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Alloy 20 Round Bar - ASTM B473 UNS N08020 Supplier
Nicorex Alloys is an ISO 9001 and ISO 14001 certified supplier and stockist based in Mumbai, India. We supply ASTM B473 UNS N08020 bar with EN 10204 3.1 mill test certificates on every heat and NACE MR0175 compliant inventory.
Alloy 20 round bar is a low-carbon, niobium-stabilised (Nb+Ta ≤1.0%) austenitic nickel-iron-chromium alloy with copper and molybdenum additions. UNS N08020 (W.Nr. 2.4660) resists dilute sulphuric acid across the full 0-100% concentration range at temperatures up to 35°C. The composition combines 32-38% nickel (prevents chloride SCC), 19-21% chromium (oxidation and nitric acid resistance), 3-4% copper (sulphuric acid immunity), 2-3% molybdenum (pitting/crevice resistance), and niobium stabilisation that prevents sensitisation in the heat-affected zone. This means Carpenter 20Cb-3 bar can be welded and used in the as-welded condition without PWHT in most applications. A major cost and schedule advantage. Mechanical properties per ASTM B473 include a minimum 551 MPa (80 ksi) tensile, 241 MPa (35 ksi) yield, 30% elongation, and 217 HBW max hardness. Typically these values could be 90 ksi (620 MPa) tensile, 45 ksi (310 MPa) yield, and 40% elongation.
Hot-finished and cold-finished bar is available in diameters from 6 mm to 350 mm, round, hex, flat, and square forms, in lengths of 1000-6000 mm. Alloy 20 density is 8.08 g/cm³ (0.292 lb/in³). Maximum service temperature per ASME reaches 538°C (1000°F). Governing specifications include ASTM B473 / ASME SB473. Industries served include chemical processing, pharmaceutical, oil and gas, power generation, marine, and pulp and paper. Also known as Incoloy 20, Nickelvac 20, and Nicrofer 3620 Nb.
Alloy 20 Bar & Rod Specifications
| Standard | ASTM B473 / ASME SB473 |
|---|---|
| Forms | Round, Hex, Flat, Square Bar |
| Diameter | 6.35 mm+ (hot-finished); 12.7 mm+ (cold-finished) |
| Length | 1000 – 6000 mm, custom cut |
| Condition | Annealed / Solution Annealed / Stabilise-Annealed |
| Finish | Black, Bright Polished, Rough Turned, Centreless Ground |
Chemical Composition of Alloy 20 Round Bar
| Element | Nickel (Ni) | Chromium (Cr) | Cobalt (Co) | Titanium (Ti) | Aluminium (Al) | Carbon (C) | Iron (Fe) | Manganese (Mn) | Silicon (Si) | Copper (Cu) | Boron (B) | Zirconium (Zr) | Sulphur (S) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Composition | Balance (≥53%) | 18.0 – 21.0 | 15.0 – 21.0 | 1.8 – 3.0 | 1.0 – 2.0 | 0.13 max | 3.0 max | 1.0 max | 1.0 max | 0.2 max | 0.02 max | 0.15 max | 0.015 max |
Mechanical Properties of ASTM B473 Alloy 20 Bar
| Property | Tensile Strength | Yield Strength 0.2% | Elongation (2 in.) | Hardness |
|---|---|---|---|---|
| ASTM B473 Min | 551 MPa (80 ksi) | 241 MPa (35 ksi) | 30% | 217 HBW / B95 max |
| Typical | 620 MPa (90 ksi) | 310 MPa (45 ksi) | 40% | B83 typical |
At 50% cold reduction, yield climbs from 306 MPa to 962 MPa and tensile reaches 1,017 MPa, approaching precipitation-hardened nickel alloy strength while retaining sulphuric acid resistance.
Nickel Alloy 20 Round Bar Equivalent Grades
| Standard / System | UNS | Werkstoff Nr. | EN | AFNOR |
|---|---|---|---|---|
| Designation | N08020 | 2.4660 | NiCr20CuMo | Z2NCUD31-20AZ |
Physical Properties of Alloy 20 Bar & Rod
| Property | Density | Melting Range | Elastic Modulus | Thermal Expansion (25-100°C) | Thermal Conductivity | Electrical Resistivity | Specific Heat |
|---|---|---|---|---|---|---|---|
| Value | 8.08 | 1385−1443 | 193 | 14.7 × 10⁻⁶ | 12.3 | 1.08 | 460 |
| Unit | g/cm³ | °C | GPa | /°C | W/m·K | µΩ·m | J/kg·K |
Get Alloy 20 Bars at Competitive Prices
Available Forms of Alloy 20 Bar & Rod
Alloy 20 Round Bar
Alloy 20 Hex Bar
Incoloy 20 Flat Bar
Alloy 20 Square Bar
Alloy 20 Forged Bar
Alloy 20 Rectangular Bar
Alloy 20 Hollow Bar
Nickel Alloy Rod
Sulphuric Acid Performance of Alloy 20 Bar
Alloy 20 bar resists sulphuric acid across the full 0-100% concentration range at temperatures up to 35°C. The 3-4% copper content drives reducing-acid immunity that 316L and 317L cannot match. At 33% nickel, UNS N08020 has practical immunity to chloride stress corrosion cracking.
Intergranular corrosion testing per ASTM A262 (Practice B or E) is available as supplementary requirement S1 under ASTM B473. The niobium stabilisation inherently minimises sensitisation, but purchasers should specify this test for critical acid-handling equipment. ASME maximum service temperature: 538°C (1000°F).
Hot Working, Machining & Heat Treatment of Alloy 20 Bar
Hot form at 760-1175°C. Finish forging before the stock drops below 980°C. Stabilise-anneal at 982-1010°C for time proportional to section thickness, then air cool. This precipitates niobium carbides preferentially over chromium carbides.
Weld with all common arc processes except oxyacetylene: GTAW, GMAW, SMAW, and plasma. Niobium stabilisation minimises carbide precipitation in the HAZ. Machine in the annealed condition using rigid setups, positive rake carbide inserts, and constant feed to stay below the work-hardened layer.
Industries and Applications of Alloy 20 Round Bar
- Sulphuric acid reactor internals, agitator shafts, mixing tank components, and pickling equipment hardware.
- Acid handling valve stems, sterile tank hardware, and dye manufacturing equipment.
- Sour-gas valve components per NACE MR0175, crude distillation column internals, and HF alkylation unit hardware.
- Flue gas desulphurisation scrubber components and wet scrubber pump shafts.
- Seawater pump shafts and mechanical seal components. 33% Ni provides chloride SCC immunity.
- Bleach plant shafts and chemical recovery boiler hardware.
How to Order Alloy 20 Round Bar & Rod from Nicorex Alloys
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Product Form - Round, Hex, Flat, Square, Forged Bar
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Specification - ASTM B473 / ASME SB473
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Grade - UNS N08020
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Diameter, Tolerance, and Length - Diameter, tolerance (H9-H12), and length
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Condition - Annealed / Stabilise-Annealed / Strain-Hardened
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Surface Finish and Quantity - Surface finish and quantity
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Testing - IGC per ASTM A262 if required
- Documentation - EN 10204 3.1 MTC, NACE certificate
Frequently Asked Questions
What is the Difference between Hot-Finished and Cold-Finished Alloy 20 Bar?
Why is Alloy 20 Preferred Over 316L for Sulphuric Acid Service?
Does Alloy 20 Bar Require Intergranular Corrosion Testing?
What is the Maximum Service Temperature for Alloy 20 Bar?
What Machining Precautions Apply to Alloy 20 Round Bar?
Can Alloy 20 Bar be Cold Worked to Higher Strength?
Yes. At 50% cold reduction, yield rises from 306 to 962 MPa and tensile from 661 to 1,017 MPa (Rockwell C30). Elongation drops to 4%, but corrosion resistance is retained.