Comparing the Attributes of 4130 and 4340 Grade Steel

Types 4130 and 4340 steel are popular grades used in fabrication and machining applications. Various configurations of both grades such as tubing, plates, sheets, as well as round and rectangular bars, are used to machine or fabricate components. So how do you determine which grade is most suited for your machining needs? In this post, we answer this question by comparing the various attributes of both grades.

4130 vs. 4340 Steel Grade Descriptions

Following are general descriptions of both steel grades:

  • 4130 Grade Steel: This alloy of steel is often referred to as Chromoly, as it contains high amounts of chromium. The general characteristics of 4130 grade steel include exceptional ductility, machinability, strength, and weldability. It is used in various industries such as automotive, aerospace, textile, and more.
  • 4340 Grade Steel: This alloy of steel is known for its immense strength, which is due to a high concentration of nickel-chromium-molybdenum. It is sought after for its toughness and high stress bearing qualities. Grade 4340 steel plates are used in a variety of industries for different applications including aircraft landing gear, power transmission gears and shafts, and other structural parts.

Comparison of Different Attributes of 4130 and 4340 Grade Steel

Below is a comparison of the chemical and mechanical properties of both grades. It will help you understand the properties of each grade, thus allowing you to purchase the right type for your application.

Chemical Properties of 4130 and 4340 Grade Steel

The chemical properties of 4130 and 4340 steel have different concentrations of carbon, manganese, and chromium:

Typical Chemical Composition in %
Grade Carbon C Manganese Mn Silicon Si Phosphorus P Sulfur S Chromium Cr Molybdenum Mo
4130 0.30 0.40 – 0.60 0.15 – 0.35 0.035 0.040 0.80 – 1.10 0.15 – 0.25
4340 0.40 0.60 – 0.80 0.15 – 0.30 0.035 0.040 0.70 – 0.90 0.20 – 0.30

Mechanical Properties of 4130 and 4340 Steel

The following are the mechanical properties of 4130 and 4340 grade steel for both normalized and annealed varieties:

Normalized Mechanical Properties of 4130 and 4340 Grade Steel
Grade Tensile Strength PSI Yield Strength 0.2% Offset PSI Elongation % in 2ʺ(50.8 mm) Hardness
(Brinell) MAX
Reduction in Area %
4130 97,000 63,000 25.5 197 59.5
4340 185,500 125,000 12.2 363 36.3
Annealed Mechanical Properties of 4130 and 4340 Grade Steel
Grade Tensile Strength PSI Yield Strength 0.2% Offset PSI Elongation % in 2ʺ(50.8 mm) Hardness
(Brinell) MAX
Reduction in Area %
4130 81,300 52,300 28.2 156 55.6
4340 108,000 68,500 22.0 217 49.9

The relative machinability rating for cold drawn 4130 and 4340 grade steel is based on SAE 1212 as 100%. It is expressed as follows:

  • 4130 Grade Steel – 70%
  • 4340 Grade Steel – 50%

It is evident from the above mentioned tables that both grades of steel possess different chemical and mechanical properties. Thus, their areas of application are also different. If you need any help in choosing the grade as per your requirements, it is best to contact a manufacturer or supplier of steel products like pipes, tubes, sheets, and plates.