254SMO (UNS S31254 / W.Nr. 1.4547) Super Austenitic Stainless Steel Round Bar

Product Highlights

• 254SMO high‑molybdenum super‑austenitic round bar, UNS S31254 / W.Nr 1.4547, manufactured to ASTM A276 / A479 bar specification
• 6Mo high‑alloy super‑austenitic grade, PREn ≥42.5, outstanding pitting & crevice‑corrosion resistance in high‑chloride media
• Ultra‑low carbon plus Cu‑N alloying, excellent performance for seawater, brine, flue‑gas desulfurization and mixed‑acid service conditions
• Fully austenitic microstructure, non‑magnetic after solution annealing, excellent toughness from cryogenic up to 400 °C working temperature
• Superior chloride SCC resistance compared to conventional 316L / 904L austenitic stainless steels
• Supplied in solution‑annealed water‑quenched condition for homogeneous single‑phase austenite and good machinability
• Custom diameter, length & full‑scope CNC turning, milling, threading per customer CAD/PDF drawings
• Premium raw stock for seawater desalination, offshore marine, power‑plant FGD, chemical‑process and high‑corrosion pump‑valve components

Product Overview

This series of 254SMO (S31254) super‑austenitic stainless steel round bars are manufactured via hot‑rolling, forging or cold‑drawing, followed by strict solution annealing and rapid water quenching to achieve uniform single‑phase austenitic microstructure. Standard delivery is soft solution‑annealed blank ready for full‑range CNC rough‑and‑finish machining.

254SMO is well‑known 6‑molybdenum super‑austenitic stainless steel. High molybdenum, chromium, nitrogen and copper elements give extremely high pitting‑resistance equivalent PREn value, far exceeding regular austenitic grades such as 316L and 904L. It performs reliably in hot seawater, concentrated brine, flue‑gas scrubber condensate and mixed oxidizing‑reducing acid environments. Widely processed into pump shafts, valve stems, agitator rods, heat‑exchanger component blanks and high‑strength corrosion‑resistant fasteners for seawater‑desalination, offshore‑marine, power‑plant FGD scrubber and heavy‑duty chemical‑processing industries.

Material Grade Characteristics – 254SMO (UNS S31254 / 1.4547)

• High‑alloy 6Mo super‑austenitic stainless steel, PREn ≥42.5 for severe chloride‑containing operating environments
• Ultra‑low carbon (C ≤0.02 %) minimizes intergranular‑sensitization risk after welding
• Combined Mo‑N‑Cu alloy system: molybdenum‑nitrogen improve pitting‑crevice resistance; copper enhances reducing‑acid tolerance
• Fully austenitic, non‑magnetic after solution annealing; maintains excellent impact toughness at cryogenic temperatures
• Excellent resistance to chloride‑induced stress‑corrosion‑cracking (SCC) in warm brine media
• Good weldability with matching filler materials; post‑weld solution‑annealing is recommended for maximum corrosion performance
• Solution‑annealed & water‑quenched delivery guarantees homogeneous austenite phase and low residual stress

Chemical Composition (Weight %)

表格

Mechanical Properties (Solution Annealed, ASTM A276 / A479)

表格

Related Material Grades

• Super‑Austenitic Stainless Steel: 254SMO(S31254), 904L(N08904), AL‑6XN(N08367)
• Duplex / Super Duplex: 2205(S32205), 2507(S32750), S32760(Zeron100)
• Conventional Austenitic Stainless Steel: 316L, 317L, 321, 347
• Nickel‑Base Alloys: Incoloy 825, Inconel 625, Hastelloy C276
• PH Stainless Steel: 17‑4PH,15‑5PH
• Alloy Steel:4140, F22, F91, A105

Key Advantages

1. Ultra‑High Chloride Corrosion ResistanceHigh PREn ≥42.5 value delivers outstanding pitting and crevice‑corrosion resistance for seawater, hot brine and chloride‑rich process media, outperforms 316L and 904L grades.
2. Mixed‑Acid Media Compatibility
   Copper alloy addition improves resistance to sulfuric‑phosphoric reducing‑acid environments, ideal for complex chemical‑process and flue‑gas‑desulfurization scrubber conditions.
3. Excellent Low‑Temperature Toughness
   Stable fully‑austenitic microstructure retains high impact toughness under cryogenic service, no brittle‑fracture risk for low‑temperature equipment.
4. Superior Anti‑SCC Performance
   Greatly improved chloride stress‑corrosion‑cracking resistance compared to ordinary 300‑series austenitic stainless steel for warm‑salt‑water service.
5. Versatile Fabrication Performance
   Good machinability in solution‑annealed condition, compatible with conventional welding processes; post‑weld solution annealing is recommended for maximum corrosion resistance.

Typical Applications

• Seawater Desalination: SWRO high‑pressure pump shafts, evaporator component blanks, brine‑handling rotary parts
• Power‑Plant FGD: Flue‑gas desulfurization scrubber agitator rods, condensate‑exposed pump‑valve components
• Offshore & Marine: Seawater‑injection equipment parts, marine‑platform corrosion‑resistant structural blanks
• Chemical‑Processing: Mixed‑acid reactor agitator shafts, heat‑exchanger bars, corrosive‑media circulating pump spindles
• Pulp & Paper Industry: Bleaching‑process equipment rotary components, high‑chloride‑process hardware blanks

Processing Service

We provide integrated hot‑rolling / forging / cold‑drawn round‑bar production, full custom CNC machining per customer CAD/PDF drawings:

• Fixed‑length cutting, facing, centering, external turning & chamfering
• Precision threading, spline machining, cylindrical grinding & surface polishing
• Technical consultation for super‑austenitic welding and post‑weld heat‑treatment specification
• Pickling, passivation anti‑corrosion surface finishing

We supply 254SMO S31254 super‑austenitic round‑bar blanks and custom‑machined components for desalination, power‑plant FGD, offshore and chemical‑industry global clients.

Quality Assurance

• 100% UT ultrasonic + eddy‑current inspection for internal segregation, inclusion and surface crack defects
• Full‑batch tensile, yield, elongation and Charpy impact mechanical testing for each heat lot
• Spectrometer full‑spectrum chemical‑composition verification per heat number
• Metallographic full‑austenite microstructure inspection to verify phase purity, no harmful precipitates
• High‑precision micrometer & CMM inspection for diameter, straightness and dimensional‑tolerance control

Mill Test Certificate EN 10204 3.1 can be issued and delivered together with shipment documents before delivery.

Packing & Delivery

Packing ‑ Inner: Independent anti‑rust plastic sleeve + waterproof film full wrap for bar‑surface scratch protection ‑ Outer: Reinforced fumigated wooden pallet with separation strips to avoid collision & bending deformation ‑ Custom heavy‑duty export packaging for extra‑long / large‑diameter bars available upon request

Lead Time
Normally 10‑45 working days after receiving advance payment. Exact lead time depends on bar diameter, length, order quantity and custom machining demands.

Request Custom Quotation

Please specify grade, bar dimension, drawings and whether you require raw bar blank or fully‑machined finished parts. Our super‑austenitic‑steel metallurgy team will provide competitive factory price within 24 hours. Free corrosive‑medium material‑matching technical consultation!