Super Austenitic Steel

Super austenitic stainless steel plates belong to a family of high-molybdenum, high-nickel austenitic alloys designed for severe corrosion service. These 6Mo grades utilise a 6% molybdenum minimum to bridge the performance gap between standard 316L and high-corrosion alloys. The high concentration of chromium and nickel provides the necessary structural framework for demanding applications. Significantly, the incorporation of nitrogen into grades such as 254 SMO enhances the Pitting Resistance Equivalent Number (PREN) beyond 40. The precise chemical proportions determine the metal's endurance and reliability under intense operational stress.

Super austenitic plates offer tensile strengths ranging from 490 MPa to 650 MPa. Ideal for offshore, chemical, and desalination plants, these products meet

Sachiya Steel International is a manufacturer, supplier, stockist, and exporter of super austenitic plates since the year 2005. We operate from Mumbai, India, with a ready-to-ship inventory of 1,500 to 2,000 metric tons across multiple grades and thicknesses. ISO 9001, ISO 14001, and ISO 45001 certifications. Every shipment includes full traceability and mill certificates. Custom sizes and shapes are always available upon your specific request.

Our high-quality plates fully comply with ASTM A240 / ASME SA-240, ASTM B625 / ASME SB-625, and ASTM B688 / ASME SB-688 international standards. In hot-rolled, cold-rolled, and solution-annealed conditions, we offer 254 SMO, AL-6XN, 904L, Alloy 926, Alloy 20, and 654 SMO plates. In order to satisfy your pressing project needs, all materials are prepared for immediate dispatch.

This page covers:

Specifications
Price Range
Super Austenitic Plate Grades
Available Forms
Industrial Applications
Comparison Materials
Shipping & Packaging
Frequently Asked Questions

Specifications for Super Austenitic Plates

Refer to the following technical datasheet for the manufacturing specifications and available configurations for Super Austenitic Stainless Steel Plates. These high-alloy materials are designed for extreme corrosion resistance in chloride-rich and acidic environments.

Super Austenitic Stainless Steel Plate Specifications

Property	Specification / Details
Standards	ASTM A240, ASME SA240
Common Grades	904L, 254 SMO (UNS S31254), AL-6XN (UNS N08367), Alloy 926
Thickness	3.0 mm to 50 mm (Standard), up to 100 mm (Custom)
Width	1000 mm, 1250 mm, 1500 mm, 2000 mm, 2500 mm
Length	2000 mm to 12000 mm
PREN Value	> 40 (Pitting Resistance Equivalent Number)
Available Forms	Cut-to-size, Coils, Foils, Shims, Perforated, Chequered
Surface Finishes	No. 1 (HRAP), 2B, BA, No. 4, No. 8 Mirror, Satin
Edge Condition	Mill Edge, Slit Edge, Deburred, V-Beveled
Value Added Services	Laser Cutting, Plasma Profiling, Waterjet Cutting, Polishing

Available Sizes of Super Austenitic Plates

We stock super austenitic plates in a standard range of dimensions. Custom cut-to-size is available on request.

Thicker plates (above 50 mm) require careful solution annealing due to slower cooling rates, which increase sigma phase precipitation risk in the 875-1025°C range.

Dimension Parameter	Range / Specification
Thickness	1.5 mm to 150 mm
Standard Widths	1000 mm, 1250 mm, 1500 mm, 2000 mm, 2500 mm
Standard Lengths	2000 mm, 3000 mm, 6000 mm, up to 12000 mm
Custom Processing	Precision Cut-to-Size (Plasma, Waterjet, Laser)
Critical Annealing Zone	875°C – 1025°C (Risk of Sigma Phase)
Special Requirement	Solution annealing for plates > 50 mm thickness

Super Austenitic Plate Price Range

High molybdenum and nickel content make super austenitic plates expensive. In India, austenitic plates cost ₹200–₹350/kg, while in the USA, prices range from $3.50–$5.50/kg. Grades like 254 SMO cost 3–5 times more than others. Due to lower molybdenum, they cost less. Pricing depends on grade, thickness, and market rates.

Super Austenitic Plate Grades

Super austenitic plates are available in 2 main grades, split between 6Mo variants and other high-alloy options

254 SMO (S31254)

254 SMO plates are manufactured per ASTM A240 / ASME SA-240 with 6.0-6.5% molybdenum. The PREN exceeds 42.5, making this grade suitable for seawater systems, chemical processing, and flue gas desulphurisation.

Alloy 20 (N08020)

This grade offers the highest nickel content in the super austenitic family at 32.0-38.0%. Copper at 3.0-4.0% gives Alloy 20 its strong sulphuric acid resistance per ASTM A240 / ASME SA-240.

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Available Forms of Super Austenitic Plates

Super austenitic stainless steel plates are supplied in several forms and finishes to match different application requirements:

Hot Rolled Plates (standard production form)
Cold Rolled Sheets (thinner gauges, tighter dimensional tolerances)
Solution Annealed and Pickled (standard delivery condition)
Clad Plates (super austenitic layer on carbon steel substrate for cost savings in thick sections)
Surface finishes: No. 1, 2B, 2D, #4 Polish, BA

Industrial Applications of Super Austenitic Plates

Super austenitic plates find use across 4 primary industrial sectors where standard austenitic grades like 316L cannot withstand the corrosion environment.

Offshore & Marine

Super austenitic plates handle seawater cooling systems, subsea equipment, and marine heat exchangers where chloride pitting is a constant risk.

Chemical Processing

Super austenitic plates resist extreme corrosion in phosphoric acid production, flue gas desulphurisation, and high-chloride chemical processing environments.

Desalination & Water Treatment

Super Austenitic plates serve reverse osmosis pressure vessels, brine heaters, and evaporator tubes in thermal desalination plants.

Pulp & Paper

Chlorine dioxide bleaching stages in pulp mills use super austenitic plates for digesters, washers, and bleach plant piping supports.

Shipping & Packaging

Heavy-duty wooden boxes Packing

Export Packaging Standard

We strictly follow seaworthy export handling standards to protect super austenitic plates from transit damage, moisture ingress, and surface contamination during long-distance dispatch.

Heavy-duty wooden boxes with moisture barrier lining
HDPE stretch film wrapping on all bundles
Edge and corner protection with plastic padding
Silica gel desiccants to minimize moisture exposure
ISPM-15 fumigated wooden packaging for export

Plate Bundle Yard Staging

Plate Bundle Edge Protection

Wrapped Export-Ready Bundles

We Export Worldwide

Sachiya Steel International supplies stainless steel products to major industrial markets across North America, Europe, the Middle East, Asia and Africa with export-ready documentation and logistics support.

USA
Canada

Frequently Asked Questions:

What ASTM standards cover Super Austenitic Plates? +

Super austenitic plates are covered by ASTM A240 / ASME SA-240(254 SMO, Alloy 20).

What is the difference between 254 SMO and AL-6XN Plates? +

Both are 6Mo super austenitic plates with similar corrosion resistance. 254 SMO (S31254) is specified under ASTM A240, while AL-6XN (N08367) falls under ASTM B688. They differ slightly in nickel content and minor alloying elements.

How does sigma phase affect Super Austenitic Plate fabrication? +

Sigma phase precipitates in super austenitic plates occur between the temperature range of 875-1025 °C, with the most rapid production occurring near 925 °C. Appropriate solution annealing following hot working is essential. Thicker plates carry greater risk due to slower cooling rates.

What thickness range is available for Super Austenitic Plates? +

Super austenitic plates are available from 1.5 mm to 150 mm thickness, with widths up to 2500 mm and lengths up to 12000 mm. Custom dimensions are available on request.

Is 904L Plate considered Super Austenitic? +

904L (N08904) is classified as super austenitic due to its high nickel (23-28%) and molybdenum (4-5%) content. Its molybdenum level is below the 6% threshold of core 6Mo grades like 254 SMO, so it's sometimes considered a borderline member of the family.

What is the PREN of Super Austenitic Plate grades? +

PREN values for super austenitic plates are AL-6XN 45 or above, 254 SMO 42.5 or above, Alloy 926 40 or above, and 904L 34 or above. Higher PREN indicates greater pitting and crevice corrosion resistance.

What is the price range for Super Austenitic Plates? +

Hyperaustenitic plates are expensive because they have a lot of molybdenum and nickel in them. In the US, austenitic plates cost $3.50 to $5.50/kg, but in India, they cost ₹200 to 350/kg. It costs three to five times more for grades like 254 SMO. Low molybdenum makes it less expensive. The price is based on grade, width, and market rates.

Where can you buy Super Austenitic Plates? +

Sachiya Steel International supplies super austenitic plates in all major grades with mill test certificates, full material traceability, and compliance with ASTM A240, B625, and B688 specifications. We ship worldwide from our Mumbai warehouse.