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Carbon Tool Steel Spec Table
Carbon Tool Steel KS Specifications — 2 sizes
KS D 3751
KSCarbon Tool Steel
2 sizes| Name | Type | Tensile | Yield | Hardness | Use |
|---|---|---|---|---|---|
| SK3(SK105) | Carbon Tool Steel | - | - | HRC60~65(Heat TreatedAfter) | , , Drilling, , Cutting Tool |
| SK5(SK85) | Carbon Tool Steel | - | - | HRC58~63(Heat TreatedAfter) | Spring, , Blade, |
SK3 (KS/JIS) = C80W2 (DIN) = W1 (ANSI): equivalent carbon tool steels. The base material for small tools such as drills, punches, and taps.
Practical Notes
- SK3 achieves HRC 60+ hardness after heat treatment but low toughness makes it impact-sensitive. Use alloy tool steel (SKD) for impact-prone applications.
- Hardness drops sharply above 200°C (temper softening). Use high-speed steel (SKH) for hot cutting applications.
Key Features
- STC (SK) series; C 0.6–1.5% achieves HRC 60–67 high hardness after quenching
- Low cost makes it economical for simple-shaped tools and gauges
- Hardness drops sharply above 200 °C (temper softening); unsuitable for high-speed cutting/hot dies
Key Applications
Hand tools (files, chisels, punches), springs, gauges, woodworking tools, mold ejector pins
FAQ
Difference between SK3, SK5, and SK7?
Carbon content difference. SK3 (C=1.0–1.1%)→highest hardness, SK5 (C=0.80–0.90%)→general purpose, SK7 (C=0.60–0.70%)→toughness focus. Lower numbers = higher hardness.