Alloy 321 (UNS S32100) is a titanium stabilized austenitic
stainless steel with good general corrosion resistance. It has
excellent resistance to intergranular corrosion after exposure to
temperatures in the chromium carbide precipitation range of 800 –
1500°F (427 – 816°C). The alloy resists oxidation to 1500°F (816°C)
and has higher creep and stress rupture properties than alloys 304
and 304L. It also possesses good low temperature toughness.
Alloy 321H (UNS S 32109) is the higher carbon (0.04 – 0.10) version
of the alloy. It was developed for enhanced creep resistance and
for higher strength at temperatures above 1000oF (537°C). In most
instances, the carbon content of the plate enables dual
Alloy 321 cannot be hardened by heat treatment, only by cold
working. It can be easily welded and processed by standard shop
ASTM/ASTE: UNS S32100/UNS S 32109
|Yield Strength 0.2%|
Offset ksi (min.)
50 mm (min.)
Thermal Expansion (min/in)-°F
|Thermal Conductivity BTU/hr-ft-°F||Specific Heat BTU/lbm -°F||Modules of Elasticity (annealed)2-psi|
|at 68 °F||at 68 – 212°F||at 68 – 1832°F||at 200°F||at 32 – 212°F||in tension (E)|
|0.286||9.2||20.5||9.3||0.12||28 x 106|
1, Eibits good general corrosion resistance that is comparable to
2, eveloped for use in the chromium carbide precipitation range of
1800 – 1500°F (427 – 816°C) .
3, an be used in most diluted organic acids at moderate
4, an be used in pure phosphoric acid at lower temperatures.
5, an be used in up to 10% diluted solutions at elevated
6, esists polythionic acid stress corrosion cracking in hydrocarbon
7, utilized in chloride or fluoride free caustic solutions at
8, does not perform well in chloride solutions, even in small
concentrations, or in sulfuric acid service.
321/H can be easily welded and processed by standard shop
1, Working temperatures of 2100 – 2300°F (1149 – 1260°C) are
recommended for forging, upsetting and other hot working processes.
2, Alloy not suitable for work at temperatures below 1700°F
3, Material must be water quenched or fully annealed after working
to re-attain maximum corrosion resistance.
1, Quite ductile and forms easily.
1, Readily welded by most standard processes.
2, Post weld heat treatment is not necessary
Hardening rate of 321 makes it less machinable than 410 stainless
steel, but similar to 304