S45C is among the most widely utilized steel grades for industrial bars, frequently specified by mechanical parts manufacturers and engineers for medium-load components such as shafts and gears. This guide provides a complete analysis of S45C specifications under the JIS G4051 standard, its chemical composition, and international equivalents to assist in your material selection.
Material Positioning and Standards
S45C is governed by the JIS G4051 standard for "Carbon Steels for Machine Structural Use." With a medium carbon content of approximately 0.45%, it achieves a superior balance of strength, toughness, and machinability. It is ideally suited for structural parts that require strengthening through heat treatment.
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Compared to Low Carbon Steel (e.g., S20C): S45C offers higher strength.
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Compared to High Carbon Steel (e.g., S55C): S45C is easier to machine. It is extensively used in transmission systems and general machinery applications.
Chemical Composition Specifications
According to JIS G4051, the chemical components of S45C are strictly regulated as follows:
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Carbon (C): 0.42% – 0.48%
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Silicon (Si): 0.15% – 0.35%
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Manganese (Mn): 0.60% – 0.90%
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Phosphorus (P): Maximum 0.030%
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Sulfur (S): Maximum 0.035%
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Chromium (Cr): Maximum 0.20%
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Nickel (Ni): Maximum 0.20%
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Copper (Cu): Maximum 0.30%
The low Phosphorus and Sulfur content ensures excellent toughness and fatigue life, while the Manganese level enhances the steel's hardenability.
International Equivalent Grades
S45C has high international compatibility with the following standards:
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China (GB/T 699): 45# Steel (Note: The Manganese upper limit is slightly lower at 0.50–0.80%).
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USA (AISI/SAE): 1045 (Similar composition; S45C offers slightly better hardenability due to higher Mn).
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Germany/Europe (DIN/EN): C45 (Features a narrow Silicon range of 0.10–0.40%).
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UK (BS): 080M46.
FAQ
1. Can hardness be guaranteed for hot-rolled S45C?
No, hot-rolled materials cannot guarantee a specific hardness value. A specific heat treatment process must be designated to achieve hardness requirements.
2. Is S45C easy to machine?
Yes, S45C possesses excellent machinability, making it a versatile choice for various manufacturing applications.
3. What are the results of heat treatment on S45C?
Through Quenching and Tempering (Q&T), it typically reaches HRC 30–35. With induction surface hardening, it can achieve HRC 55 or higher, depending on the environment and parameters.
Double Steel: Supply Status and Size Ranges
We maintain extensive stock with the following specifications:
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Hot-Rolled Round Bar: Ø 10mm – 250mm
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Hot-Rolled Square Steel: 9.5mm – 52.5mm
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Bright Polished Round Bar: 6mm – 100mm
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Polished Square Bar: 1/4" – 2"
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Polished Hexagonal Bar: 8mm – 65mm
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Hot-Rolled Flat Steel:
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Width (B): 12mm – 205mm
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Thickness (t): 3mm – 28mm
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Length (L): 4.5m – 13m
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