Alloy steel

Alloy welding

Alloy steel

Metal alloying is the method that provided the specific type of steel 
Many times, normal steel can not be suitable for some specific job and need some special metal for that purpose. Metal alloying is the method that provided the specific type of steel for that purpose.  Alloy steel made up containing various types of elements such as nickel, chromium, nickel, vanadium, molybdenum, tungsten, cobalt, boron, copper, manganese, silicon, phosphorus, and sulfur, etc. The purpose of alloying these elements in steel to give more:

  • Corrosion resistance
  • Strength of ferrite
  • Hardenability
  • Grain size control
  • Temperature stability
  • Ductility 
Composition of Alloy steel
Element Percentage
C 0.2-0.4%
Si 0.3-0.6%
Cr 0.4-0.6%
Mn 0.5-1.0%
Ni 0.4-0.7%
Mo 0.15-0.3%
Fe Balance

Properties of ingredients




  • The Carbon element is responsible for hardness, tensile strength and mechanical strength in steel. Since carbon controls the hardness of steel, its melting point is also effective.



  • The Manganese element is responsible for markedly to strength and hardness and it lowers both ductility and weldability if present in high percentage with high carbon content in the steel.
  • The Silicon element is responsible for improved oxidation resistance and strengthens low alloy steel.
  • The Nickel element is responsible for the increased stiffness and resistance to impact.
  • The Chromium element prevented the corrosion and oxidation, also improves resistance to abrasion.
  • The Molybdenum element is responsible for the hardness of steel, it makes it granular, tends to be tough in nature, increases tensile and creep strength at high temperatures.
  • The Vanadium element is responsible for promoting fine grains in steel and increasing strength also.




  • The Tungsten element is responsible for the hardness of steel.
  • The Copper elements resist atmospheric corrosion.
  • Boran is responsible for hardenability.
  • Titanium reduces the martensitic hardness.

  • Types of Alloy Steel

    Alloy steel may be classified as follows:

  • Low alloy steel
  • Medium alloy steel
  • High alloy steel.
  • LOW ALLOY STEEL-Low alloy steels are good resistance to atmospheric and other mildly corrosive environments such as steel having yield strength values between 50000 and 80000 psi, low alloy steels are more expensive than carbon steel. The composition of low alloy steel is as follows:C-0.12%,Mn-0.60,Si-0.30%,Cu-1.1%,Ni-0.55%,Fe-Balance.

    Electrodes For Alloy steel

    The Detail of electrodes with material description.

    Welding Applications

    :- Alloy steel can be welded by mostly all welding processes, some common welding process for alloy steels are as follows:

  • Oxy-acetylene welding
  • Shielded Metal Arc Welding
  • Submerged Arc Welding.
  • Resistance Welding.
  • Thermit Welding
  • Gas Metal Arc Welding.
  • Automatic Hydrogen Welding.
  • Seam Welding
  • Brazing.

  • ASTM CODES FOR ALLOY STEEL


  • Pipes:-ASTM A335 Gr.P1/P2/P5/P7/P9/P11/P12/P22.
  • Tubes:-ASTM A234 WP1/WP5/WP7/WP9/WP11/WP12/WP22.
  • Forged Fittings:-ASTM A182F1/F2/F5/F7/F9/F11/F12/F22.
  • Cast Fittings:ASTM A217 WC1/WC6/WC9/C5/C12.
  • Plates:ASTM A387 Gr.2/Gr.5/Gr.7/Gr.9/Gr.11/Gr.12/Gr.22.
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