As we all know, AISI 4130 steel is widely used in many fields, such as aerospace, automobile, agriculture and defense industry, especially in the oil and gas industry which can be seen everywhere.We will try to unveil the popular veil of AISI 4130 steel application in the industry, so as to further understand its characteristics.

Through this guide, we believe that you not only have the ability to identify high-quality AISI 4130 steel, but also you can find the best way to purchase the best quality of 4130 steel in the market!

AISI 4130 Forged steel with QT condition


We explained the meaning of many American grades in the “How to” series on the FAQ&BLOG page, such as similar AISI 4140 steel and AISI 4340 steel, so please come and try to analyze the meaning contained in AISI 4130 steel.

The first two digits in the steel number generally indicate the type of steel,while the last two digits indicate the amount of carbon present in the steel.We can see the below structure diagram From AISI/SAE Steel Designation System,and we can find UNS  G41300, it is the number for 4130 steel.

AISI Designation

From the above, we can clearly know that the last two “30” in 4130 represent an average carbon content of 0.30%.For the specific meaning of the first two digits in AISI 4130 steel, we can see the following table.

Molybdenum Steel
40XXMo 0.20-0.25%
44XXMo 0.40-0.52%
Chromium-Molybdenum Steel41XXCr 0.50-0.95%, Mo 0.12-0.30%

Nickel-Chromium-Molybdenum Steel
43XXNi 1.82%, Cr 0.50-0.80%, Mo 0.25%
47XXNi 1.05%, Cr 0.45%, Mo 0.20-0.35%

Nickel-Molybdenum Steel
46XXNi 0.85-1.82%, Mo 0.20-0.25%
48XXNi 3.50%, Mo 0.25%


First of all, if we want to clarify this question, let’s take a look at their respective origins.AISI 4130 is a grade from ASTM A29 American standard, while 30CrMo comes from Chinese GB 3077 standard. They can be said to be similar grades. Let’s take a look at their specific composition differences, please see the table below.

ASTM A2941300.28-0.330.15-0.350.4-0.6≤0.035≤0.040.8-1.10.15-0.25
GB 307730CrMo 0.26-0.33 0.17-0.370.4-0.7 ≤0.03 ≤0.030.8-1.10.15-0.25

From the above table,we can intuitively see their small differences, which are so small that they can be ignored.In actual use, we can completely replace each other, of course, the premise is to carefully check whether their chemical composition is in the overlapping range.

Other Equivalent Grade

Europe/EN10083 &EN10250:25CrMo4/DIN 1.7218

Japan/JIS G4105:SCM430



Is AISI 4130 Steel Low-Carbon Low-Alloy Steel?

From the above content,we can clearly see that AISI 4130 has carbon content with range 0.28-0.33%.According to the classification of carbon content, it belongs to the Medium-carbon series( 0.25%≤ C<0.6%).With Alloy elements below 5%,we can define AISI 4130 as low alloy steel.

Can AISI 4130 Steel be Cold Drawn?

Yes,AISI 4130 steel can be cold drawn with high-precision size and smooth surface.After cold drawn process,AISI 4130 steel has good mechanical properties and can be directly applied without further processing.

In addition to cold-drawn round steel, AISI 4130 can also be processed into other shapes, such as square steel, flat steel, hexagonal steel, and even special-shaped steel.

AISI 4130 cold drawn round steel

Can AISI 4130 Steel be Nitrided?

Yes,as the 4130 steel in the AISI 41XX series of medium-carbon low-alloy steels, it contains Cr and Mo elements, which can form stable nitrides by nitrogen atoms and improve the nitriding effect.

After nitriding, AISI 4130 steel has significantly improved wear resistance, surface hardness, fatigue limit and corrosion resistance.

How Hard is AISI 4130 Steel?

AISI 4130, as a steel for petroleum and petrochemicals, is usually used after quenching and tempering, with high strength and toughness. According to the requirements of API 6A, the hardness is generally between 197-237HBW, which is the requirement of AISI 4130 75K.

The application of higher hardness of AISI 4130 steel can be achieved by nitriding,it can get surface hardness 550-700HV3,with nitration hardness depth 0.2-0.7mm.

AISI 4130 Steel vs AISI 4135 Steel

As a Cr-Mo series alloy structural steel,AISI 4130 and AISI 4135 belong to the ASTM A29 standard.First of all, let’s take a look at their specific composition differences.


From the above table,the carbon content of AISI 4135 is higher than 4130, so the hardness, tensile strength and yield strength of AISI 4135 are relatively better for the two materials after heat treatment. However, AISI 4130 is better in terms of toughness.

According to the classification of API temperature grade, 4135 and 4130 steel are often applied to P-U grade, which is -29℃—+121℃. However, due to the slightly lower carbon content of 4130 steel, its low temperature performance is slightly better than that of 4135 steel.(the difference is also relatively speaking, basically the difference is not very large).


We analyze AISI 4130 and AISI 4140 from the naming rules of American steel grades.The most sure thing is that they belong to Chromium-Molybdenum Steel.Then let’s take a concrete look at their performance differences in various aspects.

  • Chemical Composition

From the above table,we can clearly see that, as Cr-Mo series alloy steels, AISI 4130 and AISI 4140 have the same content of Cr and Mo elements, but the difference is obvious in C and Mn elements.

  • Heat Treatment
Quenching MediumOil/WaterOil/Water

aisi 4140 forged flat steel with QT condition

AISI 4140 forged flat steel with QT condition

  • Mechanical Property

Normalizing Mechanical Property Comparison

GradeTensile Strength Yield StrengthElongationReduction of Area Impact Charpy-V Hardness

Annealing Mechanical Property Comparison

GradeTensile Strength Yield StrengthElongationReduction of Area Impact Charpy-V Hardness

Quenching&Tempering Mechanical Property Comparison

GradeTensile Strength Yield StrengthElongationReduction of Area Impact Charpy-V
  • Weldability

According to the carbon equivalent formula,CE=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15.

Carbon equivalent (CE)Weldability
0.36–0.40Very good

we probably calculated that the CE of AISI 4140 is around 0.8, while AISI 4130 has a CE of around 0.6.From the above table,we can know that the weldability of both materials is poor.But in comparison, AISI 4130 is relatively easy to weld due to its low carbon content.

The preheating process before welding is very necessary for both, especially AISI 4140 steel with high carbon content, which can effectively prevent welding cracks.The implementation of post-weld heat treatment(PWHT) is also very necessary for the two materials,which can effectively release the welding stress and prevent the appearance of cracks.

  • Hardenability

The hardenability is mainly affected by the chemical composition, and the most influential element is carbon. When the C% is less than 1.2%, as the carbon concentration in austenite increases, the critical cooling rate is significantly reduced, and the hardenability of the steel is increased.

The second is alloying elements. Except for cobalt, most of the alloying elements dissolve into austenite to reduce the critical cooling rate, thereby improving the hardenability of steel.

From the above chemical composition comparison, it can be seen that the carbon content of AISI 4140 is significantly higher than that of AISI 4130.In addition, the Mn content of AISI 4140 is also higher than that of AISI 4130, and the Mn element plays a certain role in improving the hardenability.Through comprehensive comparison, the hardenability of AISI 4140 is relatively higher.


As a petroleum and petrochemical steel, AISI4130 material is widely used in the field of petroleum and natural gas.We must strictly implement the standards of this industry, of which API 6A is the most widely used.Next, we will discuss the specific requirements of AISI 4130 steel 75K in the API 6A standard.

AISI 4130 75K Requirement

Material Designation0.2% Offset yield strength
Tensile strength
Elongation in 50 mm (2 in)
Reduction in Area

The above is the specific requirements of AISI 75K material in API 6A, so how to achieve it, we have to start with composition and process control, and implement it step by step.

  • Melting Method

Steelmaking can be carried out through an electric furnace process with continuous xenon oxygen removal (AOD) or vacuum treatment (EFVD), as well as vacuum induction remelting (VIM), vacuum arc remelting (VAR), or electric furnace slag remelting (ESR) shall also be acceptable.

  • Chemical Composition

It is obviously not enough to require the chemical composition of AISI 4130 in accordance with the ASTM A29 standard. We need to adjust the lower limit of its alloy composition and effectively control harmful elements according to the following table.

ASTM A290.28-0.330.15-0.350.4-0.6≤0.035≤0.040.8-1.10.15-0.25
Adjustment for API 6A0.28-0.330.15-0.350.4-0.6≤0.025≤0.0251.0-1.10.2-0.25

We must at least increase the alloying elements above the midline, and control the P/S harmful elements below 0.025% or even lower according to the PSL 3 level (PSL 4: P≤0.015%, S≤0.01%)

  • Hot Forging

Forging can apply pressure to AISI 4130 material to produce plastic deformation to obtain certain mechanical properties. Through a suitable forging process, it can eliminate defects such as as-cast looseness of the material during the smelting process, optimize the microstructure and improve performance.

According to API requirements, we need to ensure that AISI 4130 has a suitable forging ratio, at least 4:1 or greater.

Forging aisi 4130 steel shaft

Forging AISI 4130 steel shaft

  • Heat Treatment

As the last process, heat treatment is very important for 4130 materials to meet the requirements of 75K. According to the requirements of API 6A, AISI 4130 steel should be normalized(N), quenched(Q) and tempered(T), that is, N+Q&T.The specific requirements are shown in the table below

Normalizing870-900℃0.5hr/inch of metal thickness
Air cool to room temperature
Quenching870-890℃0.5hr/inch of metal thicknessWater or Oil/Polymer
Tempering650-700℃0.5hr/inch of metal thicknessAir cool to room temperature

Note 1:The austenitizing temperature shall be less than the normalizing temperature.

Note 2:Water is the preferred quenching medium for all 4130 steel parts,however,oil or polymer may be used for parts whose section thickness is 6″or smaller.

Note 3:Cooling media temperature shall not exceed 38℃ at the start of the quench, and for bath type quenching the temperature of the bath at the end of the quench shall not exceed 49℃.


It is not difficult to find AISI 4130 steel in the market, but manufacturers who have API certification and can make high-quality AISI 4130 steel are hard to find. Fortunately, Halden steel can provide what you want.

Here, you can not only find any shape you want, but also you don’t have to worry about the quality of AISI 4130. We are proud that the quality of Halden can withstand the inspection of many customers.


AISI 4130 Steel Forged products


What We Supply For AISI 4130 Steel

  • Hot Rolled Round Bar:Φ20-Φ350mm,7 Days Delivery
  • Hot Forged Round Bar:Φ140-Φ250mm,15 days Delivery
  • Customized service:Special Size & Length,30 days Delivery
  • Free Sample of AISI 4130 Steel

In addition to providing AISI 4130 steel,we also have a large inventory of high-quality AISI 4140 steel, 34CrNiMo6 steel, 30CrNiMo8 steel, AISI 4340 steel, and AISI 8620 steel.Halden Steel will never fail in providing the best and the highest quality special steel for you!