SteelWhat is S7 steel and what is it used for? Shock-resistant tool steel
S7 steel is a shock-resistant tool steel. In this guide we explain what S7 steel is, its chemical composition, hardness, how it is heat treated, what it is used for and the sizes we stock.
What is S7 steel?
Chrome-molybdenum tool steel, air or oil hardening, with very high impact and shock resistance. For tools and dies subject to dynamic loads and impact.
Chemical composition of S7 steel
This is the typical composition of S7 steel (AISI S7 / ASTM A681 / EN-DIN 1.2355 standard):
| Element | Contents | What for? |
|---|---|---|
| Carbon (C) | 0.45 – 0.55 % | Hardness and wear resistance |
| Silicon (Si) | 0.20 – 1.00 % | Deoxidizer |
| Manganese (Mn) | 0.20 – 0.90 % | Hardenability |
| Chromium (Cr) | 3.00 – 3.50 % | Hardenability and wear resistance |
| Molybdenum (Mo) | 1.30 – 1.80 % | Hot hardness and hardenability |
| Vanadium (V) | 0.35 % max. | Refines the grain and forms hard carbides |
| Phosphorus (P) | 0.030 % max. | Impurity, kept low |
| Sulfur (S) | 0.030 % max. | Impurity, kept low |
Hardness and heat treatment of S7 steel
The typical working hardness of S7 is 54 – 58 HRC. It is air- or oil-quenched and tempered. It is formulated to absorb shock and dynamic loads without chipping, prioritizing toughness over extreme hardness. You can see the full overview in our article on heat treatments for steel, and hardness scales in steel hardness.
What is it for? Applications of S7
S7 steel is mainly used in:
- Impact punches
- Industrial chisels
- Shear blades
- Forging dies
- Stamping dies
- Ejector pins
- Industrial mandrels
- Pneumatic tools
- Heading dies
Forms and sizes we carry
At NAT MAC we stock S7 steel in these forms and sizes:
| Package size | Sizes |
|---|---|
| Round bars | Ø 1/2" – 4" (Ø 13 – 102 mm) |
| Plates | 1/4" – 12" (6 – 305 mm) |
If you need a particular size, tell us which one and we will gladly source it for you.
S7 equivalents and standards
S7 steel is also identified by these standards: AISI S7 / ASTM A681 / EN-DIN 1.2355. You can see how to read them in our article on steel standards.
In summary
- S7 is a shock-resistant tool steel
- Typical composition: C 0.45 – 0.55 and Cr 3.00 – 3.50, plus alloying elements
- Typical working hardness: 54 – 58 HRC
- Ideal for maximum impact and shock resistance
- We carry it in round bar (1/2" – 4") and plates (1/4" – 12"), cut to size
Why buy your S7 steel at NAT MAC?
We have more than 54 years of experience as an industrial supplier and ISO 9001 certified quality. We carry a wide range of tool grade steels and help you choose the right one for your tool or mold.
- Quality S7 Steel, backed and traceable
- Material cut to the size you need
- Technical advice on choosing the right grade
- Wide range of tool-grade steels in stock
- On-time deliveries and competitive prices
Tell us what tool or mold you are going to make and in what dimensions, and we will recommend the right grade and form. Request your free quote.
Sources: data sheet from our NAT MAC catalog (composition, sizes and applications) and public industry references for working hardness. Values are for reference and may vary by standard, heat and treatment.
