254SMO (UNS S31254 / 1.4547) is a super austenitic stainless steel designed for the most aggressive corrosion environments, especially where conventional stainless steels (304/316/904L) fail.
Its chemical design includes:
High molybdenum (Mo 6.0–6.5%)
High nickel (Ni 17.5–18.5%)
Nitrogen (N 0.18–0.22%)
These elements give 254SMO:
Extremely high pitting & crevice corrosion resistance
PREN ≥ 42 (super austenitic level)
Excellent resistance to chloride stress corrosion cracking
Superior performance in seawater, brine, and chemical processing
254SMO is widely used in:
Offshore & marine engineering
Desalination plants
Chemical processing
Pulp & paper industry
Heat exchangers & evaporators
High‑chloride industrial systems
It is one of the most corrosion‑resistant stainless steels available before moving into nickel‑based alloys.
🟦 Standards
ASTM A276
ASTM A479
EN 10088
UNS S31254
DIN/EN 1.4547
GB/T 1220 S31254
🟦 Grade Included
254SMO (UNS S31254 / 1.4547) — Super Austenitic Stainless Steel
🟦 Product Specifications & Available Sizes
Shapes Available
Round Bar
Square Bar
Hex Bar
Flat Bar
Diameter Range
6–500 mm
Length
1–12 m / custom cut
Surface Conditions
Hot Rolled
Cold Drawn
Peeled / Turned
Polished
🟦 Chemical Composition（254SMO）
Element
Content (%)
C
≤ 0.020
Mn
≤ 1.00
Si
≤ 0.80
P
≤ 0.030
S
≤ 0.010
Cr
19.5–20.5
Ni
17.5–18.5
Mo
6.0–6.5
N
0.18–0.22
📌 High Mo + high Ni + nitrogen = extreme corrosion resistance (PREN ≥ 42).
🟦 Mechanical Properties（Typical）
Property
Requirement
Tensile Strength
≥ 650 MPa
Yield Strength
≥ 300 MPa
Elongation
≥ 35%
Hardness
≤ 270 HB
🟦 Corrosion Resistance Performance
Environment
254SMO Performance
Seawater
Outstanding
Chlorides
Extremely High
Pitting Resistance
Very High (PREN ≥ 42)
Crevice Corrosion
Excellent
Stress Corrosion Cracking
Excellent
Acidic Environments
High
254SMO is often used as a cost‑effective alternative to nickel alloys such as Alloy 625.
🟦 Physical Properties
Property
Value
Density
8.00 g/cm³
Magnetic
Non‑magnetic
Thermal Conductivity
12 W/m·K
Corrosion Resistance
Extremely High
🟦 Manufacturing Processes
Hot Rolling
Cold Drawing
Turning / Peeling
Grinding / Polishing
Straightening
Ultrasonic Testing
🟦 Primary Industry Usage
Offshore platforms & seawater systems
Desalination plants (RO, MSF, MED)
Chemical processing & reactors
Heat exchangers & evaporators
Pulp & paper bleaching equipment
High‑chloride industrial systems
🟦 Why Use 254SMO Stainless Steel Bar
One of the highest corrosion‑resistant stainless steels
