Products Features
Exceptional resistance to pitting and crevice corrosion (core advantage)
One of the core advantages of S32654 is its extremely high resistance to pitting corrosion and crevice corrosion. The synergistic effect of high chromium (23-25%), high molybdenum (6.0-8.0%), and high nitrogen (0.45-0.55%) results in a PREN value of 54-57, which is significantly higher than that of 316L (≈25), 904L (≈34), and S31254 (≈42-45). In harsh environments such as seawater, chloride solutions, and acidic chloride media, S32654 can form an extremely stable passive film, resisting the initiation and propagation of pitting and crevice corrosion. Its critical pitting temperature (CPT) can reach above 85°C, far exceeding that of 316L (≈15°C), 2205 (≈35°C), and 254 SMO (≈60°C). It can operate reliably for a long time without pitting perforation in tropical seawater and high-temperature concentrated chloride solutions. This property makes it an ideal material selection for extreme chloride environments such as offshore platforms, seawater desalination, and heat exchangers.
Excellent stress corrosion cracking resistance
The high nickel content (21-23%) and fully austenitic microstructure of S32654 endow it with excellent resistance to stress corrosion cracking (SCC) in chloride-containing environments. Conventional austenitic stainless steels such as 304L and 316L are highly susceptible to intergranular SCC in chloride aqueous solutions above 60°C. In contrast, S32654 exhibits significantly superior SCC resistance to 316L and 304L even under high-stress, high-temperature chloride conditions. Combined with an extremely high PREN (≥ 54), this material possesses exceptional SCC resistance in extreme scenarios where high chloride ion levels and stress coexist.
Excellent corrosion resistance to strong reducing acids
The high molybdenum and nickel content of S32654 endows it with excellent corrosion resistance in strongly reducing acidic media. In media such as sulfuric acid (concentration ≤60%), phosphoric acid, formic acid, and acetic acid, the corrosion resistance of S32654 is far superior to that of 316L, 317L, and 904L, and approaches or even reaches the level of nickel-based alloy C-276. This property makes it an ideal material selection for applications involving strongly reducing acidic conditions in chemical processing, pharmaceuticals, hydrometallurgy, and other fields. It is also a high-value, cost-effective alternative to expensive nickel-based alloys.
Good machining and welding properties
S32654 exhibits excellent hot and cold workability, enabling various forming processes such as forging, hot rolling, cold rolling, stamping, and bending. Compared to ferritic and duplex stainless steels, its fully austenitic microstructure makes it more formable and weld-friendly, with a moderate work hardening rate. It can be joined using multiple welding methods including TIG, MIG, SMAW, and SAW. When welding, it is recommended to use matching filler materials such as ERNiCrMo-3 or ERNiCrMo-4 to prevent reduced corrosion resistance in the weld area. Post-weld heat treatment is typically not required, but pickling or passivation is recommended to restore corrosion resistance.
Excellent fatigue resistance
S32654 exhibits excellent fatigue resistance. Its combination of high strength and good toughness enables it to perform exceptionally well under cyclic loading conditions. In seawater and chloride environments, its fatigue crack growth resistance is superior to that of conventional austenitic stainless steels and duplex stainless steels, making it suitable for components such as marine structural parts, pump shafts, and impellers that are subjected to alternating loads.
Technical Specifications
Chemical Composition(ASTM A240 / UNS S32654)
|
Element |
Standard Requirements |
Notes |
|
Cr |
23.0 - 25.0% |
Core elements form a dense passivation film, providing corrosion resistance |
|
Ni |
21.0 - 23.0% |
Austenite stabilizing elements that enhance toughness and stress corrosion cracking resistance, ensuring microstructural stability |
|
Mo |
6.0 - 8.0% |
Improves resistance to pitting and crevice corrosion by approximately three times that of chromium |
|
N |
0.45 - 0.55% |
Strong austenite-forming elements, solid solution strengthening, significantly improve pitting corrosion resistance and yield strength |
|
Mn |
2.0 - 4.0% |
Deoxidizer, while increasing the solubility of nitrogen |
|
Cu |
0.3 - 0.6% |
Improve corrosion resistance in reducing acids (such as sulfuric acid) |
|
Si |
≤ 0.50% |
Deoxidizer, strictly controlled |
|
C |
≤ 0.020% |
Strictly control to prevent the precipitation of carbides from impairing corrosion resistance |
|
P |
≤ 0.030% |
Impurity elements, strictly controlled |
|
S |
≤ 0.010% |
Impurity elements, strictly controlled |
|
Fe |
Remaining quantity (≈ 44%) |
Matrix element |
Physical Properties
|
Property |
Value/Range |
Test Conditions |
|
Density |
8.0 g/cm³ |
Room temperature (20°C) |
|
Melting Point |
1320 - 1400°C |
- |
|
Thermal Conductivity |
≈ 13 W/(m·K) |
Room temperature |
|
Coefficient of thermal expansion (20-100°C) |
≈ 15.5 × 10⁻⁶ /K |
Typical austenitic stainless steel |
|
Resistivity |
≈ 0.85 μΩ·m |
Room temperature |
|
Elastic modulus (Young's modulus) |
195 GPa |
Room temperature |
|
Poisson's ratio |
0.30 |
Room temperature |
|
Magnetism |
Non-magnetic |
Fully austenitic microstructure, non-magnetic |
Mechanical Properties (Solution Annealed Condition, Typical Values, ASTM A240)
|
Property |
Typical Value |
Specification |
|
Tensile Strength |
≥ 750 MPa |
ASTM A240 |
|
Yield Strength (0.2% Offset) |
≥ 430 MPa |
ASTM A240 |
|
Elongation |
≥ 35% |
ASTM A240 |
|
Hardness (Brinell) |
≤ 250 HB |
- |
Note: The yield strength of S32654 is approximately twice that of 316L and about 1.4 times that of 254 SMO, which can significantly reduce wall thickness to achieve structural lightweighting and cost optimization. Its PREN ≥ 54, making it one of the stainless steel grades with the strongest pitting corrosion resistance among all commercialized stainless steels.
Pitting Resistance Equivalent Number (PREN) Comparison
|
Material grade |
PREN(Cr+3.3Mo+16N) |
Chloride resistance |
|
S32654 (654 SMO®) |
54 - 57 |
Excellent |
|
S31254 (254 SMO®) |
42 - 45 |
Excellent |
|
904L (N08904) |
≈ 34 |
Outstanding |
|
316L |
≈ 25 |
General |
|
S32750 (2507) |
≥ 40 |
Excellent |
Corrosion Resistance (Typical Value)
|
Medium |
Concentration |
Temperature |
Corrosion rate |
Rating |
|
Seawater |
- |
Room temperature to 100°C |
Ignored |
Excellent |
|
Chloride solution (salt water) |
- |
High temperature |
Ignored |
Excellent |
|
Nitric acid (HNO₃) |
≤ 40% |
Room temperature |
＜0.05 |
Outstanding |
|
Sulfuric Acid (H₂SO₄) |
≤ 60% |
Room temperature |
＜0.05 |
Outstanding |
|
Hydrochloric acid (HCl) |
Low concentration |
Room temperature |
＜0.1 |
Good |
|
Phosphoric acid (H₃PO₄) |
- |
Room temperature |
Ignored |
Outstanding |
|
Sodium hydroxide (NaOH) |
- |
Room temperature |
Ignored |
Outstanding |
|
Organic acids (such as acetic acid, formic acid, etc.) |
- |
Room temperature |
Ignored |
Outstanding |
|
Wet Chlorine Gas |
- |
Room temperature |
Ignored |
Outstanding |
Note: The corrosion resistance of S32654 is far superior to that of 316L, 317L, and 904L in most environments. It performs excellently in reducing acid media such as sulfuric acid, phosphoric acid, and acetic acid, comparable to nickel-based alloy C-276. However, its corrosion resistance is limited in extreme strongly reducing media such as high-temperature concentrated hydrochloric acid and hydrofluoric acid.
High-temperature performance
S32654 maintains high strength at moderate temperatures:
|
Temperature |
Tensile strength (MPa, approximately) |
Performance retention rate |
|
Room Temperature (20°C) |
≥ 750 |
100% |
|
100°C |
≈ 680 |
≥ 90% |
|
200°C |
≈ 620 |
≥ 83% |
|
300°C |
≈ 570 |
≥ 76% |
Long-term Thermal and Microstructural Stability:
S32654 exhibits good microstructural stability when in service at temperatures ≤ 300°C, with no risk of embrittlement from sigma phase formation in its fully austenitic structure. However, prolonged exposure within the 600-1000°C range may lead to precipitation of sigma and chi phases, which can reduce corrosion resistance and toughness; thus, long-term use in this temperature interval should be avoided. Compared to duplex stainless steels, S32654 maintains better microstructural stability at elevated temperatures.
Hot Working and Heat Treatment
The heat treatment of S32654 has a decisive impact on the final microstructure and properties, with common specifications as follows:
1. Solution Treatment (for optimal corrosion resistance and comprehensive properties):
Heat to 1150-1200°C, hold for sufficient time (approximately 2-4 minutes per inch of thickness), then water quench or rapid air cool. This process is performed to achieve the best corrosion resistance and mechanical properties. The solution treatment temperature for S32654 is higher than that for 254 SMO, which is determined by its higher alloy content.
2. Stress relief treatment (after welding/cold working):
Heat to 650-750°C, hold for 1-2 hours, then air cool. This is used to eliminate residual stresses. However, note that sigma phase precipitation may occur in this temperature range; it is recommended to carefully assess the impact on corrosion resistance.
Note:
- Heat treatment should quickly pass through the sensitive temperature range of 600-1000°C to avoid the precipitation of σ phase and χ phase
- The solution treatment temperature should not be too high (> 1200°C), otherwise the coarse grain structure will adversely affect mechanical properties.
- It is recommended to perform pickling or passivation after heat treatment to remove surface scale
Welding Performance and Process Key Points
S32654 has good welding properties, but the following points should be noted:
1. Recommended welding methods: TIG (GTAW), MIG (GMAW), SMAW, SAW.
2. Heat input control: It is recommended to maintain a heat input of 0.5-2.5 kJ/mm, with interpass temperature ≤ 150°C, to avoid grain coarsening and sensitization in the heat-affected zone.
3. Protective gas: A mixed gas of Ar + 1-2% N₂ is recommended, which can increase the nitrogen content in the weld metal and improve its corrosion resistance.
4. Filler metal: Over-matched welding materials such as ERNiCrMo-3 or ERNiCrMo-4 are recommended to ensure that the weld metal's corrosion resistance is not lower than that of the base metal.
5. Post-weld treatment: It is recommended to perform pickling or passivation to restore the corrosion resistance of the heat-affected zone and remove welding oxidation discoloration.
Applicable Media
1. Seawater and chloride solutions: Exhibits excellent resistance to pitting corrosion, crevice corrosion, and stress corrosion cracking, allowing for pitting-free operation in seawater up to 100°C.
2. Oxidizing acids: Such as nitric acid (≤40%), with outstanding corrosion resistance.
3. Strong reducing acids: Such as sulfuric acid (≤60%) and phosphoric acid, with excellent corrosion resistance approaching that of nickel-based alloys.
4. Organic acids: Including acetic acid, formic acid, citric acid, etc.
5. Alkaline solutions: Such as sodium hydroxide, potassium hydroxide, etc.
6. Chlorine-containing gas media: Environments in oil and natural gas exploration and processing.
7. High-temperature water vapor (temperature limitations should be noted).
Note: S32654 is not resistant to extreme strongly reducing media such as hydrofluoric acid and high-temperature, high-concentration hydrochloric acid.
S32654 (654 SMO®) is an upgraded alternative to 254 SMO, suitable for stringent applications with high requirements for comprehensive corrosion resistance, chlorine resistance, and acid resistance. It is recommended for use in the following fields:
Application Fields
-
Oil and Natural Gas Industry
● Oil and gas field pipeline systems, submarine pipelines
● Downhole tools, wellhead equipment, valves, pipe fittings, flanges
● Separator, heat exchanger, pump and valve components
● Drilling platform modules, fire protection systems -
Marine Engineering and Seawater Desalination
● Desalination plant pipelines, high-pressure reverse osmosis (RO) units
● Offshore platform structural components, seawater heat exchangers (capable of operating without pitting corrosion in 100°C seawater)
● Ship ballast water system, fire water system -
Electric Power Industry
● FGD flue gas desulfurization system, absorber tower, pipelines and flue gas ducts
● Nuclear power plant cooling water system
● Geothermal power generation equipment -
Environmental Protection and Wastewater Treatment
● Wastewater treatment system, exhaust gas scrubber tower
● Waste incineration flue gas treatment equipment -
Pulp and Paper Industry
● Steam cooker, bleaching equipment (ClO₂ environment), washer -
Pharmaceutical and Food Industries
● Reaction vessels, fermenters, storage tanks -
Chemical Processing and Petrochemical Engineering
● Pressure vessels, high-pressure tanks, reactors
● Heat exchangers, condensers, evaporators
● Pipeline system for conveying corrosive media (including chloride environments)
● Equipment for treating with sulfuric acid, phosphoric acid, acetic acid, etc.
● Distillation column, absorption tower, separator
● An ideal material to replace high-cost nickel-based alloys
Delivery and Customization
We offer flexible and reliable supply chain solutions to ensure you receive S32654 materials that perfectly match your project requirements.
|
Form |
 Sheet/Plate
|
 Bar/Rod
|
 Pipe / Tube
|
 Strip/Sheet Coil
|
 Wire/Wire Rod
|
|---|---|---|---|---|---|
|
Conventional Range |
Thickness: 0.5 - 100 mm |
Diameter Φ6-500mm |
Outer diameter Φ10-300mm |
Thickness: 0.05 – 3.0 mm |
Diameter Φ0.1-10mm |
|
Customization Capability |
Hot-rolled or cold-rolled plates, ultra-thin plates (starting from 0.1mm), stamped parts, length-cutting to specified dimensions, special surface treatments (pickling, polishing) |
Forged bars, hot-rolled bars, polished bars, shaped bars, and different heat treatment conditions (solution-treated condition) |
Seamless Tubes/ Welded Tubes (Compliant with ASTM A312/ A269), Fixed-Length Cutting, U-Tubes |
Precision strip materials, stamping coil stock, laminated blanking, non-standard width, special protective film |
Precision drawing, welding filler wires (ERNiCrMo-3/4), special surface treatment |
Why Choose Us? - Reliable Engineering Technology. Dependable Delivery.
We are not just a supplier, but a trusted materials partner for you in China.
Vertically Integrated Production
Own 20,000㎡ facility with 10+ automated lines (8,000+ tons/year). In-house tooling & die center enables rapid customization and effective cost control - no middleman markup.
Strict Quality Control at Every Stage
Full traceability across key QC checkpoints throughout production. 100% compliant with ASTM/ASME, EN, and GB standards. Material test reports available with every shipment.
Reliable Delivery & Export Packaging
10+ years exporting to Europe, North America, Southeast Asia & Middle East with waterproof and anti-rust protection, combined with flexible shipping options ensures safe and on-time arrival.
Sample Validation Before Mass Production
We provide free samples for quality verification, allowing you to place bulk orders only after approval. We ensure consistency from sample to mass production by accurate dimensional measurement and transparent manufacturing.
FAQ
Q: What are the main advantages of S32654 (654 SMO®)?
Q: What is the difference between S32654 and 254 SMO (S31254)? How to choose between them?
Q: What is the difference between S32654 and 316L? How to choose between them?
Q: What is the maximum service temperature for S32654?
Q: What is the welding performance of S32654?
Q: Can S32654 replace 316L or 254 SMO?
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