AISI 321 Stainless Steel pipe Properties
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AISI 321 Stainless Steel (SS321), 321H, TP321
AISI 321 stainless steel (SS321) is a titanium-stabilized version of 304 stainless steel. The addition of titanium (Ti) enhances the alloy's stability by preventing chromium carbide precipitation during exposure to temperatures in the sensitization range, such as those encountered during welding. This improves resistance to intergranular corrosion.
For applications requiring superior performance at elevated temperatures, Grade 321H provides enhanced creep strength and stress rupture resistance.
TP321 stainless steel is widely used for seamless, welded, and heavily cold-worked tubing in high-temperature and corrosion-sensitive environments.
Grade 321 Stainless Steel Datasheet Download
What is the equivalent casting grade of stainless steel 321 pipe?
| AISI 321 stainless steel equivalent material | |||||||||
| US | European Union | ISO | Japan | China | |||||
| Standard | AISI Type (UNS) | Standard | Grade (Steel Number) | Standard | ISO Name (ISO Number) | Standard | Grade | Standard | Grade |
| AISI SAE; ASTM A240/A240M; ASTM A276A/276M; ASTM A959 |
321 (UNS S32100) | EN 10088-2; EN 10088-3 | X6CrNiTi18-10 (1.4541) | ISO 15510 | X6CrNiTi18-10 (4541-321-00-I ) | JIS G4321; JIS G4304; JIS G4305; JIS G4309; |
SUS321 | GB/T 1220; GB/T 3280 |
0Cr18Ni10Ti; 06Cr18Ni11Ti (new designation) (S32168) |
| 321H (UNS S32109) | X7CrNiTi18-10 (1.4940) | X7CrNiTi18-10 (4940-321-09-I ) | SUS321H | 1Cr18Ni11Ti; 07Cr19Ni11Ti (new designation) (S32169) |
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| ASTM A312/A312M | TP321 | EN 10216-5; EN 10217-7; | X6CrNiTi18-10 (1.4541) | ISO 9329-4 | X6CrNiTi18-10 | JIS G3459; JIS G3463 |
SUS321TP | GB/T 14975; GB/T 14976 |
0Cr18Ni10Ti; 06Cr18Ni11Ti (new designation) (S32168) |
AISI 321 Stainless Steel round pipe Chemical Composition
| Chemical Composition, % | |||||||||||
| ASTM Type | AISI Type (UNS) | C, ≤ | Si, ≤ | Mn, ≤ | P, ≤ | S, ≤ | Cr | Ni | N, ≤ | Other Elements | Notes |
| ASTM A240/A240M | 321 (UNS S32100) | 0.08 | 0.75 | 2.00 | 0.045 | 0.03 | 17.0-19.0 | 9.0-12.0 | 0.10 | ≥ Ti 5×(C+N), ≤ 0.70 | Plate, Sheet, and Strip for Pressure Vessels |
| ASTM A276A/276M | 1.00 | – | Stainless Steel Bars and Shapes | ||||||||
| ASTM A580/A580M | – | ≥ Ti 5×C | Stainless Steel Wire | ||||||||
| ASTM A240/A240M | 321H (UNS S32109) | 0.04-0.10 | 0.75 | 2.00 | 0.045 | 0.03 | 17.0-19.0 | 9.0-12.0 | 0.10 | ≥ Ti 4x(C+N), ≤ 0.70 | Plate, Sheet, and Strip |
| ASTM A959 | 1.00 | 0.10 | Wrought Stainless Steels | ||||||||
| ASTM A312/A312M | TP321 (UNS S32100) | 0.08 | 1.00 | 2.00 | 0.045 | 0.03 | 17.0-19.0 | 9.0-12.0 | 0.10 | ≥ Ti 5×(C+N), ≤ 0.70 | Stainless Steel Pipes |
| TP321H (UNS S32109) | 0.04-0.10 | 1.00 | 2.00 | 0.045 | 0.03 | 17.0-19.0 | 9.0-12.0 | 0.10 | ≥ Ti 4x(C+N), ≤ 0.70 | ||
EN 1.4541 stainless steel tube Physical Properties
| SS321 Physical Properties | |
| Density, g/cm3 (lb/in.3) | 7.9 (0.29) |
| Melting point, °C (°F) | 1400-1425 (2550-2600) |
| Specific heat capacity, J/kg·K (Btu/lb ·°F) | 500 (0.12) at 20 °C |
| Electrical resistivity, μΩ·m | 0.72 at 20 °C |
| Magnetic permeability | 1.02 (Approximate) |
| Elastic modulus, GPa (106 psi) | 193 (28) |
| Thermal conductivity, W/m·K (Btu/ft · h ·°F) | 16.1 (9.3) at 100 °C (212 °F) |
| 22.2 (12.8) at 500 °C (932 °F) | |
| Coefficient of thermal expansion, 10-6/K (μin./in. ·°F) | 16.6 (9.2) at 0-100 °C (32-212 °F) |
| 17.2 (9.6) at 0-315 °C (32-600 °F) | |
| 18.6 (10.3) at 0-538 °C (32-1000 °F) | |
SS 321 Mechanical Properties
| ASTM A312 321 stainless steel pipe mechanical properties | ||||
| ASTM | AISI Type (UNS) | Thickness (t), in. (mm) | Tensile Strength, MPa (ksi), ≥ | 0.2% Yield Strength, MPa (ksi), ≥ |
| ASTM A312/A312M | TP321, TP321H | Welded | 515 (75) | 205 (30) |
| Seamless: t ≤ 0.375 (9.50) | ||||
| Seamless: t > 0.375 in. (9.50) | 485 (70) | 170 (25) | ||
| ASTM | AISI Type (UNS) | Conditions | Tensile Strength, MPa (ksi), ≥ | 0.2% Yield Strength, MPa (ksi), ≥ | Elongation in 50 mm (2 in.), %, ≥ | Reduction of Area, %, ≥ | Brinell Hardness (HBW), ≤ | Rockwell Hardness (HRBW), ≤ | Product forms |
| ASTM A276/A276M | 321 (UNS S32100) | Annealed, Hot finished | 515 (75) | 205 (30) | 40 | 50 | – | – | Bars and Shapes |
| Annealed, Cold finished, Dia ≤ 12.7 mm (0.5 in.) | 620 (90) | 310 (45) | 30 | 40 | – | – | |||
| Annealed, Cold finished, Dia > 12.7 mm (0.5 in.) | 515 (75) | 205 (30) | 30 | 40 | – | – | |||
| ASTM A580/A580M | Annealed | 520 (75) | 210 (30) | 35 | 50 | Wire | |||
| Cold finished | 620 (90) | 310 (45) | 30 | 40 | – | – | |||
| ASTM A473/A473M | Annealed, Sections ≤ 5 in. (127 mm) | 515 (75) | 205 (30) | 40 | 50 | – | – | Forgings | |
| Annealed, Sections > 5 in. (127 mm) | 70 (485) | ||||||||
| ASTM A240/A240M | 321, 321H (UNS S32109) | – | 515 (75) | 205 (30) | 40 | – | 201 | 92 | Plate, Sheet, and Strip |
High-temperature 321 SS pipe Heat Treatment
Recommended annealing temperature for TP321 and 321 wrought stainless steel: 1040 °C (1900 °F); Minimum 1095 °C (2000 °F) for cold-worked 321H and 1050 °C (1095 °F) for hot-finished 321H
Stress-relieving treatments
For dimensional stability: Stress relieve at 205 to 480 °C (400 to 900 °F) and then slow cool (usual time, 4 h per inch of section).
Stress relief after severe forming: Anneal at 1065 to 1120 °C (1950 to 2050 °F) and then slow cool. Or Anneal at 1065 to 1120 °C (1950 to 2050 °F) and then quench or cool rapidly.
For removing peak stresses only: Stress relieve at below 480 °C (900 °F) and then slow cool.
Typical forging temperature: 925-1260 °C (1700-2300 °F).
SS321 VS. TP321 stainlesss steel pipe ：Weldability
SS321 and TP321 has excellent weldability, no preheating is required. The filling material needs to have similar composition but higher alloy content. Liquation cracking in heat affected zone: low energy input. Fine grain size. Ferrite ≥ 5%.
Recommended filler metals are SS 321, 347, and 348. Electrode is E347 or E308L [service temperature < 370 °C (700 °F)].
321 stainless pipe for boiler applications
Type 321, 321H and TP321 can be used in places where solution treatment after welding is not possible, such as steam lines and superheater pipes and exhaust systems in reciprocating engines and gas turbines with temperatures ranging from 425 to 870 °C (800 to 1600 °F). And fuel injection lines and hydraulic systems for aircraft and aerospace vehicles.
AISI 321 stainless steel pipe supplier-GNEE
Gnee Stainless Steel stocks and supplies the following 321 stainless steel products:
AISI 321 Seamless Pipes:
Outer Diameter: 4 – 219 mm
Wall Thickness: 0.5 – 20 mm
AISI 321 Welded Pipes:
Outer Diameter: 5.0 – 1219.2 mm
Wall Thickness: 0.5 – 20 mm
AISI 321 Plates and Sheets:
Thickness: 0.1 – 100 mm
Width: 10 – 2500 mm
We also work closely with qualified mills to supply SS321H products, which meet or exceed major international standards, including ASTM, ASME, SAE, AMS, ISO, DIN, EN, and BS.
Feel free to contact us anytime at info@gneestainless.com for a quotation or more product information.
