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AISI 4140 vs 4142 Steel: Properties Comparision
- John
AISI 4140 and AISI 4142 are both alloy steels with similar properties. The main difference is that 4142 has slightly more carbon and small amounts of boron, which improves its wear resistance and hardenability compared to 4140. While both steels are used in similar applications, 4142 is more appropriate for uses that demand superior strength and endurance.
If you need more details about these differences, SteelPro Group, as a professional supplier, is here to provide deeper insights and help you with your needs.
Overview of 4140 and 4142 Steel
4140 Steel
AISI 4140 steel is a type of low-alloy steel made up of carbon, chromium, molybdenum, and manganese. These elements give it strength, toughness, wear resistance, and moderate corrosion resistance. This makes it suitable for high-stress applications where impact and repeated loading are common.
- AISI 4140 steel is used for manufacturing crankshafts, drive shafts, gears, axles, hydraulic rods, and tooling components in industries such as automotive and machinery.
4142 Steel
AISI 4142 is a low-alloy steel with higher carbon, chromium, and molybdenum content compared to 4140. This increased alloy content enhances its hardenability, enabling it to achieve greater strength through heat treatment. However, its higher cost and specific processing requirements make it more suitable for demanding industrial and automotive applications.
- AISI 4142 steel is primarily used for high-strength gears, crankshafts, axles, and hydraulic rods in demanding applications like automotive, aerospace, and heavy machinery.
4140 vs 4142 Chemical Composition
| Element | 4140 Steel | 4142 Steel |
| Carbon (C) | 0.38-0.43% | 0.40-0.45% |
| Chromium (Cr) | 0.80-1.10% | 0.80-1.10% |
| Manganese (Mn) | 0.75-1.00% | 0.75-1.00% |
| Molybdenum (Mo) | 0.15-0.25% | 0.20-0.30% |
| Silicon (Si) | 0.15-0.35% | 0.15-0.35% |
| Boron (B) | – | 0.001-0.005% |
Carbon Content
4142 steel has a slightly higher carbon content (0.40-0.45%) compared to 4140 steel (0.38-0.43%). This promotes the formation of harder microstructures, such as cementite, during heat treatment, improving its hardness and strength.
Molybdenum Content
The 4142 steel has a slightly higher molybdenum content (0.20-0.30%) than the 4140 steel (0.15-0.25%), which helps improve hardenability by allowing the steel to harden more evenly and deeply during heat treatment. It also increases wear resistance by strengthening the steel.
Boron Content
4142 steel contains a small amount of boron (0.001-0.005%), which helps improve its hardenability during heat treatment by allowing the steel to harden more deeply and uniformly. This is not typically found in 4140 steel.
Mechanical Properties of 4140 Steel and 4142 Steel
| Property | 4140 Steel | 4142 Steel |
| Tensile Strength | 655 MPa (95,000 psi) | 690 MPa (100,000 psi) |
| Yield Strength | 415 MPa (60,000 psi) | 450 MPa (65,000 psi) |
| Elongation at Break | 20-25% | 20-25% |
| Hardness (HB) | 197 HB | 200 HB |
| Impact Toughness | 27 J (20 ft-lb) | 30 J (22 ft-lb) |
| Poisson’s Ratio | 0.29 | 0.29 |
Both 4140 and 4142 steels offer good strength, hardness, and toughness, ensuring reliable performance under moderate to high loads. They are capable of achieving substantial hardness after proper heat treatment, though 4142 tends to provide deeper hardening, especially in thicker sections.
Compared to 4240 steel, 4142 benefits from its higher carbon content and chromium, offering superior strength, hardness, and hardenability. It performs exceptionally well in applications that demand superior mechanical properties.
Advantages and Disadvantages of 4140 vs. 4142 Steel
| Steel Type | Advantages | Disadvantages |
| 4142 Steel | Higher strength, hardness, and hardenability due to increased carbon and chromium. | More expensive than 4140. |
| Better wear resistance and deeper hardening, especially in thicker sections. | Harder to machine compared to 4140. | |
| 4140 Steel | Excellent balance of strength, toughness, and machinability. | Lower hardenability and wear resistance than 4142, especially in thicker sections. |
| More cost-effective for general-purpose applications. | – |
4140 And 4142 Steel Different Applications
The applications of AISI 4140 and AISI 4142 are quite similar, as both are used in components requiring high strength, toughness, and resistance to wear. These materials are widely utilized in sectors such as automotive, aerospace, and heavy machinery. Both steels are suitable for manufacturing parts like gears, shafts, crankshafts, axles, and hydraulic rods.
However, the key distinction is in the degree of performance demanded.
AISI 4140 is more cost-effective and suitable for general-purpose applications. AISI 4142, with its higher alloy content, is used for more demanding, high-performance parts like aerospace components and heavy-duty shafts, where superior strength and wear resistance are required.
4140 and 4142 Steel Products: Tailored to Your Needs
At SteelPro Group, we offer high-quality steel products that meet the chemical composition specifications for both 4140 and 4142 steels. We provide a range of processing options, including nitriding, annealing, and more, to ensure optimal performance in your applications.
We also provide knife steels like D2. Whether you need superior strength, hardness, or wear resistance, our versatile products can be customized to suit your specific needs！
