COMPREHENSIVE TECHNICAL ANALYSIS AND DATASHEET OF ASTM A453 GRADE 660 (A286) FASTENING SYSTEMS

ASTM A453 Grade 660, universally known by its alloy designation A286, is a premium precipitation-hardening austenitic stainless steel. Designed explicitly for high-temperature service, this iron-nickel-chromium alloy delivers exceptional tensile strength, excellent creep resistance, and high oxidation resistance at elevated temperatures up to 1300°F (704°C).



Through a highly controlled solution annealing and aging (precipitation hardening) heat treatment process, Grade 660 achieves structural uniformity and high yield strengths without sacrificing ductility. It is the definitive fastening choice for extreme environments, serving as the backbone for gas turbine engineering, aerospace engine components, and severe-service petrochemical extraction infrastructure.

■ Product Overview & Specifications

ASTM A453 Grade 660 is manufactured in four distinct classes (A, B, C, and D), dictating specific heat treatments to achieve desired mechanical properties. Classes A and B are the most frequently specified for industrial heavy-duty bolting.











Material Classification

Precipitation-Hardening Austenitic Stainless Steel





UNS Designation

S66286 (Alloy A286)





Microstructure

Austenitic





Magnetic State

Non-Magnetic





Density

~7.92 g/cm³ (0.286 lb/in³)





Size Range

Metric: M6 to M100 | Imperial: 1/4\” to 4\”Custom forged oversized fasteners available upon request.





Thread Types

UNC, UNF, 8UN, Metric Coarse, Metric Fine (Rolled threads recommended for fatigue resistance)





Strengthening Method

Solution Annealing + Age Hardening (Precipitation)

■ Proprietary Datasheet Download (GATED)

Access professional-grade technical data for ASTM A453 Grade 660, including stress-rupture test charts, elevated temperature yield data, and gall-resistant installation parameters.





📄

ASTM A453 Grade 660 (A286) — Complete Technical Datasheet

Contains detailed stress-rupture thresholds (min 100 hours at 1200°F), Class A through D mechanical comparisons, and specific dry/lubricated installation values to prevent thread galling.

⬇ DOWNLOAD DATASHEET

■ MTC Integration Section

For aerospace and high-pressure applications, absolute metallurgical traceability is mandatory. Every lot of Grade 660 shipped by Ananka includes comprehensive certification.



EN 10204 Type 3.1: Includes actual chemical analysis, room-temperature mechanical testing, hardness mapping, and the mandatory high-temperature stress-rupture test results required by ASTM A453.

EN 10204 Type 3.2: For critical offshore or aerospace deployments, we facilitate independent third-party witness testing (e.g., DNV, Lloyds, TUV).







View Our Sample MTC:

Download ASTM A453 Grade 660 Sample MTC →

■ Chemical Composition (UNS S66286)

The addition of Titanium and Aluminum forms the intermetallic compounds necessary for precipitation hardening, while high Nickel and Chromium content provide exceptional corrosion and oxidation resistance.











Nickel (Ni)

Chromium (Cr)

Titanium (Ti)

Moly (Mo)

Manganese (Mn)

Silicon (Si)

Carbon (C)









24.0 – 27.0

13.5 – 16.0

1.90 – 2.35

1.00 – 1.50

2.00 Max

1.00 Max

0.08 Max









*Also contains Aluminum (0.35 Max), Vanadium (0.10-0.50), and trace Boron (0.001-0.010) to enhance high-temperature creep strength.

■ Mechanical Properties (By Class)

Grade 660 properties are determined by their specific solution treating and aging cycles. Class A and B share identical tensile strengths but undergo different solution treatments, affecting high-temperature ductility.











Property

Class A, B & C

Class D









Tensile Strength (Min)

130 ksi (895 MPa)

130 ksi (895 MPa)





Yield Strength (0.2% Offset, Min)

85 ksi (585 MPa)

105 ksi (725 MPa)





Elongation in 2\” (Min)

15%

15%





Reduction of Area (Min)

18%

18%





Hardness (Brinell)

248 to 341 HBW

248 to 341 HBW

■ Equivalent Grades & Designations

Standard / System

Designation







UNS DesignationS66286

Common Trade NameAlloy A286, A-286 Stainless

European EquivalentEN 1.4980 / X6NiCrTiMoVB25-15-2

Aerospace SpecsAMS 5731, AMS 5732, AMS 5737

■ Applications & Industries

A286 is utilized where extreme thermal stress would cause standard 300-series stainless steels or Cr-Mo alloys to rapidly degrade or suffer catastrophic creep failure.



Gas Turbines & Power Generation: Turbine engine bolting, superchargers, and high-temperature exhaust manifold fasteners.

Aerospace & Defense: Jet engine components, rocket motor housings, and afterburner structural bolting.

Offshore & Subsea: High-pressure, high-temperature (HPHT) subsea wellhead equipment and severe-corrosion environments.

Automotive: High-performance exhaust systems and racing engine components.

■ Compatible Fastener Assemblies

Grade 660 studs and bolts are typically paired with nuts of the exact same metallurgical composition to prevent galvanic corrosion and ensure identical thermal expansion rates during extreme heat cycles.











Fastener Type

Recommended Mating Component









ASTM A453 Grade 660 Stud Bolts

ASTM A453 Grade 660 Heavy Hex Nuts





ASTM A453 Grade 660 Hex Bolts

ASTM A453 Grade 660 Standard / Heavy Hex Nuts

■ Torque & Installation Guidelines (Galling Prevention)

Like all austenitic stainless steels, Grade 660 is susceptible to thread galling (cold welding) under high friction. It is critical to use a high-quality nickel or molybdenum-disulfide (MoS2) based anti-seize compound during installation.











Nominal Diameter

Threads Per Inch (UNC)

Target Torque — Lubricated (MoS2) (ft-lbs)







1/2\”1345 – 55

5/8\”1190 – 110

3/4\”10150 – 180

1\”8380 – 420











Galling Warning: Never assemble Grade 660 fasteners dry. Always apply anti-seize paste to the threads and the nut bearing surface. Utilize slow, continuous tightening speeds; do not use high-speed impact wrenches.

■ Why Choose Ananka Group?

Ananka Group delivers precision-engineered A286 fastening solutions capable of surviving the world\’s most demanding thermal and corrosive environments.



Precision Thread Rolling: Threads are rolled rather than cut whenever possible, significantly increasing fatigue resistance in cyclic high-temperature applications.

Mandatory Stress-Rupture Testing: Full compliance with ASTM A453 stress-rupture testing requirements (min 100 hrs at 1200°F) to guarantee high-temperature stability.

Custom Machining: CNC machining capabilities for specialized aerospace profiles, 12-point bolts, and custom socket head cap screws in A286.

Certifications: ISO 9001:2015, ISO 14001:2015, and strict adherence to API and ASME bolting protocols.

■ Frequently Asked Questions

1. What is the difference between Class A and Class D in Grade 660?

The primary difference lies in the yield strength achieved through variations in the heat treatment process. Class A has a minimum yield strength of 85 ksi (585 MPa), while Class D undergoes a more aggressive aging cycle to reach a higher minimum yield strength of 105 ksi (725 MPa).

2. Is Grade 660 (A286) magnetic?

No. Because its base microstructure is fully austenitic, Alloy A286 remains completely non-magnetic, even after aggressive cold working or aging.

3. How does A286 compare to standard 316 Stainless Steel?

While both are austenitic, 316 stainless is primarily used for ambient or moderately warm corrosive environments. Grade 660 (A286) is heavily alloyed with Titanium, Aluminum, and Vanadium to allow for precipitation hardening, making it roughly twice as strong as 316 and capable of maintaining structural integrity at temperatures up to 1300°F (704°C), where 316 would rapidly fail.

4. Can Grade 660 be used in sub-zero cryogenic applications?

Yes. Although famous for its high-temperature performance, A286 also retains excellent toughness, ductility, and strength at cryogenic temperatures, making it highly versatile for aerospace applications that experience extreme thermal cycling.













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