Grade S1/ 1.2550 (60WCrV8), is a shock-resisting tool steel developed specifically for applications where tools must withstand heavy impact, repeated shock loading, and rough working conditions. It is part of the S-series of ASTM shock-resisting steels, designed to deliver high toughness, good ductility, and excellent resistance to chipping or cracking.

S1 is a tungsten-bearing steel that offers a powerful combination of impact strength, hardness, and deep hardenability, making it an excellent choice for forging and striking tools.

Key Properties of S1/ 1.2550

1. Exceptional Shock Resistance

The primary strength of S1 is its ability to handle strong impacts, vibrations, and sudden loads without cracking.
Ideal for tools repeatedly struck with force.

2. Good Toughness & Wear Resistance

S1 offers a perfect balance between toughness and medium wear resistance, making it suitable for both impact and light cutting operations.

3. High Hardness After Heat Treatment

When hardened, S1 typically reaches 54–58 HRC, depending on quenching medium.
Despite this hardness, it retains ductility and resistance to chipping.

4. Thermal Shock Resistance

S1 performs well under rapid temperature changes, making it ideal for forging tools exposed to hot metal and cooling cycles.

5. Deep Hardenability

Thanks to tungsten and chromium, S1 hardens uniformly even in larger sections, reducing the risk of soft spots in heavy tools.

6. Good Machinability in Annealed Condition

S1 is easy to machine, drill, and mill before hardening, reducing production time and tooling costs.

Common Applications

S1/ 1.2550 is widely used for tools subjected to heavy impact, repeated blows, and rapid temperature variations, including:

1. Hot & cold chisels

2. Hammers and sledgehammer tools

3. Punches and drift tools

4. Hot forging dies

5. Riveting and boiler tools

6. Cold headers and upsetter tools

7. Heavy-duty woodworking tools

8. Shear blades for shock applications

9. Picks, axes, and impact knives

Summary

Grade S1/ 1.2550 is a highly reliable shock-resisting tool steel offering outstanding impact strength, stability, and durability. It is the best choice for tools used in harsh conditions where resistance to cracking, impact, and thermal shock is critical. Its toughness, hardenability, and ease of machining make it a preferred grade for forging tools, chisels, punches, and striking implements.