What is 4130 Alloy Steel & Steel 4130 Properties, Uses | 4130 Steel vs 4140 | CNCLATHING


Steel is the structural material of the construction and transportation industry on the earth. Its alloy elements give it many excellent characteristics, and also derive a variety of types. Based on the designation system represented by AISI and SAE, we typically use a four-digit number to name different alloy steels. What we’ll outline in this post is 4130 alloy steel, from its detailed composition and fabrication characteristics, to 4130 steel properties and uses, as well as AISI 4130 steel vs 4140.

What is 4130 Alloy Steel?

4130 steel (AISI/SAE 4130) is chromium-molybdenum steel with 1% molybdenum/chromium by mass with an included 0.30% carbon. The name of alloy steel are designated by AISI and SAE using a four-digit number, the first digit indicates the class of steel, including its major alloying elements, the second digit shows the relative percentage of this alloying element and/or other important secondary elements and last two digits mean the carbon concentration in 0.01% increments. 4130 Alloy steel is low-alloy steel that has good strength, toughness, weldability and machinability, as well as good atmospheric corrosion resistance. 

When it comes to manufacturing and processing of 4130, AISI 4130 steel is weldable in all commercial methods, and readily machined in its normalized/tempered condition, CNC machining services for 4140, 4130, A36, 1018 and more steel alloys are available at Junying. Forming of SAE 4130 grade can be performed in the annealed condition, it can be annealed at 843°C. Forging of 4130 steel can be performed at 954 to 1204°C. Hardening of AISI 4130 alloy steel can be done with cold working or heat treatment, the cold working can be done using conventional methods and hot working can be done at 816 to 1093°C. And tempering of 4130 steel can be performed at 399 to 566°C. The temperature for alloy 4130 heat treatment usually ranging from 899 to 927°C. 


Check out the breakdown of 4130 steel composition:

C (Carbon): 0.28% – 0.33%

Mn (Manganese): 0.40% – 0.60%

P (Phosphorus): 0.035% max

S (Sulfur): 0.040% max

Si (Silicon) 0.20% – 0.35%

Cr (Chromium): 0.80% – 1.10%

Mo (Molybdenum): 0.15% – 0.25%

4130 Steel Properties

Physical Properties of AISI 4130 Steel

Density of 4130 Alloy Steel: 7.85 g/cm3 (0.284 lb/in³)

Melting Point of Steel 4130: 1432°C (2610°F)


Mechanical Properties of AISI 4130 Steel

Brinell Hardness of 4130 Steel: 217

Rockwell B Hardness of 4130 Steel: 95

Rockwell C Hardness of 4130 Steel: 17

Vickers Hardness of 4130 Steel: 228

Ultimate Tensile Strength of 4130 Steel: 560 MPa (81200 psi)

Yield Tensile Strength of 4130 Steel: 460 MPa (66700 psi)

Modulus of elasticity: 190-210 GPa (27557-30457 ksi)

Elongation at break (in 50 mm): 21.50%

What is 4130 Steel Used for?

4130 alloy steel is known as its strength when it is used for heat treatment, it performs best as structural steel, high toughness and low alloy material make it work well for welding, cutting and manufacturing of aircraft parts and other industries. Steel 4130 also finds its uses as forgings in oil & gas fields, made as forged valve bodies and pumps, as well as automobile, agricultural and defense industries. Common applications of 4130 steel including:

– Ball and roller bearings

– Gears for aerospace and other industries

– Automotive parts, vehicle parts and rock crushing machinery

– Structural parts like round tubes or bar stock

– Cutting tools like drills, taps, milling cutters, etc.

– Resistance welding 

4130 Steel vs 4140 - What’s the Difference Between 4130 Steel and 4140

4140 is similar to 4130 alloy steel except for the carbon content, which we can find from the last two digits, The “40” in 4140 represents higher content of carbon than that in 4130, the difference in composition also makes their properties difference. Below are the details.

1. Composition

4130 contains 0.28-0.33% Carbon and 0.40-0.60% Manganese, while 4140 contains 0.75-1.00% Manganese and 0.38-0.43% Carbon.

2. Characteristics and performance

– 4140 alloy steel has greater hardenability and strength than 4130.

– 4130 steel is easier welding than AISI 4140 steel and its wear-resistant performance is lower than in 4140.

3. Mechanical properties

Difference in mechanical properties for normalized 4130 and 4140 steel

Difference in mechanical properties for annealed 4130 and 4140 steel

4. Availability

4140 is typically more readily available and more cost-efficient in bar and plate forms, while 4130 is more commonly obtained in tube and sheet forms.


5. Machinability

Based on SAE1212 as 100% machinability, the relative machinability of AISI 4130 steel is 70% and 4140 is 65%.