These titanium bearing stainless steels are stabilized against carbide precipitation and designed for eperation within the damaging temperature range where carbide precipitation develops. In this type of steel, the carbon combines preferentially with titanium to form a harmless titanium carbide, leaving the chromium in solution ot maintain full corrosion resistance.
· ASTM:A312, A403, A182
· ASME: SA312, SA403, SA182
Grade | 321 | 321H |
UNS Designation | S210000 | S32109 |
Carbon (C) Max. | 0.08 | 0.04 – 0.10 |
Manganese (Mn) Max. | 2.00 | 2.00 |
Phosphorous (P) Max. | 0.040 | 0.040 |
Sulphur (S) Max. | 0.030 | 0.030 |
Silicon (Si) Max. | 0.75 | 0.75 |
Chromium (Cr) | 17.0 – 20.0 | 17.0 – 20..0 |
Nickel (Ni) | 9.0 – 12.0 | 9.0 – 12.0 |
Molybdenum (Mo) | — | — |
Nitrogen (N) | 0.1 Max. | 0.1 Max. |
Iron (Fe) | Bal. | Bal. |
Other Elements | Ti=5(C) to 0.70% | Ti=5(C) to 0.60% |
*The titanium content shall not be less than 5 times the carbon content and not more than 0.60%. 321H requires the titanium content to be not less than 4 times the carbon content and not more than 0.60%.
Material | Tensile Strength Rm, N/mm² | Yield Strength Rp 0.2, N/mm² | % Elongation |
Alloy 321 Tube | 500-730 | 200 | 35 |
· Immune to intergranular corrosion when heated within the carbide precipitation range.
· Titanium addition eliminates the formation of chromium carbides at the grain boundaries by tying up the carbon and nitrogen as titanium carbides or nitrides.
· Better high temperature properties than 304 or 304L. Generally used for parts which are intermittently heated up to 1500°F. For continuous service the alloy is good to 1650°F.
· May be susceptible to chloride stress cracking.
· Excellent weldability in field.
· Type 321H has high carbon (.04 to .10) for better high temperature creep properties.
· High temperature chemical process heat exchanger tubes
· Refineries
· High temperature steam service
· Tensile Strength (KSI): 75
· Yield Strength (KSI): 30
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