A286 Lock Nuts
RAYCHIN SPECIALTY METALS FASTENERS: BOLTS, NUTS, SCREWS, WASHERS, STUDS, THREADED RODS, U-BOLT, J-BOLTS
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A286 / Alloy 660 for excellent high temperature oxidation resistance
Excellent high temperature oxidation resistance to 1300°F / 700°C
Maintains high strength at elevated temperatures
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RAYCHIN LIMITED
Specialist in A286 Lock Nuts · All-Metal · Nylon Insert · Prevailing Torque · Aerospace · CustomA286 Lock Nuts: All-Metal, Nylon Insert, Prevailing Torque, Aerospace & Custom Configurations
RAYCHIN LIMITED is a recognized expert in A286 lock nuts — from A286 all-metal lock nuts, A286 nylon insert lock nuts, A286 prevailing torque nuts, A286 aerospace lock nuts, A286 self-locking nuts to custom non-standard lock nut configurations. A286 (UNS S66286) is an iron-nickel-chromium superalloy strengthened by precipitation hardening. Also designated as Alloy 660, it maintains exceptional strength and oxidation resistance up to 700°C (1292°F), making it the preferred material for high-temperature lock nut applications in gas turbines, jet engines, and aerospace assemblies. Lock nuts provide vibration-resistant fastening through all-metal deformation (flexloc, stover styles) or polymer inserts. Our portfolio includes lock nuts manufactured to NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN and KS standards. Engineered for extreme environments where vibration resistance, high-temperature strength, and corrosion resistance are critical. A286 lock nuts are available in solution annealed and aged conditions with full traceability.
Complete Range of A286 Lock Nuts
A286 All-Metal Lock Nuts (Flexloc Style)
A286 all-metal lock nuts featuring a segmented collar that creates six "locking fingers" that act as a spring. This flexloc style design provides prevailing torque without the need for a separate locking element. Manufactured to DIN 980, ISO 7042, and ASME B18.16.6 specifications. Suitable for high-temperature applications up to 700°C where nylon inserts cannot be used. Available in hex, heavy hex, flange, and 12-point configurations. Reusable design with consistent prevailing torque performance. As the nut is all-metal, it is best for high temperature or corrosive applications and is certified to 15 cycles of prevailing torque – which is military standard.
A286 Nylon Insert Lock Nuts
A286 nylon insert lock nuts (Nylok type) with non-metallic locking element for vibration-resistant assemblies at temperatures up to 176°C (350°F). Manufactured to DIN 985, ISO 7040, and NASM 25027. Various polymers inserts available (Nylon, Vespel, PVDF) for higher temperature or corrosive applications. Excellent reusability – can reliably be re-used 15 times. Eliminates galling and cold-welding common with superalloys. Available in all standard thread sizes from #00 to 4" (M2 to M100). The A286 body provides exceptional high-temperature strength where the polymer insert temperature rating is not exceeded.
A286 Aerospace Lock Nuts
A286 aerospace lock nuts manufactured to NAS, AN, and MS specifications including NASM 21042 (12-point), NASM 21209 (hex), MS 21042, MS 21045, MS 21046, and AN 316. Designed for critical aerospace applications requiring vibration resistance and high-temperature strength up to 700°C. Available in all-metal self-locking configurations with optional silver plating per AMS 2410 for anti-galling. These are the most reliable all-metal self-locking nuts, ideal for gas turbine engines, exhaust systems, and aircraft structural applications.
A286 Prevailing Torque Lock Nuts
A286 prevailing torque lock nuts featuring top-lock or center-lock deformed thread designs, including stover and elliptical styles. Manufactured to IFI 100/107 and ASME B18.16.6 standards. Though these styles are often a cheaper initial cost, they are less reliable than the flexloc style. Consistent locking torque through multiple installation cycles. Ideal for applications where vibration and thermal cycling are present in high-temperature environments. Available in fine and coarse thread series.
A286 Flange Lock Nuts
A286 flange lock nuts with integrated washer face for improved bearing surface and locking action. Available with serrated flange or non-serrated flange. Manufactured to DIN 6926, ISO 7043, and ASME B18.16.6. The flange distributes clamping load and provides vibration resistance. Ideal for gas turbines, aerospace structures, and high-temperature equipment requiring both high-temperature strength and locking capability. Serrated flange versions provide additional locking action by biting into the bearing surface.
Custom & Specialty A286 Lock Nuts
Need a special thread size, unusual locking element, or custom configuration for your high-temperature application? RAYCHIN engineers work with you to produce custom A286 lock nuts to your drawing. Expert heat treatment (solution annealed at 982°C followed by precipitation hardening at 718°C for 16 hours) precisely controlled for each batch. Manufactured to NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN, KS standards. Special locking features and coatings available, including 12-point configurations.
Lock Nut Types & Applications for A286
Flexloc All-Metal Lock Nuts
Segmented collar creates six locking fingers. The most reliable all-metal self-locking nut. Can be used at high temperatures up to 700°C. Certified to 15 cycles of prevailing torque (military standard).
Nylon Insert Lock Nuts
Overall the most reliable locknut, with the only limitation of application temperature (<350°F). Excellent reusability (15 cycles). Eliminates galling and cold-welding.
Stover & Elliptical Lock Nuts
Deformed thread designs provide prevailing torque. Lower initial cost but less reliable than flexloc style with fewer prevailing torque cycles.
12-Point Lock Nuts
Available in both all-metal and polymer insert configurations. Designed for high-torque applications requiring compact envelope and superior high-temperature strength.
Manufacturing Standards for A286 Lock Nuts
RAYCHIN LIMITED manufactures A286 lock nuts to the following national and international standards, ensuring full compliance for projects worldwide. Both standard and non-standard custom configurations are available.
International Standards & Global Designations for A286 Lock Nuts
To serve clients worldwide, RAYCHIN LIMITED manufactures A286 lock nuts from material conforming to the following national and international specifications. This ensures full compliance for projects in the Americas, Europe, Asia, and the Middle East.
UNS S66286 Alloy 660 ASTM A453 AMS 5732 AMS 5737 NACE MR0175 1.4980 DIN 980 ISO 7042
Chemical Composition (Weight %) – A286 Superalloy (UNS S66286 / 1.4980)
Our A286 lock nuts are produced from melts that strictly conform to the limits below per ASTM A453 / AMS 5731. The high nickel and chromium content provide excellent oxidation resistance, while titanium and aluminum enable precipitation hardening through gamma-prime (γ') phase formation. Molybdenum and vanadium contribute to solid solution strengthening, and boron enhances creep resistance.
Expert note: The combination of titanium and aluminum promotes the formation of Ni₃(Al,Ti) gamma-prime precipitates during aging, which provide A286 with its exceptional high-temperature strength. The addition of boron (0.001-0.010%) significantly improves creep resistance by strengthening grain boundaries. With nickel content of 24-27%, A286 offers excellent resistance to chloride stress corrosion cracking and maintains a stable austenitic structure from cryogenic temperatures up to 700°C.
Complete Mechanical Properties of A286 Lock Nuts (per ASTM A453)
A286 lock nuts are supplied in the solution annealed and precipitation hardened condition (982°C solution treat + 718°C age for 16 hours). ASTM A453 defines multiple classes for different strength levels and size ranges. The data below represent minimum requirements per ASTM A453/A453M. Lock nuts are proof load tested to ensure compatibility with mating bolts.
Tensile Requirements by Class – ASTM A453 Grade 660
Hardness Requirements
Stress Rupture Properties (650°C / 1200°F)
A critical requirement for high-temperature fasteners is stress rupture resistance. Per ASTM A453, Class A, B, and C materials must meet the following:
Research confirms that A286 maintains anti-tensile strength not less than 885 MPa at 500°C with stress retention greater than 88.35%, making it the optimal choice for high-temperature fastener applications.
Temperature-Dependent Yield Strength
The following table shows typical yield strength (0.2% offset) at elevated temperatures for A286 in the fully heat-treated condition.
At 500°C, A286 maintains excellent stress retention, with studies showing stress retention rates exceeding 88.35% at this temperature.
Thermal Expansion Advantage of A286 Lock Nuts
A286 is specifically designed for bolting austenitic stainless steel flanges and components operating at elevated temperatures. Its thermal expansion coefficient closely matches that of 304/316 stainless steels, preventing loss of preload during thermal cycling – a critical feature for lock nuts used in high-temperature assemblies where maintaining clamping force is essential.
This expansion match is critical for maintaining preload in high-temperature applications such as turbine casings, exhaust systems, and heat treatment fixtures. Standard alloy steel lock nuts expand less than the surrounding components, leading to loosening and potential failure. A286 eliminates this mismatch.
API 6A & NACE MR0175 Compliance
A286 lock nuts are widely used in oil and gas applications requiring sour service resistance. Per API 6A and API 20F, A286 Grade 660 Class D is approved for H₂S service with maximum hardness of 35 HRC.
Heat Treatment & Microstructural Stability
Optimal mechanical properties in A286 lock nuts are achieved through a two-step heat treatment:
- Solution Annealing: 980°C (1800°F) for 1 hour, oil quench or water quench. This dissolves carbides and prepares the matrix for precipitation hardening.
- Aging (Precipitation Hardening): 718°C (1325°F) for 16 hours, air cool. This forms coherent γ' (gamma-prime) precipitates [Ni₃(Al,Ti)] that provide high-temperature strength.
Metallurgical studies show that aging at 730°C accelerates precipitation kinetics but can lead to overaging and formation of η (eta) phase (Ni₃Ti), which degrades mechanical properties. Our controlled aging at 718°C ensures optimal γ' formation while avoiding η phase precipitation, maximizing creep resistance and long-term stability up to 700°C.
Physical Properties of A286
Corrosion Resistance of A286 Lock Nuts
While A286 is primarily selected for high-temperature strength, it also offers good corrosion resistance in many environments due to its high chromium (14-16%) and nickel (24-27%) content. The alloy exhibits excellent oxidation resistance up to 700°C continuous service and 815°C intermittent service.
Oxidation and Scaling Resistance
The chromium content provides excellent resistance to oxidation and scaling. A286 lock nuts form a protective Cr₂O₃ scale that prevents further oxidation at elevated temperatures. They provide excellent oxidation resistance up to 1500°F (815°C) in conditions typically found in high-temperature exhaust streams.
Corrosion in Other Environments
Critical Corrosion Considerations for Lock Nuts
- Oxidation Resistance: Excellent oxidation resistance up to 1500°F (815°C) in exhaust stream conditions. All-metal lock nuts suitable for continuous service up to 700°C.
- NACE MR0175 Compliance: A286 is qualified for sour service (sulfide stress cracking resistance) in oilfield equipment per NACE MR0175/ISO 15156. Class D with maximum hardness 35 HRC is preferred for sour applications.
- Temperature Limitations: All-metal lock nuts can be used up to 700°C (1300°F). Nylon insert lock nuts are limited to 176°C (350°F).
- Galvanic Corrosion: When paired with lower-grade materials, galvanic corrosion should be considered. A286 is cathodic to most stainless steels but compatible with nickel-based alloys.
- Non-Magnetic Property: A286 is essentially non-magnetic, making it suitable for applications requiring non-magnetic fasteners such as MRI equipment and sensitive instrumentation.
- Flexloc Advantage: All-metal flexloc nuts distribute load evenly due to the fact that they are manufactured as one solid piece, making them the most reliable all-metal self-locking nut for high temperature or corrosive applications.
High-Temperature Engineering Note: For critical applications in aggressive environments, RAYCHIN LIMITED can provide passivation, specialized coatings (Xylan, PTFE, silver plating per AMS 2410), or recommend optimal heat treatment conditions. Third-party corrosion testing per ASTM G31, G48, or G61 available upon request. NACE MR0175 compliant A286 lock nuts available in Class D condition with certified hardness ≤ 35 HRC. A286 offers a cost-effective balance of high-temperature strength and corrosion resistance – approximately 60-70% the cost of nickel-based alloys like Inconel 718.
Special focus: A286 Lock Nuts for Aerospace, Power Generation & Oil & Gas
For critical applications requiring vibration resistance and high-temperature strength, RAYCHIN offers A286 lock nuts manufactured to NAS, MS, AN, DIN, ISO, and customer-specific specifications. Our capabilities include:
- Aerospace Applications: Gas turbine engines, jet engine nacelles, exhaust systems, thrust reverser mechanisms, control systems, airframe structures. Meets NASM 21042, NASM 21209, MS 21042, MS 21045, MS 21046, AN 316 specifications.
- Gas Turbines & Power Generation: Turbine casing bolting, combustion chamber supports, heat exchanger connections, steam turbine components, HRSG systems, generator assemblies.
- Oil & Gas: Offshore platform equipment, subsea assemblies, wellhead components, refinery valve bonnets, sour service per NACE MR0175, high-temperature piping supports.
- Chemical Processing: High-temperature reactors, reformers, crackers, heat exchanger connections, furnace components, thermowell assemblies.
- Automotive: Turbocharger components, exhaust manifold fasteners, high-performance racing applications.
- Heat Treating: Fixture assemblies, tray connections, furnace hardware requiring oxidation resistance up to 700°C.
- Lock Nut Types: All-metal flexloc lock nuts, nylon insert lock nuts, stover lock nuts, elliptical lock nuts, serrated flange lock nuts, 12-point lock nuts.
- Thread Specifications: UNC/UNF, metric coarse/fine, UNJ, MJ – all classes 2B/6H.
- Surface Treatments: Passivation, silver plating (AMS 2410 for anti-galling), PTFE coating, Xylan, cadmium plating (AMS 2400).
- Class Selection: Class A (standard strength), Class B, Class D (higher yield strength, API sour service), Cold Worked (maximum strength).
- Custom: Non-standard thread sizes, special locking features, unique configurations per customer drawings.
All A286 lock nuts are supplied with full traceability and third-party NDT upon request. Sizes available from M2 to M100 (#0 to 4") in all standard configurations. Material certifications (EN 10204 3.1/3.2) included.
Why RAYCHIN LIMITED – The A286 Lock Nut Authority
Metallurgical competence
Engineers on staff with deep expertise in precipitation hardening superalloys. We ensure proper solution annealing (982°C minimum) and precipitation hardening (718°C for 16 hours) for optimal high-temperature strength and creep resistance across all A286 lock nuts. Every heat is verified by in-house testing and PMI verification. With 24-27% nickel and titanium-aluminum precipitation hardening, our lock nuts provide exceptional strength up to 700°C while maintaining excellent corrosion resistance.
Global approvals & traceability
Our quality system is ISO 9001:2015 and AS9100D certified; we also comply with NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN and KS. Full material traceability from melt to final packaging (EN 10204 3.1/3.2). Third-party inspections (ABS, DNV, Lloyds) available. All A286 lock nuts meet applicable AMS, ASTM A453, and NACE MR0175 requirements.
Precision forming & locking element expertise
In-house capability to produce all-metal flexloc lock nuts with segmented collar design, deformed thread lock nuts (stover, elliptical), and precision installation of polymer insert locking elements. Flexloc nuts are manufactured as one solid piece for even load distribution and are certified to 15 cycles of prevailing torque – meeting military standard requirements. Torque testing per IFI 100/107 and NASM 25027 available with full documentation.
Custom solutions
Need a special thread size, unusual locking feature, or custom configuration for your high-temperature application? Our CNC turning and tapping departments handle short runs with agility. We also provide specialized coatings and corrosion testing per customer requirements. Available in Class A, Class B, Class D (API sour service), and cold worked conditions.
Contact the A286 lock nut experts today
Request a quote for A286 all-metal lock nuts, nylon insert lock nuts, prevailing torque nuts, aerospace lock nuts & custom configurations – any global standard (NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN, KS), any quantity. Inquire about high-temperature applications up to 700°C, NACE MR0175 sour service requirements, or flexloc/stover styles.
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