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Stainless Steel Type 321 and 321H Titanium Stabilized Welding Neck Flange Forged WN Flange

Product Summary
321/321H forged stainless steel WN flanges offer titanium-stabilized resistance to intergranular corrosion at 425–870°C. 321 provides better weldability, while 321H delivers superior high-temperature creep strength for furnace components, heat exchangers, and refinery applications.

Product Details

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Stainless Steel Type 321 Welding Neck Flange

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Stainless Steel Type 321H WN Flange

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Titanium Stabilized Forged Flange

Product Description
321 / 321H Forged Stainless Steel WN Flanges
Stainless Steel Type 321 & 321H are stabilized austenitic stainless steels, very similar to 304 but with titanium added for better resistance to intergranular corrosion at elevated temperatures. The main difference between 321 and 321H is the carbon content.
Chemical Composition
Element Type 321 Stainless Steel (wt%) Type 321H Stainless Steel (wt%)
Carbon (C) ≤ 0.08% 0.04 – 0.10%
Manganese (Mn) ≤ 2.00% ≤ 2.00%
Phosphorus (P) ≤ 0.045% ≤ 0.045%
Sulfur (S) ≤ 0.030% ≤ 0.030%
Silicon (Si) ≤ 0.75% ≤ 0.75%
Chromium (Cr) 17.0 – 19.0% 17.0 – 19.0%
Nickel (Ni) 9.0 – 12.0% 9.0 – 13.0%
Titanium (Ti) ≥ 5 * C content and typically ≤ 0.70% ≥ 5 * C content and typically ≤ 0.70%
Nitrogen (N) ≤ 0.10% ≤ 0.10%
Iron (Fe) Balance (remainder) Balance
Key Differences & Characteristics
  • Stabilization with Titanium
    Titanium is added to tie up carbon as titanium carbides, preventing chromium carbide precipitation at grain boundaries. This gives both 321 and 321H good resistance to intergranular corrosion in the 425–870°C (800–1600°F) range, where 304-type steels can become sensitized.
  • 321 vs 321H Comparison
    Type 321: Lower carbon content (≤ 0.08%), providing better weldability and slightly better resistance to sensitization.
    Type 321H: Higher carbon content (0.04–0.10%), giving higher creep and stress‑rupture strength at elevated temperatures (typically above ~500–600°C), making it preferred for high‑temperature service.
Applications
  • Type 321: Exhaust manifolds, aircraft exhaust systems, thermal oxidizers, and general high‑temperature piping
  • Type 321H: Furnace components, high‑temperature heat exchangers, boiler tubes, and petrochemical/refinery service where long-term high‑temperature strength is needed
For design or certification purposes, always check the exact standard (ASTM/EN/JIS) and product form (plate, pipe, forging), as allowable ranges can vary slightly between specifications and manufacturers.
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