AISI Alloy 20 Stainless Steel Plate | Alloy 20 China steel mill-Direct Supply
What is AISI Alloy 20 Stainless Steel?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI Alloy 20 Stainless Steel Plate.
Alloy 20 is widely known and searched under many different names and designations, including Alloy 20, AISI Alloy 20, UNS N08020, 20Cb-3, Alloy 20Cb-3, Carpenter 20, Nickel Alloy 20, and CN7M (related cast grade). All these refer to the same high-performance nickel-iron-chromium austenitic alloy.
Alloy 20 contains high levels of nickel (32–38%), chromium (19–21%), molybdenum (2–3%) and copper (3–4%). This unique combination provides outstanding resistance to sulfuric acid across a wide range of concentrations and temperatures, as well as excellent resistance to general corrosion, pitting and stress corrosion cracking in many aggressive chemical environments. The addition of niobium helps stabilize the alloy against intergranular corrosion.
Alloy 20 is non-magnetic in the annealed condition and is extensively used in chemical processing, pharmaceutical, food, and pollution control industries where resistance to sulfuric acid and mixed acids is critical.
SHH STEEL supplies Alloy 20 as true China steel mill-Direct Supply, sourcing directly from major Chinese stainless steel and nickel alloy mills. This model delivers competitive mill pricing, consistent quality, complete heat traceability and reliable delivery. SHH STEEL offers Alloy 20 in plate and sheet form across a practical range of thicknesses and surface finishes.
Alloy 20 is frequently compared with a240 316l, a240 317l, a240 904l, a240 2205 and a240 2507 when selecting materials for highly corrosive chemical service. SHH STEEL provides technical support to help customers choose the most appropriate grade.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Grade | Alloy 20 / UNS N08020 / 20Cb-3 | Confirmed |
| Related Standards | ASTM B463, ASTM B473, ASTM A240 (related), ASME | Available |
| Product Form | Plate, Sheet | Available |
| Delivery Condition | Solution Annealed | Standard |
| Thickness Range | 0.5 mm – 50 mm (thicker available on request) | Custom sizes supported |
| Width | Up to 1500–2000 mm | Available |
| Length | Up to 6000 mm or cut-to-length | Available |
| Surface Finish | 2B, No.1, and others on request | Available |
| Certification | EN 10204 3.1 / Mill Test Certificate | Available |
SHH STEEL can supply Alloy 20 dual-certified to relevant ASTM/ASME specifications when required by the project.
Chemical Composition
Typical Chemical Composition of Alloy 20 (UNS N08020):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.07 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.035 |
| Chromium (Cr) | 19.00 – 21.00 |
| Nickel (Ni) | 32.00 – 38.00 |
| Molybdenum (Mo) | 2.00 – 3.00 |
| Copper (Cu) | 3.00 – 4.00 |
| Niobium (Nb/Cb) | 8 × C min – 1.00 max |
| Iron (Fe) | Balance |
The high nickel, copper and molybdenum contents are the key features that give Alloy 20 its outstanding resistance to sulfuric acid and many aggressive chemical media. Niobium stabilization further improves resistance to intergranular corrosion. SHH STEEL carefully controls composition to ensure consistent high-performance results.
Mechanical Properties
Annealed Condition (typical values)
| Property | Value |
|---|---|
| Tensile Strength | ≥ 550 MPa |
| Yield Strength (0.2%) | ≥ 240 MPa |
| Elongation (in 50 mm) | ≥ 30% |
| Hardness | ≤ 217 HB |
Alloy 20 offers good strength combined with excellent ductility and toughness. SHH STEEL supplies material with consistent mechanical properties suitable for fabrication and welding in highly corrosive chemical service.
Physical Properties Density is approximately 8.05–8.10 g/cm³. The grade is non-magnetic in the annealed condition. Melting range is approximately 1350–1425°C.
Material Comparison
| Grade | Ni (%) | Mo (%) | Cu (%) | Sulfuric Acid Resistance | Pitting Resistance | Typical Preference |
|---|---|---|---|---|---|---|
| AISI 316L | 10–14 | 2.0–3.0 | — | Limited | Better | General chloride service |
| AISI 317L | 11–15 | 3.0–4.0 | — | Moderate | Superior | Aggressive chloride service |
| AISI 904L | 23–28 | 4.0–5.0 | 1.0–2.0 | Good | Excellent | Aggressive chloride & acid |
| Alloy 20 | 32–38 | 2.0–3.0 | 3.0–4.0 | Outstanding | Very Good | Sulfuric acid & mixed chemical service |
| AISI 2205 | 4.5–6.5 | 3.0–3.5 | — | Moderate | Excellent | High strength + chloride resistance |
| AISI 2507 | 6–8 | 3.0–5.0 | — | Moderate | Outstanding | Super duplex severe service |
Alloy 20 (also known as UNS N08020, 20Cb-3, Carpenter 20 and Alloy 20Cb-3) is specifically optimized for sulfuric acid service and outperforms both a240 316l and a240 904l in many sulfuric acid environments. When higher strength is also required, SHH STEEL recommends evaluating duplex or super duplex grades such as a240 2205 and a240 2507.
Corrosion Resistance
Alloy 20 offers outstanding resistance to sulfuric acid across a broad range of concentrations and temperatures. It also provides excellent resistance to phosphoric acid, nitric acid mixtures, and many organic and inorganic acids. The high nickel and copper contents contribute to good resistance to stress corrosion cracking and pitting in chloride-containing environments.
It is particularly effective in chemical processing equipment handling sulfuric acid, mixed acids, and aggressive process streams where conventional stainless steels fail. In extremely aggressive oxidizing chloride environments, more specialized alloys or super duplex grades may still be required. SHH STEEL can assist in material selection based on the specific service conditions.
Weldability
Alloy 20 has good weldability. Matching Alloy 20 or appropriate nickel-based filler metals are recommended. The niobium stabilization provides good resistance to intergranular corrosion in the as-welded condition. Post-weld heat treatment is generally not required for most applications.
SHH STEEL recommends controlled heat input and proper post-weld cleaning to achieve optimum corrosion performance in aggressive chemical service.
Heat Treatment
Alloy 20 is normally supplied in the solution-annealed condition by SHH STEEL.
Recommended solution annealing temperature range is 925–1010°C (or as specified by the mill), followed by rapid cooling. Proper annealing optimizes corrosion resistance and ductility. SHH STEEL controls heat treatment to ensure consistent high-performance results.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| 2B | Cold-rolled, annealed, pickled, skin-passed | Alloy 20 2B – most common for general fabrication |
| No.1 | Hot-rolled, annealed and pickled | Alloy 20 No.1 – industrial plate |
| Special | Ground or custom finishes | Alloy 20 Special – on request |
SHH STEEL regularly supplies Alloy 20 in 2B and No.1 finishes, and can provide other finishes according to project requirements.
Tolerances
Dimensional tolerances for Alloy 20 Stainless Steel Plate supplied by SHH STEEL generally conform to applicable ASTM standards.
Typical available size range is thickness 0.5 mm – 50 mm, width up to 1500–2000 mm, and length up to 6000 mm or cut-to-length. SHH STEEL provides precise dimensional control and can support tighter tolerances when required.
Equivalent Material Grades
| Grade / Designation | Standard / Region | Notes |
|---|---|---|
| Alloy 20 | — | — |
| UNS N08020 | Unified Numbering System | Most common UNS designation |
| 20Cb-3 / Alloy 20Cb-3 | Commercial | Common trade names |
| Carpenter 20 | Commercial | Historical / commercial name |
| Related CN7M | Cast grade | Closely related cast equivalent |
| Related high-Ni grades | EN / JIS / GB | Approximate national equivalents |
Related grades for comparison include a240 316l, a240 317l, a240 904l, a240 2205 and a240 2507.
Applications
Alloy 20 (also called as UNS N08020, 20Cb-3, Carpenter 20 and Alloy 20Cb-3) is selected for highly corrosive chemical environments, especially those involving sulfuric acid. Typical applications of Alloy 20 include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Chemical & Process Industry | Alloy 20 tanks, vessels, reactors, piping and process equipment |
| Sulfuric Acid Handling | Alloy 20 equipment for sulfuric acid production and handling |
| Pharmaceutical | Alloy 20 clean equipment, vessels and piping |
| Food & Pickling | Alloy 20 equipment in food processing and pickling lines |
| Pollution Control | Alloy 20 scrubbers and components in aggressive gas streams |
| Plastics & Synthetic Fibers | Alloy 20 process equipment in chemical synthesis |
| General Corrosive Service | Alloy 20 heat exchangers, pumps and welded structures |
SHH STEEL supplies Alloy 20 for these highly demanding corrosive applications with consistent quality. For related industry solutions, see our petrochemical industry and equipment manufacturing pages. Supporting services include steel cutting services and steel welding services.
Why Choose SHH STEEL
SHH STEEL is a China steel mill-Direct Supply specializing in stainless steel and nickel alloy plate and sheet. By working directly with major Chinese mills, SHH STEEL supplies Alloy 20 with the following advantages:
- Genuine China steel mill-Direct Supply pricing
- Consistent quality and complete heat traceability
- Full Mill Test Certificates (EN 10204 3.1)
- High-performance Alloy 20 material optimized for sulfuric acid and aggressive chemical service
- Flexible dimensions and surface finishes (including Alloy 20 2B and Alloy 20 No.1)
- Technical support for selection among 316L, 317L, 904L, Alloy 20 and duplex grades
- Value-added services including steel cutting services, steel welding services and worldwide shipping service
For more information about our company and full product range, please visit China steel Mill Agent-SHH STEEL.
FAQ
- What are the other common names for Alloy 20?Alloy 20 is also widely known as UNS N08020, 20Cb-3, Alloy 20Cb-3, Carpenter 20 and Nickel Alloy 20. SHH STEEL can supply material certified to the required designation.
- What is the main advantage of Alloy 20 over 316L or 904L?Alloy 20 offers outstanding resistance to sulfuric acid across a wide concentration and temperature range, outperforming both 316L and 904L in many sulfuric acid environments. SHH STEEL recommends Alloy 20 when sulfuric acid resistance is the primary requirement.
- Is Alloy 20 a stainless steel or a nickel alloy?Alloy 20 is a nickel-iron-chromium austenitic alloy often classified as a super austenitic stainless steel or nickel alloy. SHH STEEL supplies it under the common commercial and UNS designations.
- Is Alloy 20 magnetic?Non-magnetic in the annealed condition. SHH STEEL supplies fully annealed material as standard.
- What is the density of Alloy 20?Approximately 8.05–8.10 g/cm³. SHH STEEL provides material certificates confirming physical and mechanical properties.
- Can Alloy 20 be welded easily?Yes. It has good weldability. Matching Alloy 20 or appropriate nickel-based filler metals are recommended. SHH STEEL advises proper procedures for critical chemical service.
- Does SHH STEEL supply dual-certified Alloy 20 material?Yes, SHH STEEL commonly supplies dual-certified material upon request.
Conclusion
Alloy 20 Stainless Steel Plate (also known as UNS N08020, 20Cb-3, Carpenter 20 and Alloy 20Cb-3) is a high-performance nickel-iron-chromium alloy that offers outstanding resistance to sulfuric acid and excellent general corrosion resistance in aggressive chemical environments. It is the preferred material for chemical processing, pharmaceutical, food and pollution control applications involving sulfuric acid and mixed acids.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality Alloy 20 Stainless Steel Plate with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including Alloy 20 2B and Alloy 20 No.1), or a competitive quotation.
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