What is AISI 321 Stainless Steel 2B Finished Strip?
Dec 05, 2025
Leave a message
What is AISI 321 Stainless Steel Strip with a 2B Finish?
AISI 321 2B finished stainless steel strip is a titanium-stabilized austenitic stainless steel precision strip featuring a smooth, non-reflective cold-rolled surface finish. The addition of titanium (at least 5 times the carbon content) prevents chromium carbide precipitation during welding or high-temperature exposure (427°C–816°C / 800°F–1500°F), protecting the metal from intergranular corrosion. The 2B surface finish process-consisting of cold rolling, heat treatment, pickling, and a light skin pass through polished rolls-makes it ideal for precision stamping, expansion joints, and high-temperature thermal shielding applications.
What is a 2B surface finish?
Surface condition directly determines a material's formability, the rate of mold wear, and the requirements for subsequent processing steps. The "2B surface" is the standard rolled finish in the precision stainless steel strip industry.
1. Cold rolling: Precision rolling is performed to achieve exact thickness tolerances.
2. Annealing and pickling: Heat treatment restores ductility, while pickling removes oxide scale.
3. Skin passing (temper rolling): A final light rolling pass using highly polished rolls ensures flatness, a smooth surface texture (Ra 0.1–0.5 µm), and a mild metallic luster.
AISI 321 Chemical Composition
AISI 321 (UNS S32100 / EN 1.4541) is a titanium-stabilized austenitic stainless steel. The addition of titanium binds carbon atoms to form titanium carbides, reducing chromium carbide precipitation during welding and maintaining corrosion resistance along grain boundaries.
| Chemical Element | AISI 321 (wt%) | EN 1.4541 Equivalent (wt%) |
|---|---|---|
| Chromium (Cr) | 17.00–19.00% | 17.00–19.00% |
| Nickel (Ni) | 9.00–12.00% | 9.00–12.00% |
| Titanium (Ti) | 5 × (C + N) ≤ 0.70% | 5 × C ≤ 0.70% |
| Carbon (C) | ≤ 0.08% | ≤ 0.08% |
| Manganese (Mn) | ≤ 2.00% | ≤ 2.00% |
| Silicon (Si) | ≤ 0.75% | ≤ 1.00% |
Key Applications for 321 2B Stainless Steel Strip
Because 321 2B strip combines high-temperature creep strength, immunity to weld decay, and excellent cold-forming properties, it is preferred across high-stress industries:
Automotive & Aerospace: Exhaust flexible joints, expansion bellows, aircraft collector rings, and heat exchangers.
Industrial Thermal Processing: Furnace baffles, flexible metal hoses, burner tubes, and boiler gaskets.
Energy & Chemical: Expansion joints, pressure vessel gaskets, and high-temperature diaphragm valves.
321 vs. 316 vs. 304 Stainless Steel Coils: Key Differences
| Material Property / Criteria | AISI 321 2B Strip | AISI 304 2B Strip | AISI 316L 2B Strip |
|---|---|---|---|
| Maximum Continuous Service Temperature | Up to 816°C (1500°F) | Approximately 425°C (800°F) | Approximately 425°C (800°F) |
| Intergranular Corrosion Risk | Extremely Low - titanium stabilized to prevent chromium carbide precipitation | Higher risk after welding without proper heat treatment | Low - ultra-low carbon content reduces sensitization risk |
| Chloride Pitting Resistance | Moderate | Moderate | High - enhanced by approximately 2.0–3.0% molybdenum addition |
| Primary Advantage | Excellent high-temperature strength, weld decay resistance, and long-term structural stability | Economical general-purpose stainless steel with good formability and corrosion resistance | Superior resistance to chlorides, seawater, and chemical environments |
| Typical Cost Index | Approximately 1.15–1.25 × the price of 304 | Base cost (1.0 ×) | Approximately 1.35–1.50 × the price of 304 |
Sourcing & Quality Control Checklist
When requesting quotes for AISI 321 2B stainless steel strip, verify these technical parameterswith your supplier:
Slitting Edge Quality: Specify Mill Edge or Slit Edge (Deburred) to avoid feed issues inautomated stamping presses.
Temper Condition: Order Soft Annealed (TR) for deep drawing or 1/4 Hard /1/2 Hard forspring/structural applications.
Coil Packaging: Ensure paper-interleaved or PVC film protection to preserve the 2Bsurface quality during transit.
Compliance Certificates: Require Mill Test Certificates (MTC to EN 10204 3.1) confirming
Titanium ratio (Ti> 5 X C) and ASTM A240/A480 compliance.
If you are planning a project, could you share what you plan to use the steel strip for so I can let you know if grade 321 with a 2B finish is the best choice for your needs?
FAQ
Q1: Is AISI 321 stainless steel magnetic?
A: In the fully annealed condition, AISI 321 is completely non-magnetic (austenitic structure). However, like most 300-series grades, it may exhibit slight magnetism after severe cold working or slitting due to partial martensitic transformation.
Q2: Can 304L 2B strip replace 321 for high-temperature applications?
A: At temperatures up to 425°C (800°F), 304L effectively resists intergranular corrosion due to its low carbon content. However, at temperatures exceeding 500°C, the tensile strength and creep-rupture strength of 304L drop rapidly; in contrast, AISI 321 retains its structural strength at temperatures up to 816°C thanks to the presence of dispersed titanium carbides.
Q3: What are the typical thickness and width ranges for 321 2B precision strip?
A: Thickness: 0.05 mm to 3.0 mm (0.002" – 0.118")
Width: 5.0 mm to 600 mm (precision slit widths available upon request)
Send Inquiry