AISI 329 Stainless Steel Plate | A240 Type 329 | UNS S32900
What is AISI 329 Stainless Steel?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 329 Stainless Steel Plate.
AISI 329 is widely known and searched under many different names and designations, including AISI 329, ASTM A240 Type 329, ASME SA240 Type 329, UNS S32900, 329 stainless steel, 329 stainless steel plate, 1.4460, X3CrNiMoN27-5-2, duplex 329 and 25Cr duplex 329. All these names refer to the same classic duplex stainless steel with a mixed austenite-ferrite microstructure.
AISI 329 typically contains about 23–28% chromium, 2.5–5% nickel and 1–2% molybdenum. The dual-phase structure gives higher yield strength than austenitic a240 304 or a240 316l, plus useful resistance to chloride stress-corrosion cracking. It is magnetic because of the ferrite phase.
329 is an older duplex grade. For many new projects, modern lean or standard duplex grades such as a240 2304 and a240 2205 are specified instead because of improved weldability and tighter phase balance. AISI 329 remains relevant when the drawing names Type 329 / UNS S32900, or when a high-chromium duplex plate is required.
SHH STEEL supplies AISI 329 as true China steel mill-Direct Supply, sourcing directly from major Chinese stainless steel mills. This model delivers competitive mill pricing, consistent quality, complete heat traceability and reliable delivery.
AISI 329 is frequently compared with a240 2205, a240 2507, a240 2304, a240 316l, A240 904L and a240 304. SHH STEEL provides technical support to help customers choose the most appropriate duplex or austenitic grade.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Grade | AISI 329 / A240 Type 329 / UNS S32900 | Confirmed |
| Related Standards | ASTM A240, ASME SA240, EN 1.4460 related | Available |
| Product Form | Plate, Sheet | Available |
| Delivery Condition | Solution annealed | Standard |
| Thickness Range | 1 mm – 50 mm (thicker available on request) | Custom sizes supported |
| Width | Up to 1500–2000 mm | Available |
| Length | Up to 6000–12000 mm or cut-to-length | Available |
| Surface Finish | No.1, 2B, and others on request | Available |
| Certification | EN 10204 3.1 / Mill Test Certificate | Available |
SHH STEEL can supply dual-certified ASTM A240 / ASME SA240 Type 329 material when required by the project.
Chemical Composition
Typical Chemical Composition of AISI 329 (UNS S32900):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Silicon (Si) | ≤ 0.75 |
| Manganese (Mn) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 23.00 – 28.00 |
| Nickel (Ni) | 2.50 – 5.00 |
| Molybdenum (Mo) | 1.00 – 2.00 |
| Iron (Fe) | Balance |
The defining features of AISI 329 are high chromium plus moderate nickel and molybdenum in a duplex (austenite + ferrite) structure. High chromium supports pitting resistance. Nickel balances the austenite fraction. Molybdenum improves chloride resistance. SHH STEEL carefully controls this chemistry so phase balance and corrosion performance stay consistent.
Mechanical Properties
Solution-Annealed Condition (typical ASTM A240 values)
| Property | Value |
|---|---|
| Tensile Strength | ≥ 620 MPa (90 ksi) |
| Yield Strength (0.2%) | ≥ 485 MPa (70 ksi) |
| Elongation (in 50 mm) | ≥ 15% |
| Hardness | ≤ 30 HRC / 293 HBW typical max |
AISI 329 has much higher yield strength than 304 or 316L, so designers can often use thinner plate for the same load. Ductility is lower than austenitic grades. The material is magnetic. SHH STEEL supplies AISI 329 in the solution-annealed condition unless otherwise specified.
Physical Properties
Density is approximately 7.80 g/cm³. Melting range is approximately 1400–1450°C.
Material Comparison
| Grade | UNS | Structure | PREN (approx.) | Strength vs 316L | Typical Preference |
|---|---|---|---|---|---|
| AISI 304 | S30400 | Austenitic | ~18 | Lower | General corrosion service |
| AISI 316L | S31603 | Austenitic | ~24 | Lower | Process chlorides |
| AISI 2304 | S32304 | Lean duplex | ~26 | Higher | Modern lean duplex |
| AISI 2205 | S32205 | Duplex | ~35 | Higher | Standard modern duplex |
| AISI 329 | S32900 | Duplex | ~32–36 | Higher | Classic 25Cr duplex / named 329 specs |
| AISI 2507 | S32750 | Super duplex | ~42 | Highest | Severe chloride / seawater |
AISI 329 is selected when the specification names Type 329 / UNS S32900. For new chloride-service designs, SHH STEEL often recommends a240 2205 or a240 2507 because of more tightly controlled nitrogen and phase balance. For milder duplex needs, compare with a240 2304.
Corrosion Resistance
AISI 329 offers good resistance to pitting, crevice corrosion and chloride stress-corrosion cracking compared with 304 and 316L, because of high chromium, molybdenum and the duplex structure.
It is used in chemical process equipment, pulp and paper, and chloride-containing waters. For the most severe seawater or high-temperature chloride service, SHH STEEL recommends a240 2507 or A240 904L. Heat input and cooling rate after welding must be controlled to avoid intermetallic phases that reduce corrosion resistance.
Weldability
AISI 329 can be welded by standard fusion methods, but procedure control is more demanding than for 304/316L. Heat input should be limited and interpass temperature kept low to preserve phase balance and avoid sigma phase.
Matching duplex or over-alloyed fillers are selected according to the design. For easier welding and more predictable HAZ properties on new projects, SHH STEEL often recommends a240 2205. Post-weld cleaning and passivation are required.
Heat Treatment
AISI 329 is normally supplied in the solution-annealed condition by SHH STEEL.
Solution annealing is typically performed around 1020–1100°C followed by rapid cooling to restore the austenite-ferrite balance and corrosion resistance. The grade cannot be hardened by conventional quench and temper. Slow cooling through 700–900°C should be avoided because intermetallic phases can form.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| No.1 | Hot-rolled, annealed and pickled | AISI 329 No.1 / A240 329 No.1 – industrial plate |
| 2B | Cold-rolled, annealed, pickled, skin-passed | AISI 329 2B – thinner plate and sheet |
| Special | Ground or custom finishes | AISI 329 Special – on request |
SHH STEEL regularly supplies AISI 329 in No.1 and 2B finishes.
Tolerances
Dimensional tolerances for AISI 329 Stainless Steel Plate supplied by SHH STEEL generally conform to ASTM A480 practices.
Typical available size range is thickness 1 mm – 50 mm, width up to 1500–2000 mm, and length up to 6000–12000 mm or cut-to-length. SHH STEEL provides precise dimensional control and can support tighter tolerances when required.
Equivalent Material Grades
| Grade / Designation | Standard / Region | Notes |
|---|---|---|
| AISI 329 | AISI | Main commercial keyword |
| A240 Type 329 | ASTM A240 / ASME SA240 | Plate specification |
| UNS S32900 | Unified Numbering System | Primary UNS designation |
| 1.4460 / X3CrNiMoN27-5-2 | EN (Europe) | Closest European duplex |
| Related SUS329J1 | JIS (Japan) | Related Japanese duplex |
| Related 00Cr25Ni5Mo2 | GB/T (China) | Chinese related duplex |
| Related 2205 / 2304 / 2507 | Multiple | Modern duplex alternatives |
Related grades for comparison include a240 2205, a240 2507, a240 2304, a240 316l, A240 904L and a240 304.
Applications
AISI 329 is selected for high-strength duplex fabrications that need better chloride resistance than 304/316L. Typical applications of AISI 329 include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Chemical Processing | AISI 329 tanks, vessels and process piping |
| Pulp & Paper | AISI 329 digesters, bleach-plant and chloride-process parts |
| Oil & Gas / Petrochemical | AISI 329 heat-exchanger and process fabrications |
| Water & Desalination | AISI 329 chloride-service plate and fabricated parts |
| General Duplex Fabrication | A240 Type 329 No.1 plate for high-strength constructions |
| Equipment Manufacturing | AISI 329 covers, frames and welded duplex components |
SHH STEEL supplies AISI 329 for these duplex applications with consistent quality. For related industry solutions, see our petrochemical industry, energy industry and equipment manufacturing pages. Supporting services include steel cutting services, steel welding services and worldwide shipping service.
Why Choose SHH STEEL
SHH STEEL is a China steel mill-Direct Supply specializing in stainless steel plate and duplex grades. By working directly with major Chinese stainless steel mills, SHH STEEL supplies AISI 329 with the following advantages:
- Genuine China steel mill-Direct Supply pricing
- Consistent quality and complete heat traceability
- Full Mill Test Certificates (EN 10204 3.1)
- Classic 25Cr AISI 329 material supplied to A240 Type 329 / UNS S32900
- Flexible dimensions and surface finishes (including AISI 329 No.1 and AISI 329 2B)
- Technical support for selection among AISI 329, 2304, 2205, 2507 and 316L
- Value-added services including steel cutting services, steel welding services and worldwide shipping service
For more information about our company and full product range, please visit China steel Mill Agent-SHH STEEL.
FAQ
- What are the other common names for AISI 329?AISI 329 is also known as ASTM A240 Type 329, UNS S32900, 1.4460, X3CrNiMoN27-5-2 and duplex 329. SHH STEEL can certify the required designation.
- What is the difference between AISI 329 and AISI 2205?Both are duplex grades. 2205 is the modern standard duplex with tighter nitrogen and phase-balance control. 329 is the classic 25Cr duplex named on older specifications. SHH STEEL can supply either grade.
- Is AISI 329 magnetic?Yes. The ferrite phase makes AISI 329 magnetic, unlike 304 or 316L.
- What is the density of AISI 329?Approximately 7.80 g/cm³. SHH STEEL provides mill certificates confirming chemistry and mechanical properties.
- Can AISI 329 replace 316L?In many chloride and high-strength applications yes, and the higher yield strength can reduce thickness. For new designs, SHH STEEL often compares 2205 as well.
- Is AISI 329 easy to weld?It is weldable with controlled heat input. Procedure control is stricter than for 304/316L. SHH STEEL recommends qualified duplex welding procedures.
- : Does SHH STEEL supply dual-certified ASTM A240 Type 329 / AISI 329 material?Yes, SHH STEEL commonly supplies dual-certified material upon request.
Conclusion
AISI 329 Stainless Steel Plate is a classic 25% chromium duplex grade with high strength and better chloride resistance than 304 or 316L. It remains the correct choice when the specification names Type 329 / UNS S32900. For many new projects, modern 2205 or 2507 may also be considered.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality AISI 329 Stainless Steel Plate with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including AISI 329 No.1 and AISI 329 2B), comparison with 2205/2507, or a competitive quotation.
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