1018 vs. 4140 Steel: Comparison Guide

Steel is a very common material used in many applications. However, steel has different grades, and the two most popular ones are 1018 and 4140.

If you are inclined to learn about 1018 vs 4140 steel, this guide below can offer some informative details. So, let's read.

What is 1018 Steel?

1018 steel has a low carbon content and is called mild steel. It also consists of less manganese and is known for its excellent hardness and strength.

It is highly machinable and can be treated under extreme temperatures. Hence, when making components of steel in various extensive applications, it proves to be an affordable choice.

Pros of 1018 Steel

• It is highly machinable, and it is very easy to weld.
• It doesn't require any pre and post-heating for welding.
• It can be formed through various cold techniques like crimping, bending, and swaging.
• It can be treated with carbo-nitriding and carburizing for case-hardening.

Cons of 1018 Steel

• It offers less ductility and yield strength.
• It lacks corrosion resistance.

What is 4140 Steel?

4140 steel is known for its seamless hardness. The presence of chromium makes it hard, and molybdenum ensures that it offers excellent strength.

Some other properties of 4140 steel are its high wear resistance, excellent ductility, and seamless toughness. It can be hardened via different techniques which include forging and heating.

Pros of 4140 Steel

• It is known for its excellent corrosion resistance.
• It offers resistance against fatigue and is known for its toughness.
• It has high yield strength and offers versatile mechanical properties.

Cons of 4140 Steel

• When welding 4140 steel, a lot of care is required.

Comparing 1018 and 4140 Steel

Chemical Composition

1018 Steel:

• Carbon: 0.0018
• Manganese: 0.6% to 0.9%
• Sulfur: 0.005
• Phosphorus: 0.004
• Iron: 98.81% to 99.26%

4140 Steel:

• Carbon: 0.004
• Manganese: 0.75% to 1%
• Sulfur: 0.0004
• Phosphorus: 0.0035
• Iron: 96.79% to 97.78%
• Molybdenum: 0.15% to 0.25%
• Chromium: 0.80% to 1.10%
• Silicon: 0.15% to 0.3%

Corrosion Resistance

1018 Steel: 1018 steel lacks corrosion resistance and cannot be used for outdoor applications.

4140 Steel: 4140 steel has chromium, which makes it highly corrosion-resistant and suitable for outdoor applications.

Yield Strength

1018 Steel: 1018 offers a yield strength of 53,700 PSI, which is not weaker and can withstand some pressure without deforming.

4140 Steel: 4140 steel has high yield strength, which is about 60,200 PSI, and therefore, it can withstand high pressure and does not deform.

Elasticity

1018 Steel: 1018 steel has 205 GPa of elasticity.

4140 Steel: The elastic modulus of 4140 steel is between 190 GPa to 210 GPa

Hardness

1018 Steel: The hardness of steel 1018 is around a rating of 130 to 140, which is sufficient to withstand deformation.

4140 Steel: 4140 steel offers a hardness rating of 200 and hence can withstand pressure without deforming.

Temperature Resistance

1018 Steel: The melting point of 1018 steel is 1420°C to 1460°C. Hence, it can withstand high temperatures.

4140 Steel: 4140 steel also has high-temperature resistance and can withstand heat treatments with melting points being 1420°C to 1460°C.

Thermal Conductivity

1018 Steel: Steel 1018 offers high thermal conductivity, which is 52 W/m-K

4140 Steel: Steel 4140 offers thermal conductivity which is less and is around 43 W/m-K

Weldability

1018 Steel: The weldability of 1018 steel is very high.

4140 Steel: 4140 steel requires heat treatments before and after welding in order to avoid cracking.

Formability

1018 Steel: 1018 steel can be formed very easily and attain all types of shapes without any heating treatments.

4140 Steel: 4140 steel requires high force and pressure for forming.

Heat Treatment

1018 Steel: Since the melting point of 1018 steel is high, it can be heat treated, but it generally does require heat treatments.

4140 Steel: 4140 steel is also capable of withstanding heat and can be heat treated using methods like hardening, hot working, annealing, cold working, forging, etc.

Mechanical Properties

Composition Costs

1018 Steel: 1018 steel is cheaper as it has a simple composition with a low content of alloys.

4140 Steel: 4140 steel is highly expensive since it has a high alloying content.

1018 Steel and 4140 Steel: Which One is Right for You?

When choosing between 1018 steel and 4140 steel you have to consider a lot of aspects regarding your applications.

You have to consider what strength is required by your application, the required corrosion resistance and heat treatments your application may need or not.

If you need components that are used outdoors, you can opt for 4140 steel because it is highly corrosion-resistant.

However, 1018 is not corrosion-resistant and is not suitable for outdoor applications.

Applications of 1018 vs 4140 Steel

1018 Steel

1018 steel is used to make components in applications that are used for low-stress environments so that they do not deform. Some of the components manufactured using 1018 steel are as follows:

• Structural parts
• Nuts
• Bolts
• Studs

4140 Steel

4140 steel is used in high-stress environments and caters to industries like machinery, automobile, and aerospace. The components manufactured using 4140 steel are as follows:

• Axles
• Crankshafts
• Gears

Conclusion

The guide above highlights in detail the comparisons of 1018 vs. 4140 steel, and you must have learned everything about it.

If you are looking forward to getting your steel components manufactured with high accuracy and are confused about which one to select, you can let us know at DEK.

FAQs

Is 1018 steel ductile or brittle?

1018 steel is ductile.

What do the digits in the steel grade indicate?

The digits in the grade consisting of the first two numbers give an indication of the type of steel and the concentration of the alloying element.

Meanwhile, the last two digits indicate the concentration of carbon.

Is 4140 a carbon steel?

Yes, it wouldn't be wrong to call 4140 carbon steel.

Is 4140 harder than 1018?

Yes, 4140 is harder and tougher compared to 1018.