Carbon Tool Steel Equivalent Chart

Carbon Tool Steel KS Specifications — 2 sizes
KS D 3751

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.

KSCarbon Tool Steel

2 sizes
KSJISDINANSI/ASTMCategoryNote
SK3SK3C105W1W1-1.00CCarbon Tool SteelTool Steel, Drilling·
SK5SK5C85WW1-0.85CCarbon Tool SteelSpring·Cutting Tool

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.

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