45# carbon steel (also known as 45# steel or S45C in JIS standard) is a high-quality medium-carbon structural steel defined by Chinese standard GB/T 699. With a carbon content of around 0.45%, it offers high strength, good machinability, and excellent wear resistance after quenching and tempering. 45# steel is widely used for manufacturing mechanical parts such as shafts, gears, and connecting rods that require high strength and toughness. It is equivalent to AISI 1045 (USA) and EN C45 (Europe).
Chemical Composition
Typical chemical composition (% by mass) per GB/T 699.
| Grade | C (%) | Si (%) | Mn (%) | P (%) | S (%) |
|---|---|---|---|---|---|
| 45# | 0.42–0.50 | 0.17–0.37 | 0.50–0.80 | ≤0.035 | ≤0.035 |
Note: 45# steel has higher carbon content than 20#, providing better strength and hardness but reduced weldability. It is typically used after normalizing or quenching and tempering.
Mechanical Properties
| Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Hardness (HB) |
|---|---|---|---|---|
| 45# (Normalized) | ≥355 | ≥600 | ≥16 | ≤197 (Annealed) |
Available Sizes & Delivery
| Thickness (Plate/Sheet) | 0.5–200 mm |
| Diameter (Round Bar) | 10–500 mm |
| Forms Available | Plate, round bar, flat bar, square bar, forging |
| Standard | GB/T 699 / GB/T 711 |
| Mill Test Certificate | EN 10204 3.1 with every shipment |
| MOQ | 3 Tons |
| Delivery Time | Within 7 days (≤500 tons) |
Why Order from Zhongtang Steel?
- High Strength & Wear Resistance — excellent mechanical properties after heat treatment
- EN 10204 3.1 MTC supplied with every shipment
- ISO 9001 certified manufacturer since 1998
- Mill-direct pricing — no trading company markup
- Global shipping — FOB, CFR, CIF available
Applications
- Mechanical parts such as shafts, gears, and connecting rods
- High-strength bolts, nuts, and fasteners
- Automotive and agricultural machinery components
- Molds and tooling bases requiring high hardness
- Hydraulic cylinders and piston rods
- General engineering structural components
Values are typical reference ranges per GB/T 699. Actual properties may vary by mill and production route. Mill test certificates (EN 10204 3.1) are supplied with every shipment — contact us for exact data sheets.
