ThePipingMart Blog Grades SAE/AISI 5120 Alloy Steel – Composition, Properties and Uses

SAE/AISI 5120 Alloy Steel – Composition, Properties and Uses

SAE/AISI 5120 Steel

SAE/AISI 5120 steel is a medium carbon alloy steel used in a wide array of applications. This steel is known for its impressive machinability, strength, and cost-effectiveness. In this blog post, we’ll take a closer look at the uses, corrosion resistance, heat resistance, heat treatment process, machining process, and welding process of SAE/AISI 5120 steel.

AISI 5120 Composition

Element Weight %
C  0.17-0.22
Mn  0.70-0.90
P  0.035 (max)
S  0.04 (max)
Si  0.15-0.30
Cr  0.70-0.90

AISI 5120 Physical Properties

AISI 5120 is a very versatile chromium-manganese-molybdenum alloy steel that is often used when strength and toughness are key requirements. It has excellent machinability properties and can be worked into various shapes, such as bars, rods, tubes and wire with ease. As a result of its excellent strength, it has been used in automotive applications over the years, though its most common use is in the manufacture of gears for larger machinery and machine tools. Additionally, due to its good wear resistance it can also be found in many industrial parts subject to abrasion or wear. AISI 5120 offers tremendous versatility thanks to these physical properties and makes an attractive choice for many applications requiring strength and durability.

AISI 5120 Mechanical Properties

Properties  Conditions
T (°C) Treatment
Density (×1000 kg/m3) 7.7-8.03 25
Poisson’s Ratio 0.27-0.30 25
Elastic Modulus (GPa) 190-210 25

AISI 5120 Equivalent

  • ASTM A322
  • ASTM A331
  • ASTM A519
  • SAE J404
  • SAE J770
  • UNS G51200

AISI 5120 Uses

SAE/AISI 5120 steel is used in many industries, including the automotive industry, where it is used to make parts like gears and shafts, as well as construction and agriculture, where it can be found in farm equipment. This type of steel is also commonly used in industrial machinery such as conveyor belts and pumps due to its high strength and durability.

Corrosion Resistance

SAE/AISI 5120 steel has excellent corrosion resistance, making it ideal for use in wet environments or areas with higher levels of humidity. It resists both acidic and alkaline solutions, which makes it an ideal choice for industrial applications that require exposure to corrosive elements. The addition of chromium makes this type of steel even more resistant to corrosion so that it can withstand long-term use without becoming damaged or weakened.

Heat Resistance

SAE/AISI 5120 has excellent heat resistance, which makes it ideal for applications that involve high temperatures. It can withstand temperatures up to 650°C (1200°F) without losing its strength or becoming brittle. This makes it an excellent choice for hot working processes such as forging or welding applications.

Heat Treatment

SAE/AISI 5120 steel can be easily heat treated through normalizing or annealing processes depending on the desired results. Normalizing involves heating the material until it reaches approximately 860°C (1580°F), then allowing the material to cool slowly at room temperature until it reaches ambient temperature, whereas annealing involves heating the material until it reaches approximately 790°C (1450°F). Both processes help improve the material’s ductility while still retaining its strength properties.


SAE/AISI 5120 has excellent machinability, making it easy to work using standard machine tools like lathes and milling machines. It does not require any special cutting tools or techniques or additional cooling during operation due to its low carbon content, which helps reduce warping when machining large components from this material.


Welding SAE / AISI 5120 requires preheating before welding because this material has a high melting point (around 1360°C). Preheating helps prevent cracking during welding by reducing thermal stresses on the welded joint itself; however, welding should always be done using low current settings so as not to overheat the metal, which could lead to porosity issues within the weld itself.


In conclusion, SAE / AISI5 120 offers superior strength at an affordable cost while exhibiting excellent corrosion resistance and exceptional machinability properties – making this type of steel ideal for many industrial applications such as those involving automotive parts production, construction projects, and agricultural equipment manufacturing among others – all thanks to its unique combination of chemical composition and physical characteristics! Additionally, its ability to be easily heat treated through normalizing or annealing processes and its simple weldability make this versatile metal suitable for use in almost any situation requiring a strong yet lightweight material. With all these features combined, it’s no wonder why SAE / AISI5 120 is quickly becoming one popular choice among manufacturers across various industries today!

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SAE/AISI 5120 Alloy Steel – Composition, Properties and Uses

by Abhishek Modak time to read: 3 min