Alloy 20 / 020，Carpenter 20Cb-3 ，UNS N08020,E FORU

British Specs:，American Specs:，German Specs: WS 2.4660

**Product Name:** Alloy 20 / UNS N08020 / Carpenter 20Cb-3 **Material Type:** Nickel-Iron-Chromium Super Austenitic Stainless Steel **Standard:** ASTM B463, B464, B729 | ASME SB463, SB464, SB729 --- ### **Overview** Alloy 20 (UNS N08020), commercially known as **Carpenter 20Cb-3**, is a nickel-iron-chromium super austenitic stainless steel specifically developed to resist sulfuric acid corrosion and general chemical attack. This alloy combines excellent corrosion resistance with good mechanical properties and fabrication characteristics, making it a preferred material for chemical processing equipment and aggressive service environments. --- ### **Key Advantages** - **Excellent Sulfuric Acid Resistance:** Specifically designed for sulfuric acid service - **Superior Chloride Stress Corrosion Cracking Resistance:** Outperforms conventional stainless steels - **Good General Corrosion Resistance:** Suitable for wide range of corrosive media - **Excellent Mechanical Properties:** High strength and good ductility - **Good Fabricability:** Can be welded and formed using standard methods - **Oxidation Resistance:** Suitable for high-temperature applications --- ### **Chemical Composition (Typical Weight %)** | Element | Content (%) | Element | Content (%) | |---------|-------------|---------|-------------| | Nickel (Ni) | 32.0-38.0 | Chromium (Cr) | 19.0-21.0 | | Iron (Fe) | Balance | Molybdenum (Mo) | 2.0-3.0 | | Copper (Cu) | 3.0-4.0 | Manganese (Mn) | ≤2.0 | | Silicon (Si) | ≤1.0 | Carbon (C) | ≤0.07 | | Niobium (Nb) | 8×C-1.0 | Phosphorus (P) | ≤0.045 | | Sulfur (S) | ≤0.035 | | | --- ### **Physical & Mechanical Properties** #### **Physical Properties** - **Density:** 8.08 g/cm³ (0.292 lb/in³) - **Melting Point:** 1440-1500°C (2620-2730°F) - **Thermal Expansion Coefficient:** 15.9 × 10⁻⁶/°C (20-100°C) - **Modulus of Elasticity:** 186 GPa (27 × 10⁶ psi) - **Thermal Conductivity:** 12.9 W/m·K at 100°C - **Electrical Resistivity:** 0.90 μΩ·m at 20°C #### **Mechanical Properties (Room Temperature)** | Property | Typical Value | |----------|---------------| | Tensile Strength | 620-690 MPa (90-100 ksi) | | Yield Strength (0.2% Offset) | 300-415 MPa (44-60 ksi) | | Elongation | 30-50% | | Hardness | 150-190 HB | | Reduction of Area | 50-70% | --- ### **Corrosion Resistance** #### **Chemical Resistance** - **Excellent Resistance:** Sulfuric acid of all concentrations up to 95°C - **Good Resistance:** Phosphoric acid, nitric acid, organic acids - **Chloride Resistance:** Superior to Type 316 and 317 stainless steels - **Pitting & Crevice Corrosion:** Good resistance in chloride environments #### **Special Features** - Niobium stabilization prevents carbide precipitation - Copper addition enhances sulfuric acid resistance - Balanced composition prevents stress corrosion cracking --- ### **International Standards** #### **Material Standards** - **ASTM B463:** Sheet, Plate, and Strip - **ASTM B464:** Welded Pipe - **ASTM B729:** Seamless and Welded Tube - **ASTM B473:** Bar and Wire - **ASTM B366:** Fittings #### **International Equivalents** - **UNS:** N08020 - **Werkstoff Nr.:** 2.4660 - **ISO:** NiCr20CuMo (Proposed) --- ### **Applications** #### **Chemical Processing** - Sulfuric acid pickling tanks and heating coils - Chemical processing reactors and vessels - Phosphoric acid evaporators - Process piping and heat exchangers - Mixing tanks and storage vessels #### **Pharmaceutical & Food** - Process equipment requiring high purity - Acid handling systems - CIP (Clean-in-Place) systems #### **Industrial Applications** - Acid production plants - Petrochemical processing - Plastic manufacturing - Synthetic fiber production - Industrial heating systems #### **Specific Components** - Pump shafts and impellers - Valve bodies and trim - Fasteners and fittings - Heat exchanger tubes - Distillation column internals --- ### **Fabrication & Processing** #### **Heat Treatment** - **Solution Annealing:** 925-1010°C (1700-1850°F) followed by rapid cooling - **Stress Relieving:** Not generally required #### **Welding** - **Recommended Methods:** GTAW, GMAW, SMAW - **Filler Metals:** Alloy 20 or nickel-base alloys - **Precautions:** Maintain low heat input, avoid contamination #### **Machining & Forming** - **Machining:** Similar to Type 304/316 but work hardens rapidly - **Forming:** Good cold working characteristics - **Cutting:** Use sharp tools with positive rake angles --- ### **Quality Assurance** #### **Testing & Certification** - Chemical analysis certification - Mechanical property testing - Corrosion testing per applicable standards - Non-destructive testing as required - Mill test reports provided #### **Quality Standards** - NACE MR0175/ISO 15156 compliance - PED 2014/68/EU certification available - Nuclear and aerospace qualifications upon request --- ### **Product Forms Available** - Sheet and Plate - Bar and Wire - Pipe and Tubing - Fittings and Flanges - Fasteners - Forged Products --- ### **Conclusion** Alloy 20/UNS N08020/Carpenter 20Cb-3 represents a superior choice for applications involving sulfuric acid and other aggressive chemical environments. Its unique combination of nickel, chromium, molybdenum, and copper, stabilized with niobium, provides exceptional corrosion resistance while maintaining good mechanical properties and fabricability. This alloy continues to be the material of choice for critical chemical processing equipment worldwide, offering reliable performance and long service life in demanding applications. --- *Carpenter 20Cb-3® is a registered trademark of Carpenter Technology Corporation. All technical data are typical values and should be verified for specific applications. Consult manufacturer's specifications for project-specific requirements.*

Packing of Standard Packing: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 2664 gallon liquid totes Special package is available on request.