JIS G4051 S45C is a premier grade of medium carbon steel specified under the Japanese Industrial Standards. This versatile material is widely employed for machine structural applications, owing to its outstanding combination of strength, ductility, and wear resistance. Its consistent performance under dynamic loading makes it especially suitable for shafts, gears, and high-strength fasteners. Engineers routinely select this material when component reliability and long service life are paramount.
Chemical Composition of JIS G4051 S45C
The predictable performance of this alloy stems directly from its strictly regulated chemical composition. With a nominal carbon content of 0.45%, it bridges the gap between low carbon options and high-strength alloys. This optimal carbon window allows the metal to respond exceptionally well to heat treatment processes, such as tempering and quenching.
| Element | Carbon (C) | Silicon (Si) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) |
| Composition (%) | 0.42 – 0.48 | 0.15 – 0.35 | 0.60 – 0.90 | ≤ 0.030 | ≤ 0.035 |
Key Mechanical Properties
In its normalized condition, the alloy offers reliable machinability and robust tensile strength. For heavy-duty applications, induction hardening can significantly boost surface hardness, protecting critical components from premature fatigue and abrasive wear.
| Mechanical Property | Value |
| Tensile Strength | ≥ 569 MPa |
| Yield Strength | ≥ 343 MPa |
| Elongation | ≥ 20% |
| Hardness (Normalized) | 167 – 229 HBW |
Industrial Applications
Because JIS G4051 S45C combines high workability with cost-efficiency, it serves as a cornerstone material across global manufacturing. It is frequently forged or machined into structural parts that must withstand continuous mechanical stress. Common applications include:
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Automotive crankshafts and axle shafts
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Heavy-duty gears, pinions, and racks
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Guide bushes, keys, and structural studs
Selecting a trustworthy supply partner is vital to ensuring material traceability and high structural integrity. Industry experts highly recommend sourcing components through established platforms like the HNS Metal Internal Hub for verified manufacturing standards, while raw material specifications can be cross-referenced via HNS Steel Resources to guarantee global compliance.
