What Are the Corrosion-Resistant Materials for Twin Screw Extruder Screw Elements?

In twin screw extruder operations, screw elements are not only responsible for conveying, mixing, cutting, and dispersing materials, but they also face highly corrosive processing conditions. Especially when processing plastics with chlorine, flame retardants, or highly acidic/alkaline additives, selecting the right corrosion-resistant materials becomes critical. So, what corrosion-resistant materials are available for twin screw extruder screw elements?

Key Corrosion-Resistant Materials

High-Speed Tool Steel W6Mo5Cr4V2

• Features: High hardness, excellent wear resistance
• Applications: Suitable for high-fill, high-shear conditions while maintaining durability in mildly corrosive environments

Nitrided Steel 38CrMoAl

• Features: Surface hardened through nitriding, offering improved corrosion resistance
• Applications: Ideal for general plastic processing, especially with neutral or mildly acidic materials

Powder Metallurgy (PM) Materials WR5, WR13, WR14

• Features: Combines wear resistance and corrosion resistance, suitable for high-stress corrosive environments
• Applications: High-wear and moderately corrosive composite conditions

Stainless Steel 440C / SKD11

• Features: High hardness and good corrosion resistance
• Applications: Suitable for scenarios requiring corrosion resistance while withstanding wear

Selection Recommendations

• Corrosion-focused environments: Nitrided steel, 440C, or PM WR series are recommended
• Wear + corrosion combination: WR13, WR14, or high-hardness tool steel W6Mo5Cr4V2 are more suitable
• Specialized conditions: Customized materials or surface treatments (e.g., coatings, laser cladding) can further improve corrosion performance

Summary

Choosing the right corrosion-resistant material for screw elements is key to maintaining efficient and stable twin screw extruder operation. Each material offers different advantages in wear resistance, corrosion resistance, hardness, and machinability. Proper material selection can extend screw element life, reduce maintenance costs, and improve production efficiency.

About ZHITIAN
ZHITIAN specializes in the R&D and manufacturing of twin screw extruder components, including screw elements, barrels, and gearboxes. With extensive experience in material selection, ZHITIAN can recommend the optimal material combination according to specific processing conditions.

FAQ

Q1: How to select corrosion-resistant screw element materials?
A1: Selection depends on processing conditions. For mild corrosion, nitrided steel 38CrMoAl or 440C stainless steel works well. For combined high wear and corrosion, PM-HIP materials like WR13 or WR14 are recommended. In highly specialized environments, surface treatments like laser cladding can further improve resistance.

Q2: Which materials are suitable for high-fill modified engineering plastics?
A2: High-speed tool steel W6Mo5Cr4V2 and PM-HIP materials WR5, WR13, WR14 offer excellent wear resistance while maintaining adequate corrosion resistance, making them ideal for high-fill, high-shear engineering plastics.

Q3: What is the difference between PM materials and nitrided steel?
A3: Nitrided steel has a hardened surface layer for improved corrosion resistance, but the core hardness is lower. PM (powder metallurgy) materials are sintered to have uniform hardness and microstructure, providing superior wear and corrosion performance for heavy-duty applications.

Q4: Can these materials be customized for specific extruder applications?
A4: Yes. ZHITIAN offers customized screw elements based on material, geometry, and surface treatment requirements to meet specific production and industry needs.

Q5: How does corrosion-resistant material affect screw element life?
A5: Using appropriate corrosion-resistant materials significantly extends the operational life of screw elements, reduces downtime for maintenance, and improves overall production efficiency.