SKD61 Steel Technical Overview

SKD61 Tool Steel Technical Overview: SKD61 is a versatile hot work die steel defined by the Japanese Industrial Standard (JIS G4404). It’s crucial for engineers and buyers working with international projects or diverse supply chains to recognize its equivalent grades across different standards.

1. Chemical Composition (JIS G4404-2006, Weight %)

• Carbon (C):32 – 0.42%
• Silicon (Si):≤ 1.00%
• Manganese (Mn):≤ 0.50%
• Chromium (Cr):50 – 5.50% (Key for hardenability and wear resistance)
• Molybdenum (Mo):20 – 1.60% (Enhances high-temperature strength and resistance to softening)
• Vanadium (V):80 – 1.20% (Promotes fine grain structure, improving toughness and wear resistance)

(Note: Exact composition ranges may vary slightly based on the specific standard or supplier specifications.)

2. SKD61 Equivalent Grades

Knowing these equivalents simplifies material specification, sourcing, and cross-referencing:

• American ASTM: H13
• International ISO: 35CrMoV5
• German DIN: 1.2344/X40CrMoV5-1

3. Key Characteristics of SKD61 Steel

SKD61 steel delivers reliable performance in demanding high-temperature, high-stress environments due to its core properties:

• Good Hardenability: Achieves consistent hardness through the cross-section, even in larger tools, which is vital for performance and tool longevity.
• High Wear Resistance: Effectively withstands abrasive conditions in many industrial forming and tooling processes.
• Resistance to Thermal Fatigue and Hot Cracking: Crucial for tooling subjected to repeated cycles of heating and cooling under significant stress.
• Resistance to Softening at Elevated Temperatures: Maintains its hardness and structural integrity during demanding hot work operations.
• Good Toughness: Results from a microstructure featuring fine, uniformly distributed carbides.

Important Processing Note: SKD61 requires careful control during heat treatment processes to avoid potential issues like decarburization or overheating.

4. SKD61 Tool Steel Heat Treatment

Precise heat treatment is essential to unlock the full potential of SKD61 Tool Steel. Common parameters are:

4.1 Hot Working / Forging: The Optimal temperature range typically starts around 1100°C and finishes near 900°C.

4.2 Hardening:

• Preheating: Generally around 790°C.
• Austenitizing: Heat to 1000°C (salt bath) or 1010°C (controlled atmosphere furnace), holding for 5-15 minutes.
• Quenching: Air cooling is usually sufficient due to SKD61’s good hardenability.

4.3 Tempering: Tempering around 550°C is often employed to achieve the target balance of hardness (e.g., ≥60 HRC) and toughness.

Adhering strictly to recommended heat treatment protocols is critical for maximizing the service life and performance of components made from SKD61.

5. Applications for SKD61

The combination of strength, toughness, wear resistance, and high-temperature performance makes SKD61 a reliable material for various demanding tooling applications:

• Dies for hot extrusion of aluminum and other non-ferrous metals
• Die casting dies, particularly for aluminum alloys (due to resistance to thermal fatigue and erosion from molten metal)
• Forging dies
• Bolt heading dies
• Hot shearing blades
• Mandrels
• Punches