How to Buy AISI 4140 Steel?

The most direct method to identify 4140 is to use a portable spectrometer, which can quickly and non-destructively detect the main alloying elements and their approximate content, but it cannot measure the most important non-alloy element, carbon content.

The most accurate method: laboratory wet analysis, which provides the exact percentage of all elements.

In addition, some material identification can also be done directly or indirectly by observing sparks and testing hardness.Learn More

Under the same quenching and tempering process, 4340 can achieve a higher ultimate hardness, meaning 4340 steel is harder than 4140 steel.

However, in practical applications, material selection is not simply a matter of “which is harder,” but rather should consider:

While meeting the necessary hardness/strength requirements, does the material also need higher toughness to withstand impacts? Does it need better fatigue performance to ensure lifespan? Furthermore, practical constraints such as cost, processing difficulty, and cross-sectional dimensions must also be considered.

4140 steel and 4140H steel are both Cr-Mo alloy structural steels from the same family, with essentially the same composition.

H stands for Hardenability. 4140H has mandatory requirements to guarantee hardenability, which is the core difference.Therefore, 4140H can be considered a version of 4140 with guaranteed hardenability.

Compared to 4140, 4140H represents more stable and controllable hardenability, but also implies stricter quality control and higher cost.It is more suitable for large components requiring high consistency in overall performance after heat treatment.

In API 5CT, 4140 L80 corresponds to the 80K yield strength grade defined in the API standard, which is 4140 80K.

4140 L80 steel, through quenching and tempering, achieves a balance between strength and toughness, making it a preferred material for pipes and high-pressure equipment in the oil and gas industry.The following table lists the minimum mechanical property requirement from the API standard.

4140 steel is suitable for shaft parts.

After quenching and tempering, it exhibits excellent strength-toughness balance, good hardenability, and the ability to withstand combined loads such as torsion and bending. It also possesses certain wear resistance and fatigue resistance, meeting the working requirements of medium to heavy-duty shaft components such as gear shafts, drive shafts, and machine tool spindles.

Furthermore, its machinability is controllable, facilitating subsequent turning, milling, grinding, and finishing processes.

The 4145 type of steel comes from the same family( Chromium-Molybdenum Series) of the 4140 steel.

The very small difference is their percentage of carbon content.4145 has carbon content with 0.43-0.48%,0.05% higher than 4140 Steel.Due to the slight difference in carbon content, the strength of 4145 steel is slightly higher than that of 4140 steel.

With suitable heat treatment, 4140 and 4145 steel have good comprehensive performance,and are widely used in the oil and gas industry.Learn More

4140 steel has moderate weldability and is not classified as a free-welding steel.

4140 steel contains approximately 0.4% carbon and alloying elements such as chromium and molybdenum, resulting in strong hardenability. During the welding cooling process, the heat-affected zone is prone to forming a hard and brittle martensitic structure, which easily leads to welding cracks.

Therefore, it is necessary to reduce welding risks through preheating (200~300℃), using low-hydrogen welding electrodes, and timely tempering after welding.

4140 steel is available readily machinable especially in annealed condition. The complex shapes will require annealing but simple shapes can be machined smoothly along with a normalizing treatment.

For 4140 steel after quenching and tempering, the hardness increases to 28~34HRC, increasing the difficulty of machining. However, carbide tools can still be used to complete the machining.

Relatively to carbon steel,low alloy steel is based on carbon steel,and one or more alloying elements are intentionally added to the steel to improve the properties of steel, such as strength, hardness, toughness, wear resistance, and corrosion resistanc etc.The total amount of alloying elements less than 5%,called low alloy steel.

It is no doubt that 4140 steel is a low-alloy steel that contains chromium, molybdenum and manganese alloy elements.Due to its excellent toughness, wear resistance, impact resistance and high fatigue strength, it is widely used in many industries.

Are you looking for a reliable supplier of 4140 steel products? Look no further, FUHONG will meet all your expectations.

As a professional manufacturer in the specialty steel industry, FUHONG focuses on providing reliable 4140 steel solutions for various industries. We provide every customer with traceable product quality inspection reports and a comprehensive after-sales service system. Contact us today to learn more about our products.Learn More

The core difference between the two lies in the fact that 4340 steel contains a large amount of nickel (1.65-2.0%), while 4140 steel contains no nickel. This leads to a series of differences:

• Performance: 4340 has significantly better hardenability, strength (ultra-high strength grade), and toughness (especially at low temperatures) than 4140.
• Applications: 4140 is a general-purpose high-strength material for industrial parts, while 4340 is used for ultra-high strength components operating under harsh conditions.
• Cost: Due to its nickel content, 4340 has higher raw material and processing costs.Learn More

Although 4140 steel and 4130 steel both belong to the 41xx series chromium-molybdenum alloy steels under the AISI/SAE system, they still have differences.

• Core Composition: 4130(Carbon:0.28-0.33%) < 4140(Carbon:0.38-0.43%）
• Mechanical Properties: 4140+QT has higher strength(850~1080MPa) and hardness (28~32HRC), but slightly lower toughness; while 4130+QT has lower strength (650~800MPa), but better impact toughness and plasticity.
• Processing Performance: 4130 exhibits superior weldability, cold workability, and machinability; while 4140 has slightly better hardenability and a more significant heat treatment strengthening effect, but poor in welding.
• Applications: 4130 is suitable for manufacturing structural components requiring welding and medium-strength parts subjected to impact loads (such as pipes and low-pressure vessels); while 4140 is suitable for high-strength parts requiring heat treatment strengthening (such as spindles, gear shafts, high-strength bolts, and crankshafts).

Conclusion: The core difference between 4140 steel and 4130 steel stems from their different carbon contents, leading to significant differences in strength, toughness, processing performance, and applications.Learn More

4140 steel is not corrosion-resistant. It is a medium-carbon alloy structural steel with a low chromium content (0.8-1.1%), which provides some protection, but it cannot form a stable passivation film like stainless steel.

4140 steel is prone to corrosion in humid environments, and once corrosion occurs, it will rust like most steels that suffer the same damage. The corrosion rate is even faster when exposed to acids, alkalis, and salts. Therefore, surface treatments such as blackening, electroplating, and nitriding are required to improve its corrosion resistance.

First, the conclusion is that forging significantly improves the overall mechanical properties of 4140 steel.

The raw material, 4140 steel, can be further forged to eliminate defects such as porosity and inclusions, refine grains, and obtain a uniform forged microstructure.

However, forging alone has limited effect on improving the performance of 4140 steel. Therefore, it needs to be combined with heat treatment (quenching + high-temperature tempering) to fully maximize its performance.

4140 steel generally exhibits excellent processing properties, making it suitable for various process scenarios:

• Machinability: 4140 steel is not difficult to machine.
• Hot workability:Good;suitable for forging and hot rolling.
• Cold workability:Medium;in the annealed state, 4140 steel can be cold stamped, cold bent, and cold drawn.
• Weldability: Moderate; preheating and post-weld stress relief treatment are required to prevent cracking.
• Heat Treatability: Excellent; properties can be flexibly adjusted through processes such as normalizing, quenching and tempering.