Carbon steel


Carbon steel is composed of a mixture of two main elements metal (iron) and non-metal (carbon). However, it may contain some other alloying elements such as cobalt manganese, and nickel, marking the desired capacity.
Carbon steel
Carbon steel 
carbon steel can be classified as follows:

  • Low carbon steel
  • Medium Carbon Steel
  • High Carbon Steel

  • Carbon content

    As the carbon percentage increases, steel has the ability to become hard and strong through heat treatment; however, it becomes less ductile. Despite the heat treatment, a high carbon content reduces weldability. For example:

  • Carbon content in low carbon steel is 0.5 to 0.30%.
  • Carbon content in Medium carbon steel is 0.30 to0.50%
  • Carbon content in High carbon is 0.50 to1.50%

  • Low Carbon Steel

    Low carbon steel can be mechanized easily. It is also divided into grades according to different amounts of carbon such as

  • With 0.05 to0.15% carbon content, rivets, screws, presses, sheets, pipes, nails, and chains can be manufactured.
  • With 0.15 to0.30% carbon content, Plates, structural shapes, and bars can be manufactured. With a melting point (1539 to 1515) degrees centigrade, low-carbon steel can be machined easily. It is also relatively inexpensive.
  • Weldability

    At present, low carbon steel is the most commonly used material just because of its strength and comparatively inexpensive. Low carbon steel can be welded by almost all welding processes such as:

  • Oxy-acetylene welding
  • Flux shielded metal arc welding
  • Gas metal arc welding
  • Submerged arc welding
  • Plasma arc welding
  • Thermit welding
  • Resistance welding
  • Electroslag welding
  • Brazing 

  • Medium Carbon Steel

    Welding of medium carbon steel is comparatively difficult due to the high carbon content that can cause weld brittleness. The melting point of High carbon steel is 1515℃ to1492℃, and it is harder than low carbon steel.
    Medium carbon steel has a carbon content of 0.30% to 0.50%. During welding, the weld hardens into the joint and forms martensite in the heat-affected zone due to rapid cooling which may cause cracking. This can be avoided by using special welding techniques and appropriate electrodes.
    Medium carbon steel can be welded by the following processes:

    High Carbon Steel

    High carbon steel has a welding range due to its high carbon content, the melting point of high carbon steel is 1492–1405.
    Originally high carbon steel is welded for repair purposes using the following welding processes:
    • Resistance Welding
    • Thermit Welding
    • Shielded Metal Arc Welding
    • Oxyacetylene welding

    ASTM code for Carbon Steel


    ASTM A53 Gr. A/B, ASTM A106 Gr. A/B/C, ASTM A333 Gr.1/Gr.6,

      ASTM A178/179/192, ASTM A334 Gr.1/6.

    Wrought Iron fittings :-

    ASTM A234Gr.WPA/B, ASTM A420 Gr.WPL6

    Forged Fittings:-ASTM A181. ASTM A105, ASTM A350 LF1/2.

    Cast Fittings:-ASTM A216, ASTM A352 LCB/C.

    Plates: -ASTM A285, ASTM A515, ASTM A516.

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