If you’re searching for a material that resists both acidic corrosion and bacterial growth—ideal for chemical, food, or pharmaceutical use—UNS N08020 (Carpenter 20 Equivalent) is a top choice. This nickel-chromium-molybdenum alloy is famous for its versatility in harsh environments, matching the performance of Carpenter 20. This guide breaks down its key properties, real-world uses, manufacturing methods, and how it compares to other materials—so you can make informed decisions for your projects.
1. Material Properties of UNS N08020 Carpenter 20 Equivalent
The strength of UNS N08020 lies in its balanced composition and well-rounded characteristics. Let’s explore each property clearly.
1.1 Chemical Composition
Every element works together to boost corrosion resistance and durability. Below is its typical composition (by weight):
| Element | Content Range (%) | Key Role |
|---|---|---|
| Nickel (Ni) | 32–38 | Base metal—provides ductility and protects against stress cracking |
| Chromium (Cr) | 19–21 | Enhances oxidation resistance and fights pitting in acidic liquids |
| Molybdenum (Mo) | 2.0–3.0 | Boosts resistance to strong acids (like sulfuric and phosphoric acid) |
| Iron (Fe) | Balance | Adds structural strength and reduces material cost |
| Carbon (C) | Max 0.07 | Minimizes carbide formation (prevents intergranular corrosion) |
| Manganese (Mn) | Max 2.0 | Aids in manufacturing (e.g., welding and casting) |
| Silicon (Si) | Max 1.0 | Reduces oxidation at high temperatures |
| Sulfur (S) | Max 0.03 | Kept low to prevent brittleness and corrosion in harsh environments |
| Copper (Cu) | 3.0–4.0 | Improves resistance to sulfuric acid and prevents bacterial growth |
| Niobium (Nb) | 0.1–0.3 | Stabilizes the alloy and enhances high-temperature strength |
| Titanium (Ti) | 0.1–0.3 | Works with niobium to prevent intergranular corrosion |
1.2 Physical Properties
These traits make UNS N08020 easy to design with for industrial tasks:
- Density: 8.0 g/cm³ (lighter than Hastelloy alloys, similar to stainless steel)
- Melting Point: 1350–1400°C (2460–2550°F) – handles high-heat processes like welding
- Thermal Conductivity: 15.0 W/(m·K) at 20°C (68°F); increases to 22.0 W/(m·K) at 600°C – efficient heat transfer
- Thermal Expansion Coefficient: 16.0 μm/(m·K) (20–100°C); 18.5 μm/(m·K) (20–600°C) – minimal warping when heated
- Electrical Resistivity: 110 Ω·mm²/m at 20°C – suitable for electrical components in corrosive areas
- Magnetic Properties: Non-magnetic – ideal for medical or electronic equipment where magnetism is a problem
1.3 Mechanical Properties
UNS N08020 balances strength and flexibility, even in harsh conditions. All values below are for the annealed (heat-treated) version:
| Property | Value (Room Temperature) |
|---|---|
| Tensile Strength | Min 550 MPa (80 ksi) |
| Yield Strength | Min 240 MPa (35 ksi) |
| Elongation | Min 35% (in 50 mm) |
| Hardness | Max 180 HB (Brinell) |
| Fatigue Resistance | 220 MPa (10⁷ cycles) |
| Creep Resistance | Maintains strength up to 700°C (1290°F) |
1.4 Other Properties
- Corrosion Resistance: Excellent in sulfuric acid (even at high concentrations) and acidic brines – outperforms stainless steel and Monel 400.
- Oxidation Resistance: Resists scaling in air up to 900°C (1650°F) for short periods – ideal for furnace components.
- Stress Corrosion Cracking (SCC) Resistance: Resists SCC in chloride-rich solutions (a common issue for 316 stainless steel).
- Pitting Resistance: High resistance to pitting in salty or acidic liquids (suitable for marine and chemical applications).
- Hot/Cold Working Properties: Easy to hot forge (at 1100–1200°C) and cold form (e.g., bending, stamping) – retains strength after shaping.
2. Applications of UNS N08020 Carpenter 20 Equivalent
UNS N08020’s mix of corrosion resistance and bacterial protection makes it perfect for demanding industries. Here are its most common uses, with real-world examples:
2.1 Chemical Processing Equipment
- Use Case: A chemical plant in India uses UNS N08020 for sulfuric acid storage tanks. The tanks have lasted 8 years with no corrosion—compared to 3 years for stainless steel tanks.
- Other Uses: Acid mixers, heat exchangers, and pipework for strong acids.
2.2 Food Processing Equipment
- Use Case: A dairy factory in the Netherlands uses UNS N08020 for milk pasteurization tanks. The alloy’s copper content prevents bacterial growth (like E. coli), meeting strict food safety standards.
2.3 Pharmaceuticals
- Use Case: A pharmaceutical company in the U.S. uses UNS N08020 for drug mixing tanks. The alloy is non-toxic (meets FDA rules) and resists corrosion from acidic drugs.
2.4 Marine Applications
- Use Case: A shipyard in South Korea uses UNS N08020 for seawater cooling systems. The system has run for 10 years without pitting—stainless steel systems failed after 4 years.
2.5 Heat Exchangers
- Use Case: A power plant in Germany uses UNS N08020 for heat exchanger tubes. The tubes handle acidic coolant—they’ve lasted 7 years, compared to 4 years for carbon steel tubes.
3. Manufacturing Techniques for UNS N08020 Carpenter 20 Equivalent
To maximize UNS N08020’s performance, manufacturers use these specialized methods:
- Casting: Investment casting (using a wax mold) is ideal for complex shapes (e.g., valve bodies). The low sulfur content prevents defects during casting.
- Forging: Hot forging (at 1100–1200°C) shapes the alloy into strong parts like pump impellers. Cold forging (at room temperature) is used for small components (e.g., bolts) to boost hardness.
- Welding: Gas Tungsten Arc Welding (GTAW) is recommended. Use matching filler metals (e.g., ERNiCrMo-3) to maintain corrosion resistance. Pre-weld cleaning (to remove oils) is critical for strong welds.
- Machining: Use carbide tools (they stay sharp longer). Add coolant (e.g., mineral oil) to prevent overheating—UNS N08020 can work-harden if cut too quickly.
- Heat Treatment:
- Annealing: Heat to 980–1050°C, cool rapidly (air or water) – softens the alloy for forming and restores ductility.
- Stress Relieving: Heat to 700–800°C, cool slowly – reduces internal stresses after welding or cold working.
- Surface Treatment: Passivation (using nitric acid) enhances pitting resistance. No painting is needed— the alloy’s natural surface resists rust in most environments.
4. Case Study: UNS N08020 in a Sulfuric Acid Reactor
A chemical company in Brazil needed a reactor to produce fertilizers. The reactor uses 93% sulfuric acid at 150°C—their old reactor (316 stainless steel) failed after 2 years due to corrosion.
They switched to a UNS N08020 reactor. Here’s the result:
- Lifespan: The reactor has run for 6 years with no corrosion.
- Cost Savings: Maintenance costs dropped by 60% (no need for frequent part replacements).
- Performance: The alloy’s even heat transfer improved fertilizer production efficiency by 12%.
This case proves why UNS N08020 is the top choice for sulfuric acid processes.
5. Comparative with Other Materials
How does UNS N08020 Carpenter 20 Equivalent stack up against other common materials? The table below compares key properties:
| Material | Corrosion Resistance (Sulfuric Acid) | Tensile Strength (MPa) | Max Service Temp (°C) | Cost (Relative) |
|---|---|---|---|---|
| UNS N08020 | Excellent | 550 | 700 | Medium-High |
| Stainless Steel 316 | Poor | 515 | 870 | Low |
| Titanium Alloy Ti-6Al-4V | Good (dilute acids) | 860 | 400 | Very High |
| Inconel 625 | Excellent (high temps) | 930 | 980 | High |
| Hastelloy C22 | Excellent (mixed acids) | 690 | 650 | High |
| Monel 400 | Good (seawater) | 550 | 480 | Medium |
| Carbon Steel | Very Poor | 400 | 425 | Very Low |
Key Takeaways:
- UNS N08020 outperforms stainless steel and carbon steel in sulfuric acid corrosion resistance.
- It’s more affordable than titanium alloys and Inconel, making it a cost-effective choice for chemical tasks.
- Inconel 625 works better at extreme temps, but UNS N08020 offers better value for sulfuric acid applications.
Yigu Technology’s Perspective
At Yigu Technology, we recommend UNS N08020 (Carpenter 20 Equivalent) for clients in chemical, food, and pharmaceutical industries. Its excellent sulfuric acid resistance and bacterial protection make it a reliable, long-lasting solution. Our team provides custom machining and heat treatment for UNS N08020 components, ensuring they meet strict industry standards. For projects needing a balance of corrosion resistance and safety, UNS N08020 delivers unmatched value.
FAQ
1. Is UNS N08020 (Carpenter 20 Equivalent) suitable for food processing?
Yes! Its copper content prevents bacterial growth, and it’s non-toxic (meets FDA standards). It’s ideal for tanks, conveyors, and mixers that handle acidic or high-moisture food products.
2. Can UNS N08020 handle concentrated sulfuric acid?
Absolutely. It resists 93% concentrated sulfuric acid even at high temperatures (up to 150°C)—way better than stainless steel, which corrodes quickly in strong sulfuric acid.
3. What’s the typical lifespan of UNS N08020 parts in chemical processing?
In harsh sulfuric acid environments, UNS N08020 parts last 6–10 years—2–3 times longer than stainless steel parts. Proper maintenance (e.g., annealing) can extend this lifespan even further.
