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 steel 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 mechanical 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