4130 vs 4340 Steel Comparison

4130 and 4340 are both popular steel grades at Capital Steel & Wire. Below is a chemical and mechanical properties comparison of both grades of steel as it may be of value for machining purposes and as a resource for purchasing 4130 and 4340 steel.

4130

This low alloy steel contains high amounts of chromium and is often referred to as chromoly. 4130 steel has good machinability, ductility, weldability and strength characteristics. It is used for many different industries including the automotive, aerospace and machining industries.

4340 

This nickel-chromium-molybdenum alloy streel is a very high strength steel. It is sought after for its toughness and for being used as a steel that will be highly stressed.

It is used in a variety of industries for different applications including the automotive, aerospace, and tooling industries. 

Chemical Properties

The chemical properties of 4130 and 4140 steel have differences in carbon, manganese and chromium concentrations.

  4130 4340
Carbon, C 0.30% 0.40%
Manganese, Mn 0.40-0.60% 0.60-0.80%
Chromium, Cr 0.80-1.10% 0.70-0.90%
Molybdenum, Mo 0.15-0.25% 0.20-0.30%
Silicon, Si 0.15-0.35% 0.15-0.30%
Phosphorus, P (max) 0.035% 0.035%
Sulfur, S (max) 0.040% 0.040%

Mechanical Properties

 The following are the mechnical properties for both normalized and annealed 4130 and 4340 steel.

Normalized

  4130 4340
Tensile Strength 97,000 psi 185,500 psi
Yield Strength 63,000 psi 125,000 psi
Elongation (2") 25.5% 12.2%
Reduction in Area 59.5% 36.3%
Brinell Hardness 197 363

Annealed

  4130 4340
Tensile Strength 81,300 psi 108,000 psi
Yield Strength 52,300 psi 68,500 psi
Elongation (2") 28.2% 22.0%
Reduction in Area 55.6% 49.9%
Brinell Hardness 156 217

The relative machinability Rating percentage based on SAE1212 as 100% is the following for cold drawn 4130 and cold drawn 4340 steel

  • 4130 - 70%
  • 4340 - 50%

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