SteelWhat is 1018 steel and what is it used for? Low-carbon steel
1018 steel is one of the most widely used low-carbon steels: economical and easy to machine, weld and form. In this guide we explain what 1018 steel is, its composition, its properties, what it is used for and the sizes we stock.
What is 1018 steel?
Low-carbon steel (SAE 1018), sold mainly as round, square, and hex bars and flat bars. It offers good machinability, excellent weldability, and easy forming; it is supplied mostly cold drawn (calibrated). For shafts, pins, bolts, bushings, keys, and machined components; suitable for carburizing.
Chemical composition of 1018 steel
This is the typical composition of 1018 steel (AISI 1018 standard):
| Element | Contents | What for? |
|---|---|---|
| Carbon (C) | 0.15 – 0.20 % | Provides hardness and strength |
| Manganese (Mn) | 0.60 – 0.90 % | Hardenability and strength |
| Phosphorus (P) | 0.040 % max. | Impurity, kept low |
| Sulfur (S) | 0.050 % max. | Impurity, kept low |
1018 properties and treatment
1018 is a low-carbon steel with very good machinability, weldability and ease of forming. Cold drawn (sized) its hardness is around 160 to 180 HB. Because of its low carbon it does not harden by direct quenching, but it is suitable for carburizing (carburizing): carbon is added at the surface to harden it and leave the core tough. You can see the overview in our article on heat treatments for steel.
What is it for? Applications of 1018
1018 steel is mainly used in:
- Axles and shafts
- Bolts and screws
- Bushings and sleeves
- Low-load gears
- Pinions and sprockets
- Automotive components
- CNC machined parts
- Supports and couplings
- Case-hardened and carburized parts
Forms and sizes we carry
At NAT MAC we stock 1018 steel in these forms and sizes:
| Package size | Sizes |
|---|---|
| Round bars | Ø 1/8" – 6 1/2" (3.2 – 165.1 mm) |
| Square bars | 1/8" – 4" (3.2 – 101.6 mm) |
| Hex bars | 3/8" – 2" (9.5 – 50.8 mm) |
| Flat bars | 1/8"×1/2" a 3"×8" |
If you need a particular size, tell us which one and we will gladly source it for you.
1018 equivalents and standards
1018 steel is also identified by these standards: AISI 1018 You can see how to read them in our article on steel standards.
Theoretical weight of 1018 steel
To estimate freight, handling or costs, this is the reference theoretical weight per size, calculated with a density of 7.85 g/cm³ (the same one our calculator uses). Actual weight may vary due to manufacturing tolerances.
| Round bar Ø | mm | kg per meter |
|---|---|---|
| 1/4" | 6.3 | 0.25 |
| 1/2" | 12.7 | 0.99 |
| 3/4" | 19 | 2.24 |
| 1" | 25.4 | 3.98 |
| 1 1/2" | 38.1 | 8.95 |
| 2" | 50.8 | 15.9 |
| 3" | 76.2 | 35.8 |
| 4" | 101.6 | 63.6 |
| 6" | 152.4 | 143 |
| Square bar | mm | kg per meter |
|---|---|---|
| 1/2" | 12.7 | 1.27 |
| 3/4" | 19 | 2.85 |
| 1" | 25.4 | 5.06 |
| 1 1/2" | 38.1 | 11.4 |
| 2" | 50.8 | 20.3 |
| 3" | 76.2 | 45.6 |
| 4" | 101.6 | 81.0 |
| Hex bar (across flats) | mm | kg per meter |
|---|---|---|
| 1/2" | 12.7 | 1.10 |
| 3/4" | 19 | 2.47 |
| 1" | 25.4 | 4.39 |
| 1 1/2" | 38.1 | 9.87 |
| 2" | 50.8 | 17.5 |
Need another size? Get the exact weight with the Steel weight calculator: choose the grade, form and dimensions and get the result instantly.
In summary
- 1018 is a low-carbon steel that is easy to machine, weld and form
- Typical composition: C 0.15–0.20 %, Mn 0.60–0.90 %
- Cold drawn ~160–180 HB; does not harden directly, but is suitable for carburizing
- Ideal for shafts, axles, bolts, bushings and machined parts
- We carry it in round bars, square bars, hex bars, flat bars, cut to size
Frequently asked questions about 1018 steel
Can 1018 steel be hardened?
Because of its low carbon content it does not harden by direct quenching, but it is suitable for case hardening (carburizing): carbon is added to the surface to harden it while the core stays tough.
What is the hardness of 1018 steel?
Cold drawn, its hardness is around 160 to 180 HB.
What is the difference between 1018 and 1045 steel?
1018 is a low carbon steel (0.15 to 0.20 %): it machines, welds and forms easily. 1045 is a medium carbon steel (0.43 to 0.50 %): it is stronger and can be quenched and tempered, but its weldability is limited.
How much does a 1018 steel bar weigh?
With a density of 7.85 g/cm³, a 1" round bar weighs about 3.98 kg per meter and a 1" square bar about 5.06 kg per meter.
What forms of 1018 steel do you carry?
Round bar from 1/8" to 6 1/2", square bar from 1/8" to 4", hex bar from 3/8" to 2" and flat bar from 1/8"×1/2" to 3"×8".
Why buy 1018 steel at NAT MAC?
We have more than 54 years of experience as an industrial supplier and ISO 9001 certified quality. We carry a wide range of carbon steels and help you choose the right one for your part.
- Quality 1018 Steel, backed and traceable
- Material cut to the size you need
- Technical advice on choosing the right grade
- Wide range of carbon steels in stock
- On-time deliveries and competitive prices
Tell us what you are going to make and in what dimensions, and we will recommend the right material and form. Request your free quote.
Sources: data sheet from our NAT MAC catalog (composition, sizes and applications) and public industry references for hardness. Values are for reference and may vary by standard, heat and treatment.
