used for Hammers, Large stamping and pressing dies, etc.
  • High carbon steel carbon content upto 0.75% is used for sledge hammer, springs, stamping dies, etc.
  • High carbon steel carbon content upto 0.90% is used for Miner's drills, smith's tools, stone mason's tools, etc.
  • High carbon steel carbon content upto 1.00% is used for chisels, Hammers, saws, wood working tools, etc.
  • High carbon steel carbon content upto 1.10% is used for Axes, cutlery, drills, knives, punches, etc.
                  Steel is most widely used for the development of industry, automobile, tool etc. Steel is need for the existence of the heavy and light engineering industries, for ship building, railways and rolling stock, automobiles, sheet metal industries, power generation and electrical industries, dailu house hold appliances, etc. 

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