Stainless Steel 329
AISI/SAE 329 · UNS S32900
AISI 329 is one of the original commercial duplex stainless steels, a 25Cr-4Ni-1.5Mo grade covered by UNS S32900 and EN 1.4460 (X3CrNiMoN27-5-2).
Reference datasheet — 329 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Annealed condition
329 tempers and conditions
329 is supplied in 4 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Forged and solution annealed (ASTM A182 F329-type fittings/flanges) | Forged flanges, fittings and valve bodies; properties depend on section size and quench effectiveness. | 520 | 690 | 22 | 23 HRC | 2.2 % IACS |
As-welded deposit | Reference condition for fabricated joints; HAZ ferrite content rises sharply and toughness/corrosion resistance drop — solution anneal after welding whenever possible. | 520 | 700 | 15 | 25 HRC | 2.2 % IACS |
AnnealedDefault solution annealed ~950–1050 °C + rapid quench | Standard supplied condition for plate, sheet, bar, pipe and tube; best combination of corrosion resistance and ductility. | 540 | 720 | 25 | 22 HRC | — |
Cold drawn | Choose for tight-tolerance shafting, fasteners and pump parts where extra strength and a bright surface are wanted. | 700 | 860 | 16 | 29 HRC | — |
Supply forms, finishes and certifications
Ways 329 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
HRB-Bar | Hot Rolled / Hot Finished bar, annealed | Supply form |
Tube-A789 | Seamless / welded tubing, solution annealed | Supply form |
CRA-2B | Cold Rolled, Annealed and Pickled sheet, 2B finish | Surface finish |
HRAP | Hot Rolled, Annealed and Pickled plate | Surface finish |
What is 329?
AISI 329 is one of the original commercial duplex stainless steels, a 25Cr-4Ni-1.5Mo grade covered by UNS S32900 and EN 1.4460 (X3CrNiMoN27-5-2). It provides 540 MPa yield, 720 MPa tensile and 25 % elongation at 230 HB (22 HRC), and is found mainly as A789 heat exchanger tube, hot-rolled annealed and pickled plate, 2B cold-rolled sheet, cold-drawn bar and forgings. Low nitrogen content leaves a brittle, ferrite-rich weld HAZ, so welded assemblies normally need re-solution annealing, and service is limited to about 290 °C. Nitrogen-alloyed 2205 (1.4462) has largely replaced it in new designs. 329 has a density of 7.8 g/cm³ (0.282 lb/in³), heavier than 50% of stainless steel grades. It melts at 1,400°C (2,552 °F). 329 has a yield strength of 540 MPa (78.3 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 82% of stainless steel grades. Elongation at break is 25% and the elastic modulus is 200 GPa (29 Msi).
What is 329 used for?
- heat exchanger tubes
- condenser tubing
- refinery equipment
Advantages
- High strength — 540 MPa (78.3 ksi), better than 82% of stainless steel grades
Limitations
- Limited service temperature — 290°C (554 °F), worse than 94% of stainless steel grades
- Difficult to weld — 45/100, worse than 79% of stainless steel grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 77% of stainless steel grades
329 properties
Typical room-temperature values for 329-Annealed; bars are the position among stainless steel grades.
Physical3
329 has a density of 7.8 g/cm³ (0.282 lb/in³), heavier than 50% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical17
329 has a yield strength of 540 MPa (78.3 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 82% of stainless steel grades. Elongation at break is 25% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
329 is rated for continuous service to 290°C (554 °F). It conducts heat at 15.5 W/m·K (8.96 BTU/hr·ft·°F), better than 53% of stainless steel grades. Thermal expansion is 10.9 µm/m·K (6.06 µin/in·°F).
Electrical3
329 conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (72/100), better than 73% of stainless steel grades.
Sustainability4
Producing a kilogram of 329 takes about 55 MJ of energy and emits 5.5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
329's machinability is poor (30/100, worse than 70% of stainless steel grades); weldability fair (45/100); formability fair (40/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. 329 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 329
Is 329 easy to machine?
Machine like duplex: rigid setups, positive-rake coated carbide, 30–60 % of the speed used on 316L, heavy constant feed to cut under the work-hardened layer, generous flood coolant.
Can 329 be welded?
Weldable with GTAW/GMAW/SMAW using over-alloyed duplex or 309Mo/25-9-4 fillers; keep heat input moderate, interpass <150 °C, and solution anneal + quench after welding where the design allows, since the low nitrogen content leaves a brittle, ferrite-rich HAZ.
Can 329 be formed, bent or molded?
Cold forming needs roughly twice the force of 304 with large springback allowance; hot work 1000–1150 °C followed by full solution anneal and water quench — never air-cool from hot working.
329 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CASTM A240 S32900 max 0.20 %; modern melts run far lower | ≤ 0.2 | 0.06 |
| Mn | ≤ 1 | 0.6 |
| Si | ≤ 0.75 | 0.5 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.03 | 0 |
| Cr | 23 – 28 | 25.5 |
| Ni | 2.5 – 5 | 4.2 |
| Mo | 1 – 2 | 1.5 |
| Nnot specified in the original AISI 329; EN 1.4460 specifies 0.05–0.20 N | ≤ 0.1 | 0.06 |
| Fe | balance | — |
What surface finishes work on 329?
Pickle and passivate (HNO₃/HF) after hot work or welding to restore the passive film; takes a good mechanical or electropolished finish, but the two-phase structure can etch with slight relief.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 329 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 329 cost?
329 is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
329 — frequently asked
What is 329 used for?
329 is typically used for heat exchanger tubes, condenser tubing and refinery equipment. In short: original commercial duplex grade; legacy heat-exchanger tube stainless; post-weld anneal usually required.
What is the yield strength of 329?
329 has a typical yield strength of 540 MPa (78.3 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 82% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is 329 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 70% of stainless steel grades). Machine like duplex: rigid setups, positive-rake coated carbide, 30–60 % of the speed used on 316L, heavy constant feed to cut under the work-hardened layer, generous flood coolant.
Can 329 be welded?
With care — weldability is rated fair (45/100). Weldable with GTAW/GMAW/SMAW using over-alloyed duplex or 309Mo/25-9-4 fillers; keep heat input moderate, interpass <150 °C, and solution anneal + quench after welding where the design allows, since the low nitrogen content leaves a brittle, ferrite-rich HAZ.
What surface finishes work on 329?
Pickle and passivate (HNO₃/HF) after hot work or welding to restore the passive film; takes a good mechanical or electropolished finish, but the two-phase structure can etch with slight relief.
Can 329 be formed, bent or molded?
Cold forming needs roughly twice the force of 304 with large springback allowance; hot work 1000–1150 °C followed by full solution anneal and water quench — never air-cool from hot working.
What is the maximum service temperature of 329?
329 is rated for continuous use to about 290°C (554 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 329 Annealed and 329-CD?
Annealed is the default condition — standard supplied condition for plate, sheet, bar, pipe and tube; best combination of corrosion resistance and ductility. CD: choose for tight-tolerance shafting, fasteners and pump parts where extra strength and a bright surface are wanted. Yield strength is 540 MPa in Annealed versus 700 MPa in CD.
How much does 329 cost?
329 is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip — ASTM International (2023)
- ASTM A789/A790 — Ferritic/Austenitic Stainless Steel Tubing and Pipe — ASTM International (2021)
- EN 10088-1/-2 — Stainless steels, grade 1.4460 (X3CrNiMoN27-5-2) — CEN (2014)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.