Grade 321
Austenitic stainless · AISI 321 / SAE 30321, UNS S32100, EN 1.4541
Type 321 Titanium-Stabilized Heat-Resistant Stainless, austenitic stainless steel.
Data sheet
| Designations | AISI 321 / SAE 30321 · UNS S32100 · EN 1.4541 (X6CrNiTi18-10) |
|---|---|
| Standards | ASTM A240, ASTM A276, EN 10088-2, AMS 5510 |
Metallurgy
Reference data for Type 321 Titanium-Stabilized Heat-Resistant Stainless, against ASTM A240, ASTM A276, EN 10088-2, AMS 5510.
Elemental composition
X6CrNiTi18-10 to 1.4541
- Chromium 18,00%17,00–19,00%
- Nickel 10,50%9,00–12,00%
- Nitrogen 0,050%max 0,10%
- Carbon 0,040%max 0,080%
- Other additions 1,99%Ti, Mn, Si, P, S
- Iron 69,42%Balance
Proportions use the normalised midpoint of each specified range. The midpoint is a derived figure, not something the standard states: read the table for what is actually specified.
Performance profile
Comparative scores out of ten, for weighing one grade against another
These are relative ratings, not measured properties, and they carry no units. Use them to narrow a shortlist, then work from the specified values.
Composition as specified
| Element | Specified | Nominal |
|---|---|---|
| Iron Fe | Balance | 69,42% |
| Carbon C | max 0,080%cap | 0,040% |
| Chromium Cr | 17,00–19,00% | 18,00% |
| Nickel Ni | 9,00–12,00% | 10,50% |
| Titanium Ti | 0,20–0,70% | 0,45% |
| Manganese Mn | max 2,00%cap | 1,00% |
| Silicon Si | max 0,75%cap | 0,50% |
| Nitrogen N | max 0,10%cap | 0,050% |
| Phosphorus P | max 0,045%cap | 0,025% |
| Sulphur S | max 0,030%cap | 0,015% |
A cap is a ceiling, not a quantity: a heat may contain far less. The nominal column is the midpoint of each range, used for the chart's proportions only.
Mechanical and physical properties
| Property | Value |
|---|---|
| Tensile strength, ultimate | 515 MPa74,7 ksi |
| Yield strength, 0,2% offset | 205 MPa29,7 ksi |
| Elongation at break | 40% |
| Hardness | 170 HBW / 88 HRB |
| Modulus of elasticity | 193 GPa28 Mpsi |
| Density | 7,92 g/cm³0,29 lb/in³ |
| Thermal conductivity | 16,1 W/(m·K)111,7 BTU·in/(hr·ft²·°F) |
| Thermal expansion | 16,6 µm/(m·K)9,2 µin/(in·°F) |
Test condition not yet confirmed. These figures are typical values for the grade; the condition a bar was supplied in changes them materially, so ask us for the mill certificate before designing to a number.
Pitting resistance
PREN 18,8
Cr + 3,3 Mo + 16 N, across the full specified composition
- Freshwater0–20
- Brackish20–32
- Seawater32–40
- Extreme offshoreover 40
A standard states its elements as ranges, so a grade has a window rather than a single score. The bar is that window; the tick is the midpoint.
Corrosion and fabrication
Chloride and marine service
Moderate chloride resistance similar to 304; lacks molybdenum.
Acidic and chemical media
Good in oxidizing environments; titanium addition stabilizes against polythionic acid stress corrosion cracking.
Sensitisation and thermal behaviour
Excellent resistance up to 900°C due to Ti binding carbon as TiC instead of Cr23C6.
Welding
Readily welded with AWS ER321 or ER347 filler metals.
Machining and cold forming
Machinability index 42% relative to AISI 1212. Very Good; comparable to 304, though titanium carbonitride inclusions cause abrasive tool wear.
Where it is used
- Aircraft exhaust manifolds, collector rings, and jet engine casings
- Expansion joints and metal bellows
- Furnace combustion tubes and stack liners
- High-temperature chemical processing transfer lines
Aerospace · Petrochemical · Energy · Automotive
Performance scores in full
The same six scores the profile plots, as numbers.
| Property | 321 |
|---|---|
| Corrosion resistance | 7.8 / 10 |
| Weldability | 8.8 / 10 |
| High-temperature resistance | 8.8 / 10 |
| Tensile strength | 6.2 / 10 |
| Cold formability | 8.5 / 10 |
| Machinability | 4.2 / 10 |
This page is guidance for selecting a grade, not a specification. Design to the governing standard and the mill certificate for the heat you are supplied.
The specifications and data on this site are provided for general information only. Verify any real-world project with a qualified metallurgist before relying on these figures. We take no responsibility for the use and application of this information.