Things to know about AISI 4130 Seamless Pipe

Things to know about AISI 4130 Seamless Pipe

AISI 4130 seamless pipes

The American Iron & Steel Institute (AISI) has designated a number of steel grades for various applications, which are denoted by three to five-digit identifiers. To classify alloy steels, AISI four-digit numbers are used. 4130 steel is a common alloy steel that is used in a wide range of works; this blog will explore its properties briefly by explaining its composition, characteristics, and applications.

Pipes without seams or weld are known as seamless. In AISI 4130 seamless pipes Chromium and molybdenum are alloying elements which give it excellent strength-to-weight ratio and they are much harder and stronger than standard 1020 steel pipe, but they are difficult to weld. They require pre and post-weld thermal treatment to avoid cold cracking. 4130 pipe works best in high-pressure and high-temperature applications. These are used in complex assemblies due to their design.


The chemistry of AISI 4130 seamless pipes is as follows;

Carbon  0.28% – 0.33%
Manganese  0.40% – 0.60%
Phosphorous  0.04% max
Sulfur  0.04% max
Silicon  0.15% – 0.35%
Chromium  0.80% – 1.10%
Molybdenum  0.15% – 0.25%



Few properties of this grade are:

  • Density (Metric) –  7.85 g/cm
  • Hardness – 217 (Brinell scale) – 95 (Rockwell B)
  • Ultimate Tensile Strength (Metric) – 560 MPa
  • Yield Tensile Strength (Metric) – 460 MPa
  • Modulus of Elasticity (Metric) – 190-210 GPa
  • Machinability – 70% (in annealed state)



  • Has the ability to withstand high mechanical stress
  • Can undergo tremendous pressure
  • Can sustain in corrosive environments – it contains niobium for stabilization against sensitization and resultant ‘inter-granular corrosion’.
  • High ductility
  • High weldability
  • Possesses excellent finish
  • Good mechanical properties – at elevated & ambient temperatures.


The major applications of AISI 4130 pipes are:

  • Structural applications include aircraft engine mounts and welded tubing
  • Bicycle frames
  • For transportation of pressurized gases
  • Firearm parts
  • Car manufacturing
  • Water heaters & coolers factory
  • Nuclear power plant
  • Solar power station
  • Desalination plant
  • Choke & kill manifolds 
  • High-pressure boiler equipment
  • Pipeline end terminations
  • Subsea wellhead

AISI 4130 seamless pipes are popularly used due to it’s many advantages but mainly because they respond to mechanical as well as heat treatments better than carbon steels.

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Things to know about AISI 4130 Seamless Pipe

by admin time to read: 1 min