SteelWhat is 1045 steel and what is it used for? Medium-carbon steel
1045 steel is the most common medium-carbon steel: when you need more strength and hardness than a low-carbon steel, it is the benchmark. In this guide we explain what 1045 steel is, its composition, its properties, what it is used for and the sizes we stock.
What is 1045 steel?
Medium-carbon steel (SAE/AISI 1045) with a good combination of mechanical strength, hardness, toughness, and machinability; compared with low-carbon steels, it withstands higher loads, moderate impact, and wear conditions. It can be supplied hot forged, hot rolled, cold drawn, normalized, annealed, or heat treated. It accepts quenching and tempering, as well as induction or flame surface hardening. It is used in shafts, gears, bolts, keys, rollers, screws, and machined components subject to mechanical stress; because of its medium carbon content, it has limited weldability.
Chemical composition of 1045 steel
This is the typical composition of 1045 steel (AISI 1045 / EN C45 / DIN Ck45 / JIS S45C standard):
| Element | Contents | What for? |
|---|---|---|
| Carbon (C) | 0.43 – 0.50 % | Provides hardness and strength |
| Silicon (Si) | 0.15 – 0.35 % | Deoxidizer, adds 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 |
Hardness and heat treatment of 1045 steel
1045 is a medium-carbon steel, so unlike 1018 it does accepts quenching and tempering: with heat treatment it reaches high hardness (on the order of 45 to 55 HRC depending on the tempering) and it can also be surface-hardened by induction or flame. Rolled or drawn, it is around 170 to 200 HB. In exchange for that greater strength, its weldability is limited by carbon content. We explain the hardness scales in steel hardness.
What is it for? Applications of 1045
1045 steel is mainly used in:
- Axles and shafts
- Gears and pinions
- High-strength bolts
- Studs and bolts
- Industrial rollers
- Crankshafts and connecting rods
- Mechanical couplings
- Wedges and keys
- Machinery components
Forms and sizes we carry
At NAT MAC we stock 1045 steel in these forms and sizes:
| Package size | Sizes |
|---|---|
| Plates | 1/2" – 10" (12.7 – 254 mm) |
| Round bars | 1/4" – 4" (6.3 – 101.6 mm) |
| Flat bars | Made to length |
If you need a particular size, tell us which one and we will gladly source it for you.
1045 equivalents and standards
1045 steel is also identified by these standards: AISI 1045 / EN C45 / DIN Ck45 / JIS S45C You can see how to read them in our article on steel standards.
Theoretical weight of 1045 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 |
| Plate (thickness) | mm | kg per m² |
|---|---|---|
| 1/2" | 12.7 | 99.7 |
| 3/4" | 19 | 150 |
| 1" | 25.4 | 199 |
| 2" | 50.8 | 399 |
| 3" | 76.2 | 598 |
| 4" | 101.6 | 798 |
| 6" | 152.4 | 1,196 |
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
- 1045 is a medium-carbon steel with good strength, hardness and toughness
- Typical composition: C 0.43–0.50 %, Mn 0.60–0.90 %
- Accepts quenching and tempering (45–55 HRC) and induction hardening; limited weldability
- Ideal for shafts, gears, crankshafts, bolts and machinery components
- We carry it in plates, round bars, flat bars, cut to size
Frequently asked questions about 1045 steel
What is the hardness of 1045 steel?
Hot rolled or cold drawn it is around 170 to 200 HB. Quenched and tempered it reaches roughly 45 to 55 HRC depending on the tempering, and the surface alone can also be hardened by induction or flame.
What is the equivalent of 1045 steel?
It is C45 in the European standard, Ck45 in DIN and S45C in JIS.
Can 1045 steel be welded?
Its weldability is limited by its medium carbon content; if it will be welded, a procedure with preheating is recommended.
What is the difference between 1045 and 4140 steel?
1045 is a carbon steel for shafts, gears and medium-stress parts. 4140 is a chromium-molybdenum steel, delivered quenched and tempered (28 to 34 HRC) with higher hardenability, so it suits parts with higher torsion and fatigue demands.
How much does a 1045 steel bar weigh?
With a density of 7.85 g/cm³, a 1" round bar weighs about 3.98 kg per meter and a 2" bar about 15.9 kg per meter.
Why buy 1045 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 1045 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.
