AL‑6XN Plates | UNS N08367 Super Austenitic Plates for Chemical, Oil & Gas, Marine, Pharma & Power
Table of Contents:
A coastal pharma and specialty‑chemicals complex had already upgraded its critical CIP tanks and seawater‑cooled exchangers from 316L to duplex stainless, yet every turnaround the inspection reports came back with the same red flags: deep pitting under deposits in caustic–chloride solutions, crevice attack in gasket grooves and severe under‑deposit corrosion where hot brine sat stagnant. When the integrity and procurement teams rebuilt the worst‑affected reactor covers, tube sheets and distribution headers in AL‑6XN Plates (UNS N08367), they moved to a 6‑moly superaustenitic alloy with about 24% nickel, 20–22% chromium, 6–7% molybdenum and around 0.18–0.25% nitrogen that delivers a PREN of roughly 47–48, typical yield strength around 393 MPa, tensile strength around 770 MPa, elongation about 44%; subsequent corrosion audits reported essentially clean surfaces where 316L and duplex had pitted badly, even under long periods of seawater stagnation and chlorination.
AL‑6XN is a low‑carbon, high‑purity, nitrogen‑bearing superaustenitic stainless steel developed for highly aggressive chloride‑containing environments where conventional austenitic alloys fail. The alloy is designated UNS N08367 and is described as containing high nickel (around 24%), chromium (about 20.5%), molybdenum (about 6.2%) and nitrogen (around 0.22%), giving it outstanding resistance to pitting, crevice corrosion and stress‑corrosion cracking in chlorides and seawater, with a calculated PREN of about 47.6. Product data list modulus of elasticity around 195 GPa and mechanical properties in plate and strip with typical yield strength 57 ksi (≈393 MPa), tensile strength 112 ksi (≈770 MPa) and elongation about 44% in 2 in.
For procurement heads, corrosion engineers, fabricators, OEM manufacturers and hardware or industrial supply stores in the chemical, oil & gas, marine, pharma and power‑generation industries, AL‑6XN plates provide a way to extend asset life where 316L, 317L, 904L or duplex grades are no longer sufficient but full nickel‑base alloys seem too costly. Technical references describe AL‑6XN as having excellent resistance to general corrosion, pitting and crevice corrosion in chloride solutions and practical immunity to stress‑corrosion cracking in sodium chloride environments, with ASME allowable design stress around 26.2 ksi (≈181 MPa) at 200 °F significantly higher than many standard austenitic stainless steels. Field experience notes successful seawater service, resistance to erosion at high velocities and widespread use in desalination, offshore drilling and power‑plant cooling systems where high strength and chloride resistance are required.
Aurico Alloys LLP can support these duties as an affordable, authentic AL‑6XN Plates supplier, manufacturer and stockist in India with export capability abroad, providing plate produced to UNS N08367 chemistry ranges under ASTM B688 / ASME SB‑688 and related standards with EN 10204 certification for EPC, OEM and MRO customers.
High-quality AL-6XN Plates ready for industrial use.
Specification Overview
| Supplier & Role | Aurico Alloys LLP – AL‑6XN Plates supplier, stockist, exporter in India to abroad |
|---|---|
| Alloy Description | Superaustenitic stainless steel with high Ni, Cr, Mo and N for aggressive chloride and seawater service |
| UNS / Alloy Name | UNS N08367, commonly referred to as AL‑6XN or Alloy 25‑6HN |
| Main Plate Standards | ASTM B688 / ASME SB‑688 for UNS N08367 plate, sheet and strip; also covered as a corrosion‑resistant plate in ASTM A240 contexts |
| Thickness Range | 4.75 mm – 150 mm |
| Pitting Resistance (PREN) | ≈47.6 based on composition, significantly higher than conventional austenitic stainless steels |
UNS & Equivalent Grades
| Property | Value |
|---|---|
| UNS number | N08367 |
| Density | 8.06 g/cm3 |
| Melting range | 1320-1400 °C |
| Modulus of elasticity | 195 GPa |
| Shear modulus | 74 GPa |
| Poisson's ratio | 0.31 |
| Thermal conductivity (20-100 °C) | 14.1 W/m·K |
| Coefficient of expansion (20-100 °C) | 14.2 µm/m·°C |
| Specific heat | 500 J/kg·K |
| Electrical resistivity | 89.0 µΩ·cm |
| Magnetic permeability (at 200 H - annealed and 65% cold-worked plate) | 1.0028 |
| Scaling temperature | 1030 °C |
| Plate, sheet and strip specification | ASTM B688 |
Identifiers and physical constants for AL-6XN. A dash means no such designation is published for this grade.
Stock & Product Availability
As an AL‑6XN Plates stockist, Aurico Alloys LLP can supply plate and sheet in thicknesses suitable for seawater RO frames, high‑chloride heat‑exchanger plates, tube sheets, channel covers, chemical reactor and scrubber shells and structural plates in chemical, oil & gas, marine, pharma and power projects, within typical ASTM B688 thickness and width ranges.
Chemical Composition
| Element | Min (%) | Max (%) |
|---|---|---|
| Carbon (C) | — | 0.03 |
| Manganese (Mn) | — | 2.00 |
| Phosphorus (P) | — | 0.040 |
| Sulfur (S) | — | 0.030 |
| Silicon (Si) | — | 1.00 |
| Chromium (Cr) | 20.00 | 22.00 |
| Nickel (Ni) | 23.50 | 25.50 |
| Molybdenum (Mo) | 6.00 | 7.00 |
| Nitrogen (N) | 0.18 | 0.25 |
| Copper (Cu) | — | 0.75 |
| Iron (Fe) | — | Balance |
Composition limits for AL-6XN. These are specification limits for the grade, not measured values for a lot; the mill test certificate supplied with your order states the actual analysis.
Mechanical & Physical Properties
| Property (Room Temperature, Typical Plate) | Typical Value – AL‑6XN |
|---|---|
| Ultimate Tensile Strength | ≈112 ksi (≈770 MPa) |
| Yield Strength (0.2% offset) | ≈57 ksi (≈393 MPa) |
| Elongation in 2 in (51 mm) | ≈44% |
| Hardness | ≈89 HRB in typical data |
| Modulus of Elasticity | ≈28.3 × 10⁶ psi (≈195 GPa) |
| Thermal Conductivity (≈20–100 °C) | ≈14.1 W/(m·K) in representative data |
| PREN | ≈47.6, indicating very high pitting resistance |
Applications & Benefits
- Chemical & Oil & Gas: AL‑6XN plates are used in chemical reactors, heat‑exchanger plates, piping, scrubbers and manifolds handling chloride‑containing solutions, acid chlorides and mixed salts, where their high Ni–Cr–Mo–N content provides excellent resistance to pitting, crevice corrosion and SCC compared with 316L and duplex steels.
- Marine & Power: In seawater RO plants, coastal power cooling systems and offshore topside equipment, AL‑6XN is highlighted as a seawater‑resistant alloy with proven performance and resistance to crevice corrosion in seawater even at high temperature, under prolonged stagnation and with chlorination, making it suitable for tube sheets, headers and plates exposed to severe chloride service.
- Pharma & Food: Processors adopt AL‑6XN plate in hygienic piping, CIP systems and high‑chloride wash or brine environments where both sanitary finish and resistance to chloride pitting and SCC are required, benefiting from the alloy’s formability and weldability.
FAQ & Search Trends
Global Export Destinations
We ship worldwide from Mumbai. See every destination we export to on our export markets page.
Domestic Supply Network
We deliver across India from our Mumbai stockyard. See every city we supply on our supply locations page.
Conclusion
AL‑6XN Plates from Aurico Alloys LLP, supplied to UNS N08367 chemistry ranges under ASTM B688 and related specifications, give chemical, oil & gas, marine, pharma and power‑generation users a superaustenitic plate option that combines high strength with exceptional resistance to chloride pitting, crevice corrosion and stress‑corrosion cracking in seawater and aggressive process fluids are your most critical chloride‑exposed and seawater‑cooled assets still relying on lower‑alloy materials instead of optimised AL‑6XN plates?