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Looking for carbon steel but confused between 1018 and 4018 steel? We are here to help you out!
For high-strength and heavy-duty applications, 4140 steel is more suitable than 1018. However, if your main concern is machinability and welding, go for 1018 steel.
Want to learn more? Go through the below similarities and dissimilarities to pick the best steel between 1018 and 4140:
What is 1018 Steel?
1018 steel or AISI 1018 is low-carbon mild steel. If we define the numbers, ‘10’ stands for 10xx series of carbon steels as categorized by AISI (American Iron and Steel Institute). The last 2 digit, ‘18’, defines its carbon content as 0.18% (approx).
1018 steel is not so hard, which makes it an excellent metal for machining and welding. You can shape it into a complex structure, and it is highly suitable for general application. Besides, they have excellent weldability and mechanical properties.
What Is 4140 Steel?
4140 has more carbon content than 1018 steel. This increases the robustness and strength of the steel. The first two digits, ‘41’, define the steel as under the AISI 41xx series, and the later two digits, ‘40’, indicate its carbon content of 0.40% (approx).
Due to increased carbon content, you can use 4140 steel for heavy-duty applications. Besides carbon, it also contains chromium, molybdenum, magnesium, etc. The presence of these alloying elements hardens and boosts the strength of 4140 steel.
Comparison Chart: 1018 vs 4140 Steel (Overview)
| Property | 1018 steel | 4140 steel |
|---|---|---|
| Type | Low-carbon steel | Low-alloy steel |
| Main Alloying Elements | Manganese | Chromium, Molybdenum, Manganese |
| Strength | Moderate | High |
| Hardness | Moderate | High |
| Ductility | High (excellent for cold-forming) | Moderate |
| Heat Treatment Ability | Limited | Excellent |
| Machinability | Excellent | Good after annealing |
| Weldability | High | Moderate |
| Corrosion Resistance | Low | Low (slightly higher than 1018 steel) |
| Cost | Lower | Higher |
| Application | General applications, like- precision parts, fasteners, and frames | Heavy-duty applications, like- shafts, gears, and high-stress components. |
1018 vs. 4140 Steel: In-depth Comparison
Composition and Alloying Elements
Both 1018 and 4140 steel have the majority of iron (Fe) in their chemical composition. Comparing the alloying elements, 4140 contains more alloying elements than 1018. Besides, 4140 steel has greater carbon content than 1018 steel.
Additionally, the presence of additional elements like chromium, silicon, and molybdenum makes 4140 more robust and corrosion-resistant. In contrast, 1018 steel lacks these alloying elements.
| Alloying Element | Symbol | 1018 steel | 4140 steel |
|---|---|---|---|
| Carbon | C | 0.15% – 0.20% | 0.380% – 0.430% |
| Phosphorous | P | 0.04% (max) | 0.035% |
| Manganese | Mn | 0.60% – 0.90% | 0.75% – 1.0% |
| Sulfur | S | 0.05% (max) | 0.040% |
| Chromium | Cr | – | 0.80% – 1.10% |
| Iron | Fe | Balance | Balance |
| Silicon | Si | – | 0.15% – 0.30% |
| Molybdenum | Mo | – | 0.15% – 0.25% |
Mechanical Properties
Compared to 1018 steel, 4140 steel has a tensile strength that is roughly 1.49 times higher. If you need a robust solution, 4140 steel is more suitable. Besides, due to higher elongation at break, you can shape and bend 4140 steel with greater flexibility.
| Features | 1018 steel | 4140 steel |
|---|---|---|
| Poisson’s ratio | 0.29 | 0.27-0.30 |
| Tensile strength | 440 MPa | 655 MPa |
| Elongation at break (in 50 mm) | 15% | 25.70% |
| Yield strength | 370 MPa | 415 MPa |
| Modulus of elasticity | 205 GPa | 190-210 GPa |
| Shear modulus | 80 GPa | 80 GPa |
Thermal Properties
The thermal properties of 1018 and 4140 steel are quite similar. They share the same melting properties. However, there are differences in their thermal conductivity. 1018 steel has a thermal conductivity of 51.9 W/mK, which is much higher than 42.6 W/mK of 4140 steel.
This makes 1018 more suitable for applications where efficient heat dissipation and minimal thermal expansion are needed. In contrast, 4140 steel is great for applications that deal with heat treatment to increase strength.
| Thermal & Electrical Features | 1018 steel | 4140 steel |
|---|---|---|
| Thermal Expansion Coefficient | 12 µm/m-K | 12.2 µm/m°C |
| Thermal Conductivity | 51.9 W/mK | 42.6 W/mK |
| Melting Onset (Solidus) | 1420°C | 1420°C |
| Melting Completion (Liquidus) | 1460°C | 1460°C |
Electrical Characteristics
1018 steel has lower electrical resistance than 4140 steel. That is, electricity flow in 1018 is smoother in 1018 as it faces less hindrance. Thus, it has better electrical conductivity than 4140 steel. So, if your application deals with electrical conduction, choose 1018 steel.
| Characteristics | 1018 steel | 4140 steel |
|---|---|---|
| Electrical Resistivity | 1.590×10^{-7} ohm-m | 2.200×10^{-7}ohm-m |
| Electrical Conductivity (% IACS) | 10.84% IACS | 7.84% IACS |
Machinability and Weldability
The machinability of the steel is related to its carbon content. As 1018 has a lower carbon content than 4140 steel, it’s soft and easy to work with. This feature makes 1018 more machinable than 4140 steel. You can shape its complex structure and also weld it with ease.
In contrast, welding and machining is challenging with 4140 steel. You need to go through a preheating procedure before welding, which increases manufacturing costs.
Hardness
4140 steel exceeds 1018 Steel in all types of hardness tests. The Brinell hardness test shows that 4140 steel has a hardness value of 197 kgf/mm². In comparison, 1018 steel is softer, with a hardness of only 126 kgf/mm². Thus, you can see the difference is huge. So, considering robustness and hardness, 4140 steel wins the race.
| Hardness Test | 1018 steel | 4140 steel |
|---|---|---|
| Brinell Hardness (BHN) | 126 kgf/mm² | 197 kgf/mm² |
| Knoop Hardness (KHN) | 145 kgf/mm² | 219 kgf/mm² |
| Rockwell B Hardness (HRB) | 71 HRB | 92 HRB |
| Vickers Hardness (VHN) | 131 kgf/mm² | 207 kgf/mm² |
Corrosion Resistance
1018 steel has poor resistance against corrosion. So, it’s not quite suitable for applications that consciously deal with moisture. In contrast, a 0.80% – 1.10% chromium content in 4140 contributes to providing corrosion resistance. The addition of molybdenum also extends its anti-rust resistance features.
However, compared to stainless steel, the corrosion resistance of 4140 steel is nothing significant. It requires plating, coating, and other measures to stay protected in an excessively rust-prone environment.
Application
The application of the steel depends on its physical and mechanical properties. Due to the softer and lower strength of 1018 steel, it is mostly used for general applications. For example:
- Shafts, pins, and couplings
- bolts, screws, and studs
- Furniture frames
- Lawn equipment parts
- Bicycle frames
- Plows and harvester components, etc.
Likewise, you can use this steel for applications dealing with low stress.
In contrast, high tensile strength and hardness make 4140 steel suitable for heavy-duty applications. It is widely used in machinery parts, aerospace, automobiles, etc. Besides, you can also use 4140 steel for any high-stress components, for instance:
- Bearings
- Crankshafts
- Dies, molds, punches
- Automotive axles, trailer axles, and axle shafts
- Gears for heavy machinery
- Aerospace fasteners, etc.
Price
As 4140 has more alloying elements, it is naturally more expensive than 1018 steel. It has chromium, molybdenum, and silicon as additional elements, which increases its cost. So, comparing prices, 1018 steel is more affordable, but if you want strength, spending the extra money on 4140 is worth it.
Advantages
Pros of 1018 Steel
- Ease of fabrication
- Cost-effective
- Widely available
- Good machinability & weldability
- Moderate strength and good ductility
- Support cold-forming processes
- Ideal for non-critical applications requiring moderate strength
Pros of 4140 Steel
- High tensile strength
- High wear resistance
- Good fatigue resistance
- Suitable for high-stress applications
- More corrosion resistant than 1018 steel
- Enhanced mechanical properties after heat treatment
Disadvantage
Pros of 1018 Steel
- Lower strength
- Limited wear resistance
- Prone to corrosion
- Not suitable for heavy-duty or high-stress application
Pros of 4140 Steel
- Welding is challenging
- Needs heat treatment for optimal performance
- Prone to cracking
- More expensive than 1018 steel
What Are The Similarities Between 1018 and 4140 Steel?
Both 1018 and 4140 steel are carbon steel. They support machining welding and can go through heat treatment to boost strength. Besides, 1018 and 4140 steel have comparable thermal energy storage capabilities. This is because they share the same specific heat capacity of approximately 470 J/kg-K.
1018 Steel vs 4140 Steel: Which One is Best for Your Application?
Consider Your Application Needs
To choose the appropriate steel, you must consider its application. If the material needs to go through high stress and take heavy loads, go with 4140 steel. It has higher tensile strength to back up heavy-duty applications. For example, gear for heavy vehicles, aerospace fasteners, etc.
However, for better welding and machining, 1018 steel is better than 4140. Welding 1018 is easy, requiring no additional heat treatment. This will reduce your manufacturing cost by many times.
Long Term Performance
Though 4140 steel requires more upfront cost, in the long run, it can be a win-win solution due to its high durability. Besides, it will also reduce your maintenance and replacement costs.
Customized Mechanical Properties
Both 1018 and 4140 steel supports heat treatment. However, if you need customized mechanical properties, 4140 will give better results. It responds to heat treatments like quenching and tempering, which is excellent. On the other hand, the heat treatment on 1018 is not very effective.
Working Environment
If your application deals with harsh environmental conditions, 4140 is a more durable option. It can defend against potential stress and heavy loads. Besides, it is also more corrosion-resistant compared to 1018.
Budget
Budget is a crucial factor for manufacturing any item. If you are on a tight budget, 1018 is a cheaper option. It requires fewer alloying elements, reducing your overall investment. On the other hand, 4140 deals with several additional elements and, in some cases, also needs heat treatment for strengthening. All this makes 4140 much more expensive than 1018 steel.
However, if you are willing to spend more to fit application needs and greater strength, go with 4140 steel.
Get Expert Consultation
For industrial-level applications, you must not hesitate to consult experts. Experts will analyze your application needs, temperature, load-bearing capacity, and other factors to pick the right one between 1018 and 4014.
Conclusion
When choosing between 1018 and 4140 steel, the foremost thing to consider is their application. 4140 has high tensile strength and hardness, which makes it suitable for heavy-duty applications. You can also boost its toughness through heat treatment. In contrast, 1018 is soft but has greater machinability. So, if you require more flexibility in shaping and forming, 1018 gives better results.
However, for CNC machining 1018 and 4140 steel, RICHCONN is your go-to option. We offer machining for automotive parts, industrial machinery, tools, and other structural components. Contact us ASAP to get a consultation for your project!
FAQs
What are the suitable heat treatments for 4140 steel?
4140 steel supports a wide range of heart treatments, including annealing, quenching, tempering, case hardening, etc.
Which is more soft and brittle: 1018 or 4140 steel?
Due to low carbon content, 1018 steel is more soft and brittle than 4140. So, if you need hardness, 4140 steel is the go-to option.
Is 4140 a carbon steel?
Yes, 4140 is a carbon steel with moderate carbon content. It contains about 0.380% to 0.430% carbon.
What is heat-treated 4140 steel?
Heat-treated 4140 steel means the steel has been heat-treated to enhance its strength, toughness, and wear resistance. Such steels are suitable for heavy-duty applications.
Is a pre-hardened 4140 steel hard enough?
As per the Rockwell Hardness C scale, the hardness of pre-hardened 4140 steel usually ranges from 28 to 32 HRC.
