Related Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
ASTM A1082/A1082M Grade S39277 | AL-6XN Super Austenitic Steel
Premium 6-moly super austenitic alloy for extreme corrosion environments
Grade S39277 (UNS S39277) is a premium super austenitic stainless steel, commonly known as AL-6XN or ASTM A1082/A1082M F62, featuring 6% molybdenum, 24% nickel, and 21% chromium with nitrogen additions to deliver exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking in highly aggressive chloride and acidic environments. With a PREN value exceeding 51, S39277 outperforms standard austenitic grades and competes with nickel-based alloys in applications such as flue gas desulfurization systems, phosphoric acid production, sulfuric acid processing, seawater cooling systems, and offshore oil and gas production where localized corrosion is critical. This super austenitic grade maintains excellent mechanical properties and fabricability at temperatures up to 750°F (400°C) and offers superior resistance to chloride-induced stress corrosion cracking compared to conventional 316L stainless steel.
ASTM A1082/A1082M Grade S39277 Chemical Composition
| Grades | UNS Designation | Type | C | Mn | P | S | Si | Cr | Ni | Mo | N | Other ElementsB |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ASTM A1082/A1082M Super Austenitic Stainless Steel Grades | S39277 | . . . | 0.025 | 0.80 | 0.025 | 0.002 | 0.80 | 24.0-26.0 | 6.5-8.0 | 3.0-4.0 | 0.23-.033 | Cu 1.20-2.00,W 0.80-1.20 |
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Frequently Asked Questions
What is AL-6XN (S39277)?
AL-6XN (S39277) is a stainless steel grade covered under ASTM A1082/A1082M for high-strength bolting in special-purpose applications such as pressure vessels. UNS designation S39277. Available as bolts, studs, screws and nuts manufactured by TorqBolt for global oil/gas/nuclear/power/marine sectors.
What are the mechanical properties of AL-6XN (S39277) per ASTM A1082?
Mechanical property requirements for S39277 are defined in ASTM A1082 Table 2 (PH grade solution treatment) or Table 4 (duplex annealed condition). Properties vary by treatment condition - refer to the bolting specification for the H-condition (PH) or annealed yield/tensile/elongation/hardness requirements applicable to your order.
Is AL-6XN (S39277) suitable for sour service (NACE MR0175)?
Refer to NACE MR0175 / ISO 15156 Tables A.16-A.19. Most A1082 duplex grades are permitted at ≤28 HRC; PH grades require condition-specific qualification (typically H1150 for 17-4 PH at 28 HRC). TorqBolt supplies sour-service certified product on request with full PMI + hardness traceability.
What ASME / ISO dimensional standards can AL-6XN (S39277) be supplied to?
This grade is available across the full ASME and ISO bolting dimensional standards covered on this site - ASME B18.2.1 (hex bolts, hex cap screws, lag screws), B18.2.2 (hex nuts, square nuts, lock nuts), B18.3 (socket head cap screws), B18.31.2 (clamping studs), B16.5 (flange stud bolts), ISO 4032 / 4033 / 4035 (metric nuts), and metric B18.2.3.xM / B18.2.4.xM series.
References & Standards
- ASTM A1082 / A1082M - Standard Specification for High-Strength Precipitation-Hardening and Duplex Stainless Steel Bolting for Special-Purpose Applications (current edition 2016, active)
- ASTM A962 / A962M - General Requirements for Special-Purpose Bolting Materials
- ASTM A370 - Mechanical Testing of Steel Products
- NACE MR0175 / ISO 15156 - Sour-service hardness limits for petroleum & natural gas industries
- ASME B18 series - Dimensional standards for bolts, screws, nuts, studs
- ISO 4032 / 4033 / 4035 - Metric hexagon nut dimensional standards
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