6Cr4Mo3Ni2WV (CG2) Hot Work Tool Steel Properties

6Cr4Mo3Ni2WV Tool Steel, also known by the designation CG2, is a high-strength matrix steel developed for demanding applications. It serves as a versatile die steel suitable for both cold working and hot working processes.

1.  6Cr4Mo3Ni2WV Tool Steel Chemical Composition

The performance of 6Cr4Mo3Ni2WV steel relies on its specific alloy composition. While slight variations exist between different standards or sources, a typical composition range (mass fraction, %) is:

• Carbon (C): 0.55 – 0.64%
• Silicon (Si): ≤0.40%
• Manganese (Mn): ≤0.40%
• Phosphorus (P): ≤0.030%
• Sulfur (S): ≤0.030%
• Chromium (Cr): 3.80 – 4.30% 
• Molybdenum (Mo): 2.80 – 3.30% 
• Nickel (Ni): 1.80 – 2.20% 
• Tungsten (W): 0.90 – 1.30% 
• Vanadium (V): 0.90 – 1.30%

Key alloying elements contribute specific benefits:

• Nickel (Ni): Added to strengthen the steel matrix, improving toughness and performance at high temperatures.
• Molybdenum (Mo): Partially substitutes for Tungsten (W) to help reduce carbide segregation.

It is important to confirm the exact specification required for your application.

2. 6Cr4Mo3Ni2WV Tool Steel Properties and Characteristics

6Cr4Mo3Ni2WV (CG2) steel provides a suitable balance of strength and fracture toughness.

• High Strength: Suitable for tools and dies operating under heavy loads.
• Good Toughness: Provides resistance to fracture.
• Versatility: Can be used as a replacement for 3Cr2W8V tool steel in certain forging die applications, often providing economic advantages.
• Surface Treatment: Performance can be further enhanced through surface treatments, such as carbonitriding (also known as soft nitriding), which increases wear resistance and extends die life.

Mechanical property data (example values, specific heat treatment conditions may vary):

• Tensile Strength (Rm): ~1530 MPa
• Yield Strength (Rp0.2): ~820 MPa
• Fracture Toughness (KIC, Room Temp): ~18.0 MPa√m
• Hardness (Post Quench & Temper): Can vary significantly based on tempering temperature (e.g., ranges observed from ~119 HBW to ~391 HBW).

3. 6Cr4Mo3Ni2WV Tool Steel Heat Treatment

Proper heat treatment is critical to achieve the desired properties for 6Cr4Mo3Ni2WV.

• Annealing: Heat to 860°C, then cool the furnace to 740°C and hold. Continue furnace cooling to ≤400°C, followed by air cooling.
• Hardening: Preheat (e.g., 800°C), heat to austenitizing temperature (e.g., 1120°C in a salt bath), quench (typically in oil), followed by tempering (e.g., 420°C, 1 hour; double tempering is recommended).

Crucially, precise temperature control during heat treatment is essential. Overheating can lead to undesirable microstructures, such as aligned martensite and grain growth, which negatively impact performance.

4. 6Cr4Mo3Ni2WV Tool Steel Applications

The properties of 6Cr4Mo3Ni2WV Tool Steel make it suitable for a range of demanding tool and die applications:

• Hot Working:
  
  • Hot forging dies
  • Punches for screws and hot rivets
  • Die cores for high-temperature die-casting (light alloys)
  • Hot extrusion molds
• Cold Working:
  
  • Cold working dies
  • Molds and dies under heavy load
  • Pneumatic chisels

Its balance of strength and toughness makes it a good choice where resistance to both wear and fracture is required.

5. Important Considerations

While a capable steel, a successful implementation requires attention to:

• Machinability: The annealed hardness can be relatively high, which may require adjustments in machining processes.
• Hot Processing: The steel can be susceptible to internal cracking during hot working if parameters are not carefully controlled. This is a factor to manage during the forging or manufacturing process.
• Application Suitability: Although sometimes used as an alternative to 3Cr2W8V tool steel, it may share similar vulnerabilities, such as cracking, under specific high-stress conditions. Careful analysis of the intended application’s loads, temperatures, and wear mechanisms is necessary.

At Aobo Steel, we have extensive experience with tool steels, such as 6Cr4Mo3Ni2WV steel. Contact us to discuss your specific requirements and ensure you select the optimal material for your application.