AISI 321H (S32109) Stainless Steel
AISI 321H stainless steel is an austenitic stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. 321H is the AISI designation for this material. S32109 is the UNS number. Additionally, the British Standard (BS) designation is 321S49.
This material is well established: the Further Reading section below cites a number of published standards, and that list is not necessarily exhaustive.
It has a moderately low tensile strength among the wrought austenitic stainless steels in the database.
The graph bars on the material properties cards below compare AISI 321H stainless steel to: wrought austenitic stainless steels (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Brinell Hardness
190
Elastic (Young's, Tensile) Modulus
200 GPa 29 x 106 psi
Elongation at Break
40 %
Fatigue Strength
200 MPa 29 x 103 psi
Poisson's Ratio
0.28
Reduction in Area
51 %
Rockwell B Hardness
82
Shear Modulus
77 GPa 11 x 106 psi
Shear Strength
400 MPa 58 x 103 psi
Tensile Strength: Ultimate (UTS)
580 MPa 85 x 103 psi
Tensile Strength: Yield (Proof)
230 MPa 33 x 103 psi
Thermal Properties
Latent Heat of Fusion
290 J/g
Maximum Temperature: Corrosion
480 °C 890 °F
Maximum Temperature: Mechanical
940 °C 1720 °F
Melting Completion (Liquidus)
1430 °C 2600 °F
Melting Onset (Solidus)
1380 °C 2520 °F
Specific Heat Capacity
480 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
15 W/m-K 8.7 BTU/h-ft-°F
Thermal Expansion
17 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
2.4 % IACS
Electrical Conductivity: Equal Weight (Specific)
2.7 % IACS
Otherwise Unclassified Properties
Base Metal Price
16 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
3.2 kg CO2/kg material
Embodied Energy
46 MJ/kg 20 x 103 BTU/lb
Embodied Water
140 L/kg 17 gal/lb
Common Calculations
PREN (Pitting Resistance)
18
Resilience: Ultimate (Unit Rupture Work)
190 MJ/m3
Resilience: Unit (Modulus of Resilience)
140 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
25 points
Strength to Weight: Axial
21 points
Strength to Weight: Bending
20 points
Thermal Diffusivity
4.0 mm2/s
Thermal Shock Resistance
12 points
Alloy Composition
Among wrought stainless steels, the composition of AISI 321H stainless steel is notable for including titanium (Ti). Titanium is used to broadly improve mechanical properties.
| Fe | 65.4 to 74 | |
| Cr | 17 to 19 | |
| Ni | 9.0 to 12 | |
| Mn | 0 to 2.0 | |
| Si | 0 to 0.75 | |
| Ti | 0 to 0.7 | |
| C | 0.040 to 0.1 | |
| P | 0 to 0.045 | |
| S | 0 to 0.030 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
EN 10095: Heat resisting steels and nickel alloys
ASTM A479: Standard Specification for Stainless Steel Bars and Shapes for Use in Boilers and Other Pressure Vessels
Machining of Stainless Steels and Super Alloys: Traditional and Nontraditional Techniques, Helmi A. Youssef, 2016
ASTM A182: Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service
ASTM A276: Standard Specification for Stainless Steel Bars and Shapes
ASTM A240: Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications
ASTM A959: Standard Guide for Specifying Harmonized Standard Grade Compositions for Wrought Stainless Steels
Corrosion of Austenitic Stainless Steels: Mechanism, Mitigation and Monitoring, H. S. Khatak and B. Raj (editors), 2002
Pressure Vessels: External Pressure Technology, 2nd ed., Carl T. F. Ross, 2011
Austenitic Stainless Steels: Microstructure and Mechanical Properties, P. Marshall, 1984