Alloy 20
Alloy 20 Supplier in Tunisia
Introduction
Alloy 20, also known as Carpenter 20, is a corrosion-resistant austenitic iron-nickel-chromium alloy containing molybdenum and copper. Identified by UNS N08020, it was developed for applications involving aggressive chemical environments, particularly selected sulfuric acid services.
The combination of nickel, chromium, molybdenum, and copper provides useful corrosion resistance in many chemical-processing applications. Alloy 20 is used in chemical and petrochemical plants, pharmaceutical manufacturing, industrial processing equipment, and selected heat-transfer systems.
Emirerri Steel supplies industrial metal products, piping materials, and corrosion-resistant alloys for customers in Tunisia, North Africa, and international markets, subject to availability and confirmation of product specifications.
Key Properties
- Corrosion resistance: Performs well in many suitable chemical environments.
- Sulfuric acid resistance: Used in selected sulfuric acid processing applications, depending on concentration and temperature.
- Resistance to localized corrosion: Molybdenum helps to protect against pitting in particular situations.
- Copper addition: Supports corrosion performance in selected acidic media.
- Mechanical strength: Suitable for many industrial equipment applications when designed to the applicable requirements.
- Fabricability: Can be formed, machined, and manufactured using appropriate procedures.
- Weldability: Generally weldable with compatible filler metals and qualified procedures.
- Industrial versatility: Used for selected tanks, piping systems, pumps, valves, and heat exchangers.
Actual performance depends on chemical concentration, temperature, impurities, fluid velocity, and operating conditions. Alloy 20 is not universally resistant to every acid or corrosive medium.
Alloy 20 Chemical Composition
The following table provides commonly referenced composition limits for Alloy 20. Verify the exact requirements against the applicable product specification and material test certificate.
| Element | Composition (wt. %) |
|---|---|
| Nickel (Ni) | 32.0–38.0 |
| Chromium (Cr) | 19.0–21.0 |
| Copper (Cu) | 3.0–4.0 |
| Molybdenum (Mo) | 2.0–3.0 |
| Iron (Fe) | Balance |
| Manganese (Mn) | 2.0 max |
| Silicon (Si) | 1.0 max |
| Carbon (C) | 0.07 max |
| Niobium + Tantalum (Nb + Ta) | 8 × C min to 1.0 max |
| Phosphorus (P) | 0.045 max |
| Sulfur (S) | 0.035 max |
Note: Confirm the chemistry limits against the governing specification, product form, and contractual requirements.
Alloy 20 Mechanical Properties
Mechanical properties vary according to product form, dimensions, manufacturing process, and metallurgical condition.
| Property | Indicative Value |
|---|---|
| Tensile Strength | Approximately 480–650 MPa |
| Yield Strength (0.2% offset) | Approximately 200–350 MPa |
| Elongation | Approximately 25–40% |
| Hardness | Depends on product form and condition |
These figures are indicative reference ranges, not guaranteed acceptance values. Engineering design and inspection should use the relevant product standard and certified test results.
Alloy 20 Physical Properties
| Property | Approximate Value |
|---|---|
| Density | 8.0–8.1 g/cm³ |
| Melting Range | Approximately 1,380–1,400°C |
| Young’s Modulus | Approximately 190–200 GPa |
| Thermal Conductivity | Approximately 10–15 W/m·K |
| Thermal Expansion | Depends on the temperature range |
These are general reference values. Use applicable technical data for calculations involving specific temperatures and operating conditions.
Standards and Specifications
Applicable standards depend on the product form and intended use. Commonly referenced specifications include:
| Product Form | Commonly Referenced Standard |
|---|---|
| Sheet, strip, and plate | ASTM B463 |
| Seamless pipe and tube | ASTM B729 |
| Welded pipe and tube | ASTM B464 or ASTM B468, depending on product type |
| Bars and other wrought products | Verify the applicable product-specific specification |
| Forgings and fittings | Confirm the relevant specification for the product form |
The precise standard must be confirmed for each product. Not every specification covers all dimensions, manufacturing routes, or delivery conditions.
Equivalent Grades
| Standard / System | Designation |
|---|---|
| UNS | N08020 |
| Commercial Designation | Alloy 20 |
| Alternative Name | Carpenter 20 |
| Werkstoff Number | Commonly associated with 2.4660; verify against the applicable standard |
| Material Classification | Austenitic iron-nickel-chromium alloy with molybdenum and copper |
Equivalent designations should be verified against the applicable standard, chemical composition, product form, and required mechanical properties. Similar designations do not guarantee complete interchangeability.
Available Forms
Depending on manufacturing capability and availability, Alloy 20 may be supplied in the following forms:
- Alloy 20 round bars and rods
- Alloy 20 flat bars
- Alloy 20 sheets and plates
- Alloy 20 strips and coils
- Alloy 20 seamless pipes and tubes
- Alloy 20 welded pipes and tubes
- Forged parts and Alloy 20 fittings, subject to specification
- Alloy 20 machined components, where feasible
Dimensions, tolerances, surface finish, quantities, inspection requirements, and certification must be confirmed during quotation.
Corrosion Resistance
Alloy 20 is particularly associated with selected sulfuric acid environments. Its nickel and copper content contributes to corrosion performance in suitable acidic conditions, while chromium and molybdenum support resistance in certain corrosive environments.
However, resistance depends strongly on acid concentration, temperature, aeration, contaminants, and flow conditions. Certain chloride-containing, oxidizing, or highly aggressive environments may require a different material.
Before selecting Alloy 20 for critical equipment, assess the complete process chemistry and operating conditions. Material compatibility should be established using reliable corrosion data or specialist engineering evaluation.
Heat Resistance and Temperature Performance
Alloy 20 can be used in selected industrial applications involving elevated temperatures, provided its mechanical properties and corrosion performance remain suitable for the intended service.
The melting range does not represent the maximum permissible operating temperature. Design limits must be determined from the applicable code, pressure and loading conditions, corrosion data, and certified material properties.
Heat Treatment and Fabrication
Alloy 20 can be formed, machined, and fabricated using methods suitable for austenitic corrosion-resistant alloys. Cold working may cause work hardening, which should be considered during forming operations.
Where heat treatment is required, the procedure must follow the applicable product specification and qualified manufacturing instructions. Processing parameters depend on product form, initial condition, and required final properties.
Welding of Alloy 20
Alloy 20 is generally weldable using appropriate welding processes and compatible filler metals. Proper surface preparation, cleanliness, joint design, and filler selection are important for achieving reliable weld quality and corrosion performance.
For pressure equipment and critical chemical-processing installations, welding should follow qualified procedures, applicable construction codes, and agreed inspection requirements.
Alloy 20 vs Stainless Steel 316L
Alloy 20 and stainless steel 316L are both corrosion-resistant materials, but their compositions and suitability for chemical environments differ.
| Characteristic | Alloy 20 | Stainless Steel 316L |
|---|---|---|
| UNS Designation | N08020 | S31603 |
| Main Alloy System | Iron-nickel-chromium with copper and molybdenum | Iron-chromium-nickel-molybdenum |
| Nickel Content | Approximately 32–38% | Typically lower |
| Copper Addition | Yes | Not a principal alloying addition |
| Sulfuric Acid Applications | Suitable for selected conditions | Suitability depends strongly on concentration and temperature |
| Typical Uses | Selected chemical-processing equipment | General chemical, food-processing, marine, and industrial equipment |
Neither alloy is suitable for every corrosive environment. Selection should be based on the actual chemical medium, temperature, concentration, design conditions, and applicable standards.
Applications
Alloy 20 is used in several industrial sectors:
Chemical processing: Tanks, vessels, piping systems, and process equipment.
Sulfuric acid plants: Selected equipment operating within suitable concentration and temperature limits.
Petrochemical industry: Components chosen according to process chemistry and corrosion requirements.
Pharmaceutical manufacturing: Process equipment where material compatibility and cleanliness requirements are satisfied.
Food processing: Selected components where the alloy meets applicable hygiene and regulatory requirements.
Heat exchangers: Tubes and related components used in compatible chemical environments.
Pumps and valves: Components designed for suitable corrosive fluid services.
Industrial manufacturing: Fabricated parts requiring corrosion resistance and appropriate mechanical properties.
Final material selection must be based on the actual operating conditions and project specifications.
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