 |
Material: Nickel 200, 201, 20, 31
Type: Plate, Sheet, Strip and Coil
Thickness: 0.3-1200mm, customized
Width: 0-2500mm, customized
Length: 0-12m, customized
Surface: No.1 No.2D No.2B BA No.3 No.4 No.6 No.7, etc
● Nickel 200/201: Commercially pure wrought nickel (Ni ≥99.0%), ASTM B162 sheet/plate; 201 differs from 200 only in carbon content
● Alloy 31: Superaustenitic Fe-Ni-Cr-Mo-N alloy (PREN >50), ASTM B625; fills gap between Alloy 926 and Hastelloy C276
● Alloy 20: Ni-Fe-Cr-Mo-Cu alloy stabilized with Nb, ASTM B463; specifically designed for hot sulfuric acid service
All four grades available as sheet/plate/strip with full EN 10204 3.1 certification
Type | Plate, Sheet, Strip, Coil | |
|---|---|---|
Surface | No.1 No.2D No.2B BA No.3 No.4 No.6 No.7 | |
Size | Width: 0-2500mm / Customized | |
Manufacturing Technique | Hot / Cold Rolled | |
Packing | Steel Frame, waterproof paper, wooden palet, wooden case or as per the dient's requirements | |
Nickel Grades | Alloy 200, 201, 31, 20 | |
Nickel 200/201 — The Alkali Specialist
Nickel 200 is the ONLY standard engineering alloy capable of handling hot, concentrated NaOH across the full concentration-temperature spectrum. While stainless steels suffer stress corrosion cracking (SCC) in caustic environments, Nickel 200 remains immune. For high-temperature caustic service (>315°C), Nickel 201 eliminates graphite embrittlement risk, making it the definitive choice for caustic evaporators and nuclear steam generators.
Alloy 31 — The Cost-Effective PREN Champion
With PREN >50 at a cost ~40% lower than Hastelloy C-276, Alloy 31 delivers unmatched value in severe chloride + acid environments. It is the preferred metallurgical solution for FGD scrubbers where mixed acids (H₂SO₄ + HCl + HF) condense from flue gases — an environment that rapidly destroys 316L and 904L.
Alloy 20 — The Sulfuric Acid Benchmark
Alloy 20 has been the industry standard for H₂SO₄ service for over 70 years. Its unique Cu-Nb combination provides resistance to both general corrosion and intergranular attack in hot sulfuric acid up to 80% concentration — a regime where 316L loses >5 mm/year.
Nickel alloy flat products are manufactured in multiple dimensional classifications. The following table presents the standard product forms available for all four grades.
Product Form | Thickness Range | Width Range | Length Range | Typical Applications |
Sheet | 0.3 – 6.0 mm | 1000 – 2500 mm | 2000 – 12000 mm | Linings, baffles, thin-wall tanks |
Plate | 6.0 – 100 mm+ | 1000 – 4000 mm | 2000 – 12000 mm | Pressure vessels, reactor shells, FGD absorbers |
Strip / Coil | 0.1 – 3.0 mm | 10 – 650 mm | Coil form | Gaskets, springs, stamped parts |
Foil | 0.01 – 0.15 mm | 10 – 300 mm | Coil form | Battery components, electronic shielding |
Nickel alloy sheets are produced through two distinct rolling processes. The choice between hot-rolled and cold-rolled affects mechanical properties, surface quality, dimensional tolerance, and cost.
Parameter | Hot-Rolled (HR) | Cold-Rolled (CR) |
Processing Temperature | Above recrystallization (>900°C) | Room temperature |
Surface Finish | Mill finish (No.1), rough oxide scale | Smooth (No.2B/2D/BA), oxide-free |
Thickness Tolerance | ±0.75 mm (typical) | ±0.05 mm (typical) |
Grain Structure | Coarse, equiaxed after annealing | Fine, elongated (work-hardened) |
Strength | As-annealed (moderate) | Higher (work-hardening effect) |
Best For | Heavy plate, pressure vessels, structural | Precision parts, thin sections, cosmetic applications |
Condition | Process Description | Applicable Grades |
Annealed (A) | Solution-annealed at specified temperature followed by rapid cooling. Softest, most ductile condition. | All four grades |
As-Rolled (AR) | As-rolled from hot or cold mill without subsequent heat treatment. Moderate strength. | All four grades |
Skin-Passed | Light cold-rolling after annealing to improve flatness and surface brightness (No.2B finish). | 200/201, Alloy 20 |
BA (Bright Annealed) | Annealed in protective atmosphere (H₂ or vacuum) to maintain mirror-bright surface. | 200/201 |
Work-Hardened | Cold-worked to increase strength at expense of ductility. Available in 1/4, 1/2, 3/4, and full hard tempers. | 200/201 (spring applications) |
All compositions are weight % maximum unless range specified. Data per ASTM B162 (Nickel 200/201), ASTM B625 (Alloy 31), and ASTM B463 (Alloy 20).
Element (wt%) | Nickel 200 | Nickel 201 | Alloy 31 | Alloy 20 |
Ni | 99.0 min | 99.0 min | 30.0 – 32.0 | 32.0 – 38.0 |
Cr | — | — | 26.0 – 28.0 | 19.0 – 21.0 |
Mo | — | — | 6.0 – 7.0 | 2.0 – 3.0 |
Cu | ≤0.25 | ≤0.25 | 1.0 – 1.4 | 3.0 – 4.0 |
Fe | ≤0.40 | ≤0.40 | Balance | Balance |
C | ≤0.15 | ≤0.02 | ≤0.015 | ≤0.07 |
Mn | ≤0.35 | ≤0.35 | ≤2.0 | ≤2.0 |
Si | ≤0.35 | ≤0.35 | ≤0.3 | ≤1.0 |
S | ≤0.01 | ≤0.01 | — | ≤0.035 |
P | — | — | — | ≤0.045 |
N | — | — | 0.15 – 0.25 | — |
Nb+Ta | — | — | — | 8×C – 1.0 |
Source: ASTM B162-22 (Nickel 200/201); ASTM B625-22 (Alloy 31); ASTM B463-22 (Alloy 20); Special Metals Corporation technical bulletins.
Property | Nickel 200 | Nickel 201 | Alloy 31 | Alloy 20 |
Tensile Strength (MPa) | 380 – 550 | 350 – 500 | ≥650 | ≥620 |
Yield Strength, 0.2% (MPa) | 100 – 300 | 80 – 250 | ≥270 | ≥300 |
Elongation (%) | ≥40 | ≥40 | ≥35 | ≥40 |
Hardness (HRB) | 45 – 70 | 45 – 65 | ≤230 HBW | ≤95 HRB |
Elastic Modulus (GPa) | 207 | 207 | 195 | 193 |
Property | Nickel 200/201 | Alloy 31 | Alloy 20 |
Density (g/cm³) | 8.89 | 8.1 | 8.08 |
Melting Range (°C) | 1435 – 1446 | 1350 – 1400 | 1370 – 1425 |
Thermal Conductivity (W/m·K at 20°C) | 70 – 79 | 11 – 14 | 12 – 15 |
Coeff. of Thermal Expansion (µm/m·°C) | 13.3 (20–100°C) | 14.5 (20–100°C) | 14.7 (20–100°C) |
Electrical Resistivity (µΩ·m at 20°C) | 0.096 | 1.0 – 1.1 | 1.05 |
Curie Temperature (°C) | ~360 (ferromagnetic) | Non-magnetic | Non-magnetic |
The following table rates each grade's performance in key corrosive environments on a 1–5 scale (5 = Excellent / Immune, 1 = Unsuitable). Comparison with 316L provided as baseline.
Corrosive Environment | 316L | Ni 200/ | Alloy 31 | Alloy 20 | Winner |
NaOH (caustic) all conc. | 2 | 5 | 3 | 2 | Ni 200/201 |
H₂SO₄ (10–80%) | 1 | 2 | 4 | 5 | Alloy 20 |
HCl (hydrochloric) dilute | 1 | 1 | 4 | 1 | Alloy 31 |
Seawater / NaCl crevice | 2 | 3 | 5 | 2 | Alloy 31 |
H₃PO₄ (phosphoric acid) | 2 | 2 | 5 | 4 | Alloy 31 |
HNO₃ (nitric acid) | 4 | 1 | 5 | 4 | Alloy 31 |
FGD condensate (H₂SO₄+HCl+HF) | 1 | 1 | 5 | 2 | Alloy 31 |
High-purity water (nuclear grade) | 3 | 5 | 4 | 3 | Ni 201 |
Food / pharmaceutical grade | 4 | 4 | 4 | 5 | Alloy 20 |
● If your primary threat is CAUSTIC (NaOH, KOH) → Select Nickel 200 (≤315°C) or 201 (>315°C).
● If your primary threat is HOT SULFURIC ACID (H₂SO₄) → Select Alloy 20 — 70-year track record.
● If your environment has MIXED ACIDS + CHLORIDES (FGD, phosphoric) → Select Alloy 31 — PREN >50.
● If your environment is OXIDIZING (HNO₃) → Select Alloy 31, NOT Nickel 200.
● If you need HIGH ELECTRICAL CONDUCTIVITY → Select Nickel 200/201 (70 W/m·K).
All sheets are manufactured and tested in accordance with the following primary ASTM/ASME standards. EN and ISO equivalents are provided for cross-reference.
Grade | ASTM Standard | ASME Equivalent | EN Standard | Scope |
Nickel 200/201 | ASTM B162 | ASME SB-162 | EN 1652 (Cu-Ni) | Plate, sheet & strip |
Alloy 31 | ASTM B625 | ASME SB-625 | EN 10028-7 | Plate, sheet & strip |
Alloy 20 | ASTM B463 | ASME SB-463 | EN 10028-7 | Plate, sheet & strip |
Standard | Title / Description | Applicable Grades |
ASTM A480/A480M | General requirements for flat-rolled stainless & heat-resisting steel plate, sheet, strip | Alloy 31, Alloy 20 |
ASTM A262 | Standard practices for detecting susceptibility to intergranular attack | Alloy 20 (Practice C) |
ASTM E112 | Standard test methods for determining average grain size | All four grades |
ASTM G48 | Pitting & crevice corrosion resistance test (FeCl₃) | Alloy 31 (Method C) |
EN 10204 | Metallic products — types of inspection documents | All four grades |
NORSOK M-650 | Qualification of manufacturers of special materials (Norwegian petroleum) | Alloy 31 |
ISO 6208 | Nickel alloy plate, sheet and strip — technical delivery conditions | Nickel 200/201 |
Q1: What is the fundamental difference between Nickel 200 and Nickel 201?
The ONLY compositional difference is carbon content: Nickel 200 allows ≤0.15% C, while Nickel 201 restricts carbon to ≤0.02%. All other elements are identical. The practical consequence: at service temperatures between 315°C and 760°C, Nickel 200 can form intergranular graphite precipitates that cause embrittlement. Nickel 201's ultra-low carbon prevents this. For applications below 315°C, the two grades are functionally interchangeable, and many mills now supply dual-certified 200/201 material.
Q2: Can Alloy 20 replace 316L in sulfuric acid service?
Absolutely — and it is the recommended upgrade path. 316L experiences catastrophic corrosion (>5 mm/year) in hot H₂SO₄ above 20% concentration. Alloy 20's deliberate copper addition (3–4%) and niobium stabilization provide useful resistance up to 80% H₂SO₄ at moderate temperatures. However, for boiling sulfuric acid or concentrations above 90%, higher nickel alloys (e.g., Hastelloy B-2) are required.
Q3: Why is Alloy 31 considered a 'cost-effective' alternative to Hastelloy C-276?
Alloy 31's nickel content (30–32%) is approximately half that of C-276 (Ni ~57%), making its raw material cost ~40–50% lower. Despite this, its PREN exceeds 50 — approaching C-276 territory (PREN ≈64–70). In FGD and phosphoric acid environments, Alloy 31 delivers equivalent service life at substantially lower installed cost. The key limitation: C-276 remains superior in HCl above 5% concentration and at temperatures exceeding 120°C in severe chloride environments.
Q4: Is Nickel 200/201 magnetic?
Yes — Nickel 200 and 201 are ferromagnetic at room temperature, with a Curie temperature of approximately 360°C. Above this temperature, they become paramagnetic. Alloy 31 and Alloy 20 are non-magnetic (austenitic structure) at all temperatures. This magnetic property of Nickel 200/201 must be considered in applications involving electromagnetic compatibility (EMC) or magnetic field-sensitive equipment.
Q5: What surface finish is required for pharmaceutical GMP applications?
For GMP-compliant pharmaceutical equipment, the minimum standard is ASTM No.2B with Ra ≤0.5 µm. For sterile processing and Water-for-Injection (WFI) systems, electropolished finish (Ra ≤0.25 µm) is recommended to eliminate micro-crevices where biofilms can anchor. Alloy 20 is the preferred grade for pharmaceutical acid processing, while Nickel 200 is used for pure caustic cleaning media.
Q6: Can these alloys be welded, and what filler metals are recommended?
All four grades are readily weldable using GTAW, GMAW, and SMAW processes. Recommended filler metals: Nickel 200/201 → ERNi-1 (AWS A5.14); Alloy 31 → ERNiCrMo-13 (Alloy 59 filler); Alloy 20 → ER320LR (UNS N08022). For Alloy 20, post-weld heat treatment is generally NOT required due to its niobium stabilization — a significant fabrication advantage over unstabilized austenitics. Always ensure proper interpass temperature control (<150°C for Alloy 31) and full penetration with inert gas purging on the root side for corrosion service.
