321 is 304 stabilized with titanium. The titanium ties up carbon as titanium carbide so chromium stays in solution, which prevents the sensitization that otherwise attacks the weld heat affected zone and any part held in the 800F to 1500F range.
That makes it the standard grade for welded exhaust systems, manifolds, expansion joints and high temperature ducting that cannot be solution annealed after welding.
Stocked as sheet, plate, bar and tube. 321H, with a controlled higher carbon range, is available where creep strength at temperature is specified.
Sizes and stock
- Round bar: up to 10" DIA
- Flat bar: up to 12" THK
- Sheet / plate: up to 4" THK
- Coil / foil: from .0005" THK
- Wire: from .015" DIA
- Tube: various sizes
- Forgings: available by request
Processing capabilities
- Shearing, waterjet, laser and saw cut blanks
- Centerless grinding, turning and polishing
- Penetrant dye and ultrasonic inspection, chemical assay and physical testing
Specifications
Material is released to the applicable specification with mill test reports and, on request, independent lab verification.
Why engineers specify 321
- Resists sensitization in welded and elevated temperature service
- Good oxidation resistance to roughly 1500F
- Retains the formability and weldability of the 300 series
- 321H available for creep rated service
Nominal chemistry
Percent by weight, nominal composition per the governing specification. The mill test report for your heat is the controlling document.
Typical mechanical properties
| Condition | Tensile strength | Yield strength | Elongation | Hardness |
|---|---|---|---|---|
| Annealed | 75 ksi min | 30 ksi min | 40% min | - |
Typical published values for reference only, not for design. Properties vary with section size, product form and processing. Order to the specification and condition your drawing requires.
Typical applications
- Aircraft exhaust and ducting
- Expansion joints and bellows
- Heat exchangers
- Welded high temperature assemblies
Fabrication notes
Machining
Austenitic grades work harden quickly, so use positive rake tooling, rigid setups, generous feed and flood coolant rather than light dwelling cuts. Martensitic and precipitation hardening grades machine most easily in the annealed or solution treated condition and are aged after rough machining.
Welding
Weldable by GTAW, GMAW, resistance and electron beam methods with matching or over alloyed filler. Stabilized and low carbon grades resist sensitization in the weld zone. Precipitation hardening grades are normally welded in the solution treated condition and aged afterward.
Forming
Sheet and strip form well in the annealed condition; cold worked tempers trade formability for strength. Allow for springback and, where specified, an intermediate anneal between draws.
321 compared with similar grades
347
Niobium stabilized alternative with similar behaviour, often preferred for welded pressure parts.
304L
Low carbon alternative for welded service at ambient temperature only.
Designations and cross reference
- Material family
- Stainless Steel
- Werkstoff (W.Nr)
- 1.4541
- EN designation
- X6CrNiTi18-10
- Series
- 300 Series
Working from an obsolete, foreign or superseded designation? Send it over and we will cross reference it to a current grade and specification.
Quality, testing and traceability
Supplied with mill test reports and heat traceability, with penetrant dye, ultrasonic, chemical assay, hardness, corrosion and mechanical testing available on request.
We are AS9100D and ISO 9001:2015 registered. If our stock does not already carry the inspection your specification requires, we can quote the material with that work performed. More on our quality system
Available forms
321 frequently asked questions
What is 321?
321 is 304 stabilized with titanium. The titanium ties up carbon as titanium carbide so chromium stays in solution, which prevents the sensitization that otherwise attacks the weld heat affected zone and any part held in the 800F to 1500F range.
What forms is 321 available in?
We supply 321 in bar, sheet, plate, coil, foil, wire, tube, forging. Custom sizes are converted from billet, and we can provide saw cut, waterjet or near net blanks so material arrives closer to your finished part.
What is the UNS or equivalent designation for 321?
321 is designated Werkstoff 1.4541, EN X6CrNiTi18-10. If your drawing calls out an obsolete or foreign designation we can cross reference it and confirm the equivalent before you order.
What specifications can 321 be supplied to?
Commonly ordered specifications include AMS 5510, AMS 5645, AMS 5570, AMS 5576, AMS 5689, AMS 5557. Material is released to the specification and condition on your purchase order, with mill test reports supplied as standard.
What conditions can 321 be ordered in?
We can supply Annealed. If our stock is not already in the condition you need, we can quote it with the heat treatment performed before shipment.
Can you cut 321 to size?
Yes. Saw cutting, waterjet, laser and shearing are available, along with trepanning, gun drilling, lathe turning and CNC machining, so you can order blanks or rough machined pieces rather than full lengths.
Do you provide test reports and additional testing on 321?
Every order ships with mill test reports and heat traceability. If your print calls for ultrasonic inspection, penetrant dye, magnetic particle, chemical assay, micrography, hardness or mechanical testing and our stock does not already carry it, we can quote the material with that work performed.
Can 321 be supplied to DFARS domestic melt requirements?
Tell us at quote stage if the order is DFARS or domestic melt restricted and we will confirm availability against that requirement before you commit.
What do you need to quote 321?
Grade, form, dimensions, quantity, specification and condition, plus any testing or certification requirements and the date you need it. Send a drawing if you have one. Quotes are typically ready within 24 hours.
How does 321 compare with 347?
Niobium stabilized alternative with similar behaviour, often preferred for welded pressure parts.