STAVAX (AISI 420 Modified) Detailed Information
STAVAX is a premium-grade stainless tool steel developed by Böhler-Uddeholm, widely recognized for its exceptional corrosion resistance, polishability, and wear resistance. It is a modified version of AISI 420 tool steel, designed specifically for plastic injection molds and other applications requiring a high-gloss surface finish.
This material is commonly used in medical, optical, and high-precision plastic molding applications, where corrosion resistance and high surface quality are essential. STAVAX ensures long mold life, reducing the need for frequent maintenance and increasing productivity.
Key Features
Excellent Corrosion Resistance
- Resistant to moisture, acidic gases, and corrosive plastics (e.g., PVC).
- Ideal for molds used in high-humidity or aggressive processing conditions.
Superior Polishability
- Achieves a mirror-like finish, making it ideal for optical lenses, medical devices, and aesthetic plastic components.
Good Wear Resistance
- Suitable for high-cycle injection molding, even with abrasive plastic materials.
High Hardness Retention
- Remains dimensionally stable under repeated high-pressure molding conditions.
Low Maintenance & Longer Mold Life
- Reduces mold wear and corrosion-related failures, minimizing downtime and repair costs.
Chemical Composition
| Element | Composition (%) |
| Carbon (C) | 0.38–0.42 |
| Silicon (Si) | 0.90–1.20 |
| Manganese (Mn) | 0.50–0.90 |
| Chromium (Cr) | 13.50–14.50 |
| Molybdenum (Mo) | 0.20–0.60 |
| Nickel (Ni) | ~0.30 |
| Phosphorus (P) | ≤0.025 |
| Sulfur (S) | ≤0.003 |
- High Chromium Content (13.5–14.5%) → Provides excellent corrosion resistance.
- Low Sulfur Content → Ensures exceptional polishability.
- Moderate Carbon Content (0.38–0.42%) → Balances hardness and toughness.
Mechanical Properties
| Property | Value |
| Hardness (Annealed) | ~200 HB |
| Hardness (After Heat Treatment) | 48–52 HRC |
| Tensile Strength | ~1,350 MPa |
| Yield Strength | ~1,200 MPa |
| Impact Toughness | High |
| Wear Resistance | Good |
| Corrosion Resistance | Excellent |
| Polishability | Outstanding |
- High Hardness (48-52 HRC) → Suitable for high-pressure injection molding.
- Outstanding Polishability → Ideal for transparent and optical-grade plastic molding.
- Excellent Corrosion Resistance → Reduces mold maintenance in humid or corrosive environments.
STAVAX vs. Other Stainless Tool Steels
| Property | STAVAX | S136H | 1.2083 | 420SS |
| Hardness (After Heat Treatment) | 48-52 HRC | 48-52 HRC | 52-56 HRC | 40-45 HRC |
| Corrosion Resistance | Excellent | Excellent | Moderate | Good |
| Wear Resistance | Good | Good | Excellent | Moderate |
| Polishability | Outstanding | Excellent | Moderate | Good |
| Toughness | High | Moderate | High | Moderate |
| Applications | Optical & Medical Molds | Plastic Injection Molds | High-Wear Molds | General Mold Use |
Why Choose STAVAX?
- Better polishability than S136H.
- Superior corrosion resistance compared to 420SS.
- Lower wear resistance than 1.2083, but higher toughness.
Applications
Plastic Injection Molds
- High-gloss plastic parts (e.g., mobile phone covers, cosmetic packaging).
- Optical components (e.g., camera lenses, LED diffusers).
- Medical plastic parts (e.g., syringes, test tubes).
Blow Molding Dies
- Hollow plastic products requiring a high-polish surface.
Rubber & Composite Molds
- Used for high-precision medical and industrial applications.
Food & Pharmaceutical Molding
Suitable for food-safe molds due to its corrosion resistance.
Heat Treatment Process
Soft Annealing
- Heat to 850–900°C, then slowly cool to 600°C.
- Improves machinability before hardening.
Hardening
- Preheat at 800–900°C, then increase to 1,020–1,050°C.
- Oil, vacuum, or air quenching is recommended.
Tempering
- 200–300°C, repeated twice to achieve final hardness (48–52 HRC).
Nitriding (Optional for Surface Hardness Enhancement)
- Improves wear resistance while maintaining corrosion resistance.
Alternative Materials
- S136H: Similar properties but slightly less polishable than STAVAX.
- 1.2083: Higher wear resistance, but lower corrosion resistance.
- HPM38: Another high-purity stainless steel with enhanced toughness.
Conclusion
STAVAX is a premium stainless tool steel designed for high-precision plastic molding that requires excellent corrosion resistance, polishability, and wear resistance. It is widely used in optical, medical, and high-gloss plastic molding applications, ensuring long mold life and minimal maintenance.
Best Choice for: High-gloss plastic molds, medical device manufacturing, and corrosion-resistant mold applications.
Why Choose STAVAX? Outstanding polishability, high corrosion resistance, and excellent dimensional stability in plastic molding.
