329

Data verified

329 is the original commercial duplex stainless (the JIS SUS329J1 family), a 25% chromium, low-nickel ferritic-austenitic grade that predates the modern lean and 2205 duplexes. It still appears in Japanese and legacy specifications for chemical and seawater-adjacent equipment.

Hardness≤277 HB
DIN1.4460
AISI329 (UNS S32900)
JISSUS329J1
CategoryStainless Steel

Chemical composition

ElementContent (%)
C≤0.08
Si≤0.75
Mn≤1.00
P≤0.040
S≤0.030
Cr23.00–28.00
Ni2.50–5.00
Mo1.00–2.00

Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.

Properties

Delivery conditionSolution annealed
Hardness≤277 HB
Tensile strength≥620 MPa
Yield strength≥450 MPa
Density7.80 g/cm³
MagneticYes

Heat treatment

Solution anneal 1010–1120 °C, rapid cool. As an early-generation duplex it is less forgiving of slow cooling and welding excursions than 2205.

Equivalent grades

StandardDesignation
din1.4460
aisi329 (UNS S32900)
jisSUS329J1

Compare side by side: 329 vs 2205 Duplex · 329 vs 2304 Duplex

Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.

Applications & Processing

Applications: Heat exchangers, chemical plant components, desalination (legacy), shafts and parts in Japanese-spec equipment.

Processing: Weldable with duplex practice but with a narrower procedure window than 2205; most buyers today substitute 2205 unless the drawing names 329/SUS329J1 explicitly.

FAQ

Can 2205 replace 329?
In most new fabrication yes — 2205 has a tighter, more weld-friendly composition and better availability. For certified replacement-in-kind against a SUS329J1 drawing, substitution needs the design authority’s approval.

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Source: ASTM A240 published ranges (UNS S32900) · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.