Duplex Stainless Steel

Duplex 2205 Stainless Steel CNC Machining

Name: Duplex 2205 Stainless Steel CNC Machining Services
Brand: Fedele Autocore
Availability: InStock

Superior corrosion resistance and twice the strength of austenitic stainless steels. The optimal choice for marine, oil & gas, and chemical processing applications in Australia.

View Properties

Material Specifications

Designation: UNS S32205 / EN 1.4462

Type: Duplex (Ferritic-Austenitic)

Density: 7.8 g/cm³

Melting Point: 1350-1400°C

Australian Standard: AS 2837 Grade 2205

Why Choose Duplex 2205?

Duplex 2205 combines the best characteristics of austenitic and ferritic stainless steels, delivering exceptional performance in the most demanding environments.

Superior Corrosion Resistance

Exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking. PREN 35+ for marine and chloride environments.

High Strength

Yield strength twice that of 316L (450+ MPa vs 220 MPa). Enables thinner wall sections and lighter designs without compromising integrity.

Cost Effective

Lower nickel content than austenitic grades reduces material costs. Higher strength allows material savings through design optimization.

Excellent Weldability

Good weldability without preheating. Balanced microstructure maintains corrosion resistance in welded joints and heat-affected zones.

Technical Properties & Composition

Chemical Composition (Weight %)

Element	Composition %	Purpose
Carbon (C)	≤ 0.030	Minimized to prevent carbide precipitation
Chromium (Cr)	21.0 - 23.0	Primary corrosion resistance and passivation
Nickel (Ni)	4.5 - 6.5	Austenite stabilizer, toughness improvement
Molybdenum (Mo)	2.5 - 3.5	Enhanced pitting and crevice corrosion resistance
Nitrogen (N)	0.14 - 0.20	Strength, austenite stabilization, corrosion resistance
Manganese (Mn)	≤ 2.0	Deoxidizer, nitrogen solubility
Silicon (Si)	≤ 1.0	Deoxidizer, improved oxidation resistance
Phosphorus (P)	≤ 0.030	Controlled as impurity
Sulfur (S)	≤ 0.020	Controlled as impurity affecting corrosion

PREN Value: Pitting Resistance Equivalent Number (PREN) = %Cr + 3.3×%Mo + 16×%N = 35-38 (Superior to 316L at 24-26)

Mechanical Properties at 20°C

Property	Value
Tensile Strength (Rm)	640-840 MPa
Yield Strength (Rp0.2)	450-550 MPa
Elongation (A5)	≥ 25%
Hardness	≤ 290 HB
Impact Energy (-40°C)	≥ 60 J

Physical Property	Value
Density	7.8 g/cm³
Elastic Modulus	200 GPa
Thermal Conductivity (20°C)	15 W/m·K
Thermal Expansion (20-100°C)	13.0 × 10⁻⁶ /°C
Electrical Resistivity	0.85 μΩ·m

Comparison with Common Stainless Steel Grades

Property	Duplex 2205	316L	304
Yield Strength	450-550 MPa ✓	220-240 MPa	210-230 MPa
PREN Value	35-38 ✓	24-26	18-20
Chloride SCC Resistance	Excellent ✓	Moderate	Poor
Cost (Relative)	1.0× ✓	1.2-1.3×	0.8×
Magnetic	Yes (Ferritic)	No ✓	No ✓

Common Applications in Australia

Marine & Offshore

• Seawater pumps and valves
• Offshore platform equipment
• Desalination plants
• Marine fasteners and fittings
• Heat exchangers
• Propeller shafts

Oil & Gas

• Subsea equipment
• Pipeline systems
• Pressure vessels
• Manifolds and headers
• Wellhead equipment
• Process piping

Chemical Processing

• Reaction vessels
• Storage tanks
• Piping systems
• Agitators and mixers
• Heat transfer equipment
• Chlorine handling systems

Food & Beverage

• Brewery equipment
• Processing vessels
• Storage tanks
• Conveyor systems
• CIP systems
• Dairy processing equipment

Water Treatment

• Wastewater treatment plants
• Reverse osmosis systems
• Filtration equipment
• Pumps and valves
• Chlorination systems
• Storage and distribution

Industrial

• Paper and pulp mills
• Mining equipment
• Structural components
• Fasteners and fittings
• Power generation
• Architectural applications

CNC Machining Duplex 2205

Machining Characteristics

Higher Hardness

Duplex 2205 is harder than austenitic grades (290 HB vs 200 HB for 316L), requiring carbide or coated tooling.

Work Hardening

Lower work hardening rate than austenitic stainless steels, but still requires sharp tools and consistent feed rates.

Chip Formation

Produces shorter chips than austenitic grades due to ferritic content, improving chip evacuation and surface finish.

Tool Wear

Higher tool wear than 304/316, but lower than super duplex grades. Regular tool monitoring essential for quality.

Recommended Parameters

Operation	Speed	Feed
Turning (HSS)	25-35 m/min	0.15-0.40 mm/rev
Turning (Carbide)	60-100 m/min	0.20-0.50 mm/rev
Milling (HSS)	15-25 m/min	0.10-0.25 mm/tooth
Milling (Carbide)	50-90 m/min	0.15-0.35 mm/tooth
Drilling (HSS)	10-20 m/min	0.10-0.20 mm/rev
Drilling (Carbide)	30-50 m/min	0.15-0.30 mm/rev

Coolant: Use of coolant is essential. Water-soluble coolants or sulfur-chlorine cutting oils recommended for optimal tool life and surface finish.

Best Practices for Duplex 2205 Machining

Do's

✓ Use carbide or coated carbide tooling for best results
✓ Maintain consistent feed rates to avoid work hardening
✓ Use positive rake angles (6-8°) to reduce cutting forces
✓ Apply generous coolant for heat dissipation
✓ Ensure machine rigidity to minimize vibration
✓ Use sharp tools and replace before excessive wear
✓ Climb mill when possible for better surface finish
✓ Monitor tool wear regularly during long runs

Don'ts

✗ Avoid intermittent cuts that create work-hardened layers
✗ Don't use worn or damaged tools
✗ Avoid excessively high cutting speeds
✗ Don't allow tools to dwell or rub on surface
✗ Avoid inadequate coolant application
✗ Don't use negative rake angles (increases forces)
✗ Avoid light cuts that cause rubbing rather than cutting
✗ Don't ignore chip evacuation - poor evacuation damages surface

Welding & Heat Treatment

Welding Guidelines

Suitable Welding Processes

• GTAW (TIG) - Excellent for thin sections and root passes
• GMAW (MIG) - Good for thicker sections and production
• SMAW (Stick) - Field welding and repair work
• SAW - High deposition rate for thick plates

Filler Material

AWS ER2209 (25% Cr, 9% Ni, 3% Mo, 0.16% N) provides balanced weld metal microstructure and corrosion resistance matching base material.

Key Parameters

• Interpass temperature: 60-150°C maximum
• Heat input: 0.5-2.5 kJ/mm
• No preheating required
• Post-weld heat treatment not required

Heat Treatment

Solution Annealing

• Temperature: 1020-1100°C
• Holding time: Varies by thickness (typically 2-10 min)
• Cooling: Water quench or rapid air cool
• Purpose: Restore corrosion resistance after welding

Stress Relief (If Required)

• Temperature: 300-400°C maximum
• Time: 1-2 hours
• Caution: Avoid 300-1000°C range (precipitation)

Important Notes

• Avoid prolonged exposure at 300-1000°C
• Risk of sigma phase and chi phase formation
• Embrittlement and corrosion resistance reduction
• Most applications don't require heat treatment

Ready to Work with Duplex 2205 Stainless Steel?

Fedele Autocore provides expert CNC machining services for Duplex 2205 components across Australia. Our experience with challenging materials and precision manufacturing ensures your parts meet the highest quality standards.

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