Kanakratna Steelage Private Limited

Modern industries such as marine, chemical processing, offshore oil & gas, desalination, pulp & paper, and power generation face the constant challenge of operating in highly corrosive environments. Materials exposed to chloride-rich seawater, acidic solutions, and high-pressure systems require exceptional corrosion resistance, strength, and durability.

While conventional stainless steels like 316L or even Duplex 2205 provide good corrosion resistance, they fail in extremely harsh conditions. To meet these demands, super-austenitic stainless steels like SMO 254 (UNS S31254) were developed.

SMO 254 Plate is a flat-rolled product with greater thickness compared to sheet material, typically above 5 mm up to 100 mm or more, designed for pressure vessels, heat exchangers, tanks, and marine structures. It is widely recognized for its exceptional pitting and crevice corrosion resistance, superior mechanical strength, and long service life in critical applications.

• Tensile Strength: ≥ 650 MPa

• Yield Strength (0.2% offset): ≥ 300 MPa

• Elongation: ~35%

• Hardness: ≤ 95 HRB

• Impact Toughness: Excellent, even at cryogenic temperatures

• Density: 8.0 g/cm³

• Melting Range: 1320 – 1390 °C

• Thermal Conductivity: 12 W/m·K

• Electrical Resistivity: ~0.92 μΩ·m

• Non-magnetic in annealed condition

• Tensile and Hardness Tests

• Impact Testing – Charpy V-notch at room and low temperatures

• Corrosion Testing – ASTM G48 for pitting resistance

• Ultrasonic Testing – To check internal defects

• Positive Material Identification (PMI) – Ensures correct grade supplied

Additional Information:

• Production Capacity: IN TONS
• Delivery Time: READY STOCK
• Packaging Details: The packaging of the product is done using an effective method of packaging. It all includes- • Shrink-wrapping • Bubble wrapping • Carton boxes • Wooden crates/pallets/boxes

In industries where corrosion resistance, strength, and reliability are non-negotiable, stainless steel alloys play a central role. However, not all stainless steels can withstand harsh chloride-rich environments, acidic solutions, and high-stress conditions.

This is where SMO 254 Sheet (UNS S31254) stands out. Also known as 6Mo stainless steel or Alloy 254, SMO 254 is a super-austenitic stainless steel developed to offer exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking, especially in seawater, desalination, and chemical process environments.

SMO 254 Sheets are widely used in industries such as offshore oil & gas, marine, pulp & paper, chemical processing, desalination, and food processing. Its high molybdenum content (~6%), along with nitrogen and chromium additions, gives it a Pitting Resistance Equivalent Number (PREN) > 42, surpassing even duplex stainless steels.

This article provides a complete 4000-word guide on SMO 254 Sheets, covering composition, metallurgy, properties, manufacturing, standards, applications, advantages, limitations, and market trends.

• Tensile Strength: ≥ 650 MPa

• Yield Strength (0.2% proof): ≥ 300 MPa

• Elongation: ~35%

• Hardness: ~95 HRB (≤ 32 HRC)

• Impact Toughness: Excellent, even at sub-zero temperatures

• Density: 8.0 g/cm³

• Melting Range: 1320 – 1390 °C

• Thermal Conductivity: 12 W/m·K (lower than duplex steels)

• Electrical Resistivity: ~0.92 μΩ·m

• Magnetic Permeability: Non-magnetic

• Mechanical Testing – Tensile, hardness, impact

• Corrosion Testing – ASTM G48 pitting tests

• Non-Destructive Testing – Ultrasonic, eddy current, X-ray

• Positive Material Identification (PMI) – To ensure correct alloy

• Surface Finish Testing – Roughness and micro-cleanliness checks

Additional Information:

• Production Capacity: AS PER CLIENT REQUIREMENT
• Delivery Time: 3 TO 4 DAYS
• Packaging Details: The packaging of the product is done using an effective method of packaging. It all includes- • Shrink-wrapping • Bubble wrapping • Carton boxes • Wooden crates/pallets/boxes

SMO 254 (UNS S31254) is a high-alloy austenitic stainless steel developed for maximum resistance to pitting and crevice corrosion in aggressive chloride-bearing environments. Due to its superior corrosion resistance and mechanical strength, SMO 254 round bars are widely used in industries like desalination, offshore oil and gas, chemical processing, pulp and paper, and marine engineering.

SMO 254 belongs to a special class of super-austenitic stainless steels, characterized by high levels of molybdenum, nitrogen, and chromium, which enable the alloy to perform in highly corrosive environments that would destroy conventional stainless steels like 316L. This document provides a comprehensive technical analysis of SMO 254 round bars, covering their composition, physical and mechanical properties, corrosion resistance behavior, processing techniques, and performance across industrial sectors.

The exceptional performance of SMO 254 is due to its carefully engineered chemical composition, which includes significantly higher amounts of chromium, molybdenum, and nitrogen compared to standard stainless steels.

This high-alloy content gives SMO 254 an extremely high Pitting Resistance Equivalent Number (PREN) of >42, which is well above that of 316L or even duplex stainless steels.

SMO 254 is fully austenitic, stabilized by high Ni, Cr, Cu, and N levels. There is no sensitization risk unless exposed to 600–1000 °C for prolonged periods. Even then, Strath's ASTM A262 practice E tests show no intergranular corrosion, largely thanks to its low C and intentional use of nitrogen. Its corrosion resistance relies on a clean, homogeneous structure without detrimental intermetallics.

Additional Information:

• Delivery Time: READY STOCK
• Packaging Details: The packaging of the product is done using an effective method of packaging. It all includes- • Shrink-wrapping • Bubble wrapping • Carton boxes • Wooden crates/pallets/boxes

SMO 254 Pipe (also known as Alloy 254, UNS S31254, or 6Mo stainless steel pipe) is a high-performance austenitic stainless steel pipe developed for service in aggressive chloride-bearing environments. It contains a very high level of molybdenum (6%), chromium (20%), and nitrogen, which makes it one of the most corrosion-resistant stainless steels available.

SMO 254 pipes are widely used in:

• Seawater handling systems

• Desalination plants

• Chemical processing industries

• Pulp & paper bleaching plants

• Oil & gas offshore structures

Its exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC) makes it an ideal replacement for more expensive nickel-based alloys (Alloy 625, Alloy 825) in many applications.

SMO 254 Pipes are produced according to international standards, ensuring global applicability.

• UNS S31254

• Werkstoff Nr. 1.4547

• EN 1.4547

• ASTM A312 / ASME SA312 – Seamless and welded austenitic stainless steel pipes.

• ASTM A790 / ASME SA790 – For duplex and super austenitic stainless steel pipes.

• ASTM A213 / ASME SA213 – Boiler and heat exchanger pipes.

• NACE MR0175 / ISO 15156 – For sour service in oil & gas environments.

Available product forms:

• Seamless Pipes

• Welded Pipes

• ERW (Electric Resistance Welded) Pipes

• EFW (Electric Fusion Welded) Pipes

• Custom Fabricated Pipes

• Density: 8.0 g/cm³

• Melting Range: 1320–1390 °C

• Thermal Conductivity: 12 W/m·K (at 100 °C)

• Specific Heat: 500 J/kg·K

• Electrical Resistivity: 0.92 µΩ·m

• Chemical Analysis (PMI, spectrometry).

• Mechanical Tests: Tensile, hardness, impact.

• NDT Methods: Ultrasonic, radiography, eddy current.

• Hydrostatic Testing – Ensures pressure resistance.

• Corrosion Testing: ASTM G48 (pitting resistance).

• Microstructure Analysis.

Additional Information:

• Production Capacity: IN TONS
• Delivery Time: READY STOCK
• Packaging Details: The packaging of the product is done using an effective method of packaging. It all includes- • Shrink-wrapping • Bubble wrapping • Carton boxes • Wooden crates/pallets/boxes

SMO 254 Round Bar, designated by the Unified Numbering System as UNS S31254, is a high-end austenitic stainless steel alloy developed for maximum resistance to pitting and crevice corrosion in aggressive chloride-bearing environments. It contains high levels of molybdenum, chromium, and nitrogen, providing outstanding strength and corrosion resistance unmatched by conventional austenitic grades such as 304 or 316.

This alloy is widely used in applications involving seawater, chemical processing, pulp and paper, and offshore oil and gas environments. The round bar form is essential for machined components like shafts, fasteners, pump parts, valves, and marine hardware.

The superior corrosion resistance of SMO 254 is largely attributed to its carefully balanced composition:

• Annealing: 1150°C – 1200°C

• Rapid cooling after annealing is essential to avoid sensitization.

• SMO 254 is not hardenable by heat treatment (non-magnetic in annealed condition).

• Diameter: 10 mm to 300 mm

• Length: Up to 6 meters (custom cut lengths available)

Additional Information:

• Item Code: UNSNO31254
• Production Capacity: 1000 TONS
• Delivery Time: 2-5 DAYS
• Packaging Details: The packaging of the product is done using an effective method of packaging. It all includes- • Shrink-wrapping • Bubble wrapping • Carton boxes • Wooden crates/pallets/boxes

SMO 254 (UNS S31254) is a super austenitic stainless steel alloy with a high content of molybdenum (6%), chromium (20%), and nickel (18%), along with nitrogen additions. It was originally developed for seawater and chloride-rich environments where conventional stainless steels such as 316L and duplex grades fail due to pitting, crevice corrosion, and stress corrosion cracking.

When fabricated into fittings—such as elbows, tees, reducers, couplings, and caps—SMO 254 demonstrates outstanding corrosion resistance, strength, and durability in aggressive chemical and marine service conditions.

This article provides an in-depth look at SMO 254 Fittings (UNS S31254), covering everything from chemical composition and properties to manufacturing processes, standards, applications, and global demand.

The chemical makeup of SMO 254 is what makes it uniquely resistant to pitting and crevice corrosion.

• Chemical Analysis – Spectro/OES

• Tensile & Hardness Testing

• Impact Testing (Charpy V-Notch)

• Corrosion Testing – ASTM G48

• Non-Destructive Testing – Ultrasonic, radiography, dye penetrant

• Dimensional & Hydrostatic Testing

Additional Information:

• Production Capacity: IN TONS
• Delivery Time: READY STOCK
• Packaging Details: The packaging of the product is done using an effective method of packaging. It all includes- • Shrink-wrapping • Bubble wrapping • Carton boxes • Wooden crates/pallets/boxes