321/321H Stainless Steel Plate – High-Temperature & Oxidation Resistance
Sandmeyer Steel Company stocks Alloy 321 stainless steel plate in thicknesses from 3/16″ through 4″. A high carbon version, Alloy 321H (UNS S32109) stainless steel plate, can also be ordered in the same thickness range.
Available thicknesses for Alloy 321/321H:
| 3/16" | 1/4" | 5/16" | 3/8" | 1/2" | 5/8" | 3/4" | 7/8" | 1" | 1 1/8" |
| 4.8mm | 6.3mm | 7.9mm | 9.5mm | 12.7mm | 15.9mm | 19mm | 22.2mm | 25.4mm | 28.6mm |
| 1 1/4" | 1 1/2" | 1 3/4" | 2" | 2 1/4" | 2 1/2" | 2 3/4" | 3" | 3 1/2" | 4" |
| 31.8mm | 38.1mm | 44.5mm | 50.8mm | 57.2mm | 63.5mm | 69.9mm | 76.2mm | 88.9mm | 101.6mm |
Alloy 321 (UNS S32100) is stabilized stainless steel plate which offers as its main advantage an excellent resistance to intergranular corrosion following exposure to temperatures in the chromium carbide precipitation range from 800 to 1500°F (427 to 816°C). Alloy 321 stainless steel plate is stabilized against chromium carbide formation by the addition of titanium.
Alloy 321 stainless steel plate is also advantageous for high temperature service because of its good mechanical properties. Alloy 321 stainless steel plate offers higher creep and stress rupture properties than Alloy 304 and, particularly, Alloy 304L, which might also be considered for exposures where sensitization and intergranular corrosion are concerns.
Specification Sheet Overview
for Alloy 321/321H (UNS S32100, S32109, S32109)
W. Nr. 1.4541:
General Properties
Alloy 321 (UNS S32100) is titanium stabilized austenitic stainless steel plate 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) stainless steel plate 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 certification.
Alloy 321 stainless steel plate cannot be hardened by heat treatment, only by cold working. It can be easily welded and processed by standard shop fabrication practices.
Corrosion Resistance
Alloy 321 stainless steel plate exhibits good general corrosion resistance that is comparable to 304. It was developed for use in the chromium carbide precipitation range of 1800 – 1500°F (427 – 816°C) where un-stabilized alloys such as 304 are subject to intergranular attack.
The alloy can be used in most diluted organic acids at moderate temperatures and in pure phosphoric acid at lower temperatures and up to 10% diluted solutions at elevated temperatures. Alloy 321 resists polythionic acid stress corrosion cracking in hydrocarbon service. It can also be utilized in chloride or fluoride free caustic solutions at moderate temperatures.
Alloy 321 stainless steel plate does not perform well in chloride solutions, even in small concentrations, or in sulfuric acid service.
Chemical Analysis
Weight % (all values are maximum unless a range is otherwise indicated)
| Element | 321 | 321H |
|---|---|---|
| Chromium | 17.00 min.-19.00 max. | 17.00 min.-19.00 max. |
| Nickel | 9.00 min.-12.00 max. | 9.00 min.-12.00 max. |
| Carbon | 0.08 | 0.04 min.-0.14 max. |
| Manganese | 2.00 | 2.00 |
| Phosphorus | 0.045 | 0.045 |
| Sulfur | 0.03 | 0.03 |
| Silicon | 0.75 | 0.75 |
| Titanium | 5 x (C + N) min.-0.70 max. | 4 x (C + N) min.-0.70 max. |
| Nitrogen | 0.10 | 0.10 |
| Iron | Balance | Balance |
Density
0.286 lbs/in3
7.920 g/cm3
Specific Heat
0.12 BTU/lb-°F (32 – 212°F)
444 J/kg-°K (0 – 100°C)
Modulus of Elasticity
28.0 x 106 psi
193 GPa
Thermal Conductivity 200°F (100°C)
9.3 BTU/hr/ft2/ft/°F
16.0 W/m-°K
Melting Range
2550 – 2635°F
1398 – 1446°C
Electrical Resistivity
72 Microhm-cm at 20°F
Mean Coefficient of Thermal Expansion
| Temperature Range | |||
|---|---|---|---|
| °F | °C | in/in °F | cm/cm °C |
| 68-212 | 20-100 | 9.2 x 10-6 | 16.0 x 10-6 |
| 68-1112 | 20-600 | 10.5 x 10-6 | 18.9 x 10-6 |
| 68-1832 | 20-1000 | 11.4 x 10-6 | 20.5 x 10-6 |
Mechanical Properties
Typical Values at 68°F (20°C)
0.2% Offset | Strength | in 2 in. | |||
|---|---|---|---|---|---|
| psi (min.) | (MPa) | psi (min.) | (MPa) | % (min.) | (max.) |
| 30,000 | 205 | 75,000 | 515 | 40 | 217 Brinell |
Fabrication Data
Alloy 321 stainless steel plate can be easily welded and processed by standard shop fabrication practices.
Cold Forming
The alloy is quite ductile and forms easily.
Hot Forming
Alloy not suitable for work at temperatures below 1700°F (927°C). This material must be water quenched, or fully annealed, after working to reattain maximum corrosion resistance.
Machining
The cold work hardening rate of 321 stainless steel plate makes it less machinable than 410 stainless steel, but similar to 304. The table below provides relevant machining data.
| Operation | Tool | Lubrication | ||||||
|---|---|---|---|---|---|---|---|---|
| Depth-mm | Depth-in | Feed-mm/t | Feed-in/t | Speed-m/min | Speed-ft/min | |||
| Turning | High Speed Steel | Cutting Oil | 6 | .23 | 0.5 | .019 | 12-16 | 39-52 |
| Turning | High Speed Steel | Cutting Oil | 3 | .11 | 0.4 | .016 | 18-23 | 59-75 |
| Turning | High Speed Steel | Cutting Oil | 1 | .04 | 0.2 | .008 | 23-28 | 75-92 |
| Turning | Carbide | Dry or Cutting Oil | 6 | .23 | 0.5 | .019 | 67-76 | 220-249 |
| Turning | Carbide | Dry or Cutting Oil | 3 | .11 | 0.4 | .016 | 81-90 | 226-295 |
| Turning | Carbide | Dry or Cutting Oil | 1 | .04 | 0.2 | .008 | 99-108 | 325-354 |
| Depth of cut-mm | Depth of cut-in | Feed-mm/t | Feed-in/t | Speed-m/min | Speed-ft/min | |||
| Cutting | High Speed Steel | Cutting Oil | 1.5 | .06 | 0.03-0.05 | .0012-.0020 | 16-21 | 52-69 |
| Cutting | High Speed Steel | Cutting Oil | 3 | .11 | 0.04-0.06 | .0016-.0024 | 17-22 | 56-72 |
| Cutting | High Speed Steel | Cutting Oil | 6 | .23 | 0.05-0.07 | .0020-.0027 | 18-23 | 59-75 |
| Drill ø mm | Drill ø in | Feed-mm/t | Feed-in/t | Speed-m/min | Speed-ft/min | |||
| Drilling | High Speed Steel | Cutting Oil | 1.5 | .06 | 0.02-0.03 | .0007-.0012 | 9-13 | 29-42 |
| Drilling | High Speed Steel | Cutting Oil | 3 | .11 | 0.05-0.06 | .0020-.0024 | 11-15 | 36-49 |
| Drilling | High Speed Steel | Cutting Oil | 6 | .23 | 0.08-0.09 | .0031-.0035 | 11-15 | 36-49 |
| Drilling | High Speed Steel | Cutting Oil | 12 | .48 | 0.09-0.10 | .0035-.0039 | 11-15 | 36-49 |
| Feed-mm/t | Feed-in/t | Speed-m/min | Speed-ft/min | |||||
| Milling Profiling | High Speed Steel | Cutting Oil | 0.05-0.10 | .002-.004 | 11-21 | 36-69 | ||
Welding
Alloy 321 stainless steel plate can be readily welded by most standard processes. A post weld heat treatment is not necessary.
Alloy 321/321H Stainless Steel – Frequently Asked Questions
1. What is Alloy 321/321H stainless steel?
Alloy 321 (UNS S32109) is a titanium-stabilized austenitic stainless steel designed to resist intergranular corrosion in the chromium carbide precipitation range of 800–1500°F (427–816°C). Alloy 321H is the higher carbon version of 321, offering improved high-temperature strength and creep resistance.
2. What are common applications for Alloy 321/321H?
Typical applications include:
• Aerospace engine manifolds
• Expansion joints
• Chemical processing equipment
• Food and beverage processing
• Petroleum refining and polythionic acid service
• Thermal oxidizers and waste treatment
• Pharmaceutical manufacturing equipment
3. How does Alloy 321/321H perform in corrosive environments?
It offers general corrosion resistance similar to 304 stainless steel but with superior resistance to intergranular corrosion after thermal exposure. It resists diluted organic acids, pure phosphoric acid (cold and up to 10% hot), and polythionic acid stress corrosion cracking. It is not recommended for use in chloride-rich or sulfuric acid environments.
4. Can Alloy 321/321H be welded?
Yes. It can be readily welded using standard methods without post-weld heat treatment. For best corrosion resistance, proper cleaning of the weld area is advised. Matching or over-alloyed filler materials are recommended.
5. What are the mechanical properties of Alloy 321/321H stainless steel?
Typical values at 68°F (20°C):
• Yield Strength (0.2% offset): 30,000 psi (205 MPa)
• Ultimate Tensile Strength: 75,000 psi (515 MPa)
• Elongation in 2″: 40% (minimum)
• Hardness: 217 Brinell (maximum)
6. What are the physical properties of Alloy 321/321H?
• Density: 0.286 lbs/in³ (7.92 g/cm³)
• Specific Heat: 0.12 BTU/lb°F (32 – 212°F) 444 J/kg-°K (0 – 100°C)
• Modulus of Elasticity: 28.0 × 10⁶ psi (193 GPa)
• Thermal Conductivity at 200°F: 9.3 BTU/hr/ft²/ft/°F (16.0 W/m-K)
• Electrical Resistivity: 72Mmicrohm-cm 20°F
7. Is Alloy 321/321H magnetic?
No. It is non-magnetic in the annealed condition but may become slightly magnetic after significant cold working.
8. What standards apply to Alloy 321/321H stainless steel?
• ASTM A 240
• ASME SA 240
• AMS 5513
• QQ-S 766
9. What are the available thicknesses for Alloy 321/321H plate at Sandmeyer Steel?
Sandmeyer Steel stocks Alloy 321/321H stainless steel plate in thicknesses from 3/16″ (4.8 mm) through 4″ (101.6 mm).