S7 is a shock-resisting tool steel made to take heavy impact without chipping or cracking. It hardens to about 54–58 HRC, lower than D2, but with much higher toughness. It is used for chisels, punches for thick plate, rivet sets, shear blades, hammer tools and plastic mould parts that see impact.
Quick facts
- Type
- Shock-resisting tool steel
- Carbon
- About 0.45–0.55%
- Main alloys
- Chromium about 3.25%, molybdenum about 1.4%
- Hardness
- About 54–58 HRC
- Hardening
- Air or oil from about 930–955 °C
- Toughness
- Very high
Equivalent grades
| Standard | Grade |
|---|---|
| AISI | S7 |
| DIN | 1.2357 (close) |
Equivalents are close, not identical. Name the grade and standard on the drawing.
Typical chemical composition
| Element | % |
|---|---|
| Carbon (C) | About 0.45–0.55 |
| Chromium (Cr) | About 3.0–3.5 |
| Molybdenum (Mo) | About 1.3–1.8 |
| Silicon (Si) | About 0.2–1.0 |
Values are typical. The exact limits depend on the standard and supplier; ask for the mill test certificate when it matters.
Typical uses
- Chisels and punches for thick plate
- Rivet sets and riveting tools
- Heavy shear blades
- Hammer and impact tools
- Mould parts under impact
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Questions
- When to choose S7 over D2?
- When tools see heavy impact and D2 would chip or crack, even if S7 wears faster.
- How hard does S7 get?
- About 54–58 HRC, chosen with the tempering temperature.
- Is S7 good for moulds?
- Yes, for mould parts that take knocks, though P20 or H13 are more common for plastic moulds.
The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 23 October 2026.