DIN 1.2581

2581 steel is a hot work tool steel known for its excellent resistance to thermal fatigue. It is used primarily in applications where tools are subjected to high temperatures and cyclic heating. 

 Composition:

- Carbon (C): 0.26 - 0.35%

- Chromium (Cr): 2.50 - 3.50%

- Molybdenum (Mo): 2.00 - 2.75%

- Vanadium (V): 0.30 - 0.60%

- Tungsten (W): 8.50 - 9.50%

- Silicon (Si): 0.80 - 1.20%

Properties:

- Hardness: Typically around 52-56 HRC (Rockwell C) after heat treatment

- Density: ~7.8 g/cm³

- Tensile Strength: 1000-1300 MPa (145,000-189,000 psi)

- Yield Strength: ~800 MPa (116,000 psi)

- Elongation: ~10-15%

 Heat Treatment:

- Annealing: Heat to 820-870°C (1508-1598°F), furnace cool at a rate not exceeding 10°C (18°F) per hour.

- Hardening: Preheat at 500-600°C (932-1112°F), then raise to 970-1020°C (1778-1868°F) for 30 minutes, quench in air or oil.

- Tempering: Temper immediately after hardening. Typical tempering temperature ranges from 500-600°C (932-1112°F) for desired hardness and toughness.

 Applications:

- 2581 steel is commonly used for hot work applications such as hot forging dies, die casting tools, extrusion tools, and plastic molds.

- It is suitable for applications where tools are exposed to high temperatures during operation and require resistance to thermal fatigue and wear.

Machinability:

- 2581 steel has good machinability in the annealed condition. However, it becomes challenging to machine after heat treatment due to its high hardness.

Corrosion Resistance:

- 2581 steel has moderate resistance to corrosion but is not stainless. Proper maintenance and protection against moisture are necessary to prevent rusting.

Weldability:

- 2581 steel is not generally recommended for welding due to its high alloy content and the risk of cracking during welding. Preheating and post-weld heat treatment may be necessary if welding is unavoidable.

H21 steel's combination of high tungsten content and moderate chromium and molybdenum provides excellent resistance to thermal shock and fatigue, making it a preferred choice for hot work tooling applications. Its ability to maintain hardness and dimensional stability at elevated temperatures makes it suitable for demanding industrial environments.