A286 / Alloy 660 for excellent high temperature oxidation resistance

• Good material for high temperature oxidation resistance
• Maintains high strength at elevated temperatures
• Specifications & heat treatment options
• Lock nut specifications
• ASTM A453 Grade 660
• A286 chemistry
• Datasheet for A286
• A286 lock nut availability

A286 nuts, also known as Alloy 660 nuts are stainless steel alloy which contains iron, nickel and chromium. A286 lock nuts are known for their high strength, creep resistance and oxidation resistance at elevated temperatures once age hardened.  As a result, A286 nuts provide high levels of strength from room temperature up to about 1300°F (700°C).

A286 lock nuts are also mildly corrosion resistant. While they should not be used for strong acid environments, they provide excellent oxidation resistance up to 1500°F (815°C) in conditions that would typically be found in high temperature exhaust streams.

Applications

Because of the properties of Alloy 660 / A286, these lock nuts are often found in high temperature engine, manifold, exhaust and turbine applications as well as off-shore oil & gas applications. In addition, A286 / Alloy 660 is also non-magnetic and finds a niche in non-magnetic cryogenic equipment. In addition, we offer bolts and fasteners per ASTM A453 Grade 660. This specification ensures tensile and rupture properties for the most critical high temperature applications.

Resources: A286 Torque Specs

A286 / Alloy 660 Locknut Features and Beneifts

An A286 locknut resists loosening from vibrations and torque. One of the most common styles is a prevailing torque locknut. This kind of A286 / Alloy 660 locknut has a prevailing torque feature which deforms elastically, preventing it from freely spinning like a standard nut.

The two most common and reliable forms of prevailing torque locknuts are the flexloc style and the polymer insert lock nut. An Alloy 660 / A286 flexloc nut is all-metal in composition with a segmented collar that creates six “locking fingers,” that act as a spring. A286 polymer insert lock nuts are often referred to as nylon insert locknuts, although various high performance polymers can be used for the screw threads to “bite into.” Both flexlock and polymer insert locknuts are available in both hexagonal and 12 point configurations.

All Metal Flexloc Lock Nut	Polymer/Nylon Insert Lock Nut
Can be used at high temperatures Distributes load evenly due to the fact that it is manufactured as one solid piece. Is THE most reliable all-metal self-locking nut. As it is all metal, it is best for high temperature or corrosive applications One of the only all-metal lock nuts that is certified to 15 cycles of prevailing torque – which is military standard.	Overall the most reliable locknut, with the only limitation of application temperature Best for low temp applications, typically less than 350°F Various polymers inserts available (Nylon, Vespel, PVDF, etc.) for higher temp. or corrosive applications. Excellent reusability – can reliably be re-used 15 times Eliminates galling and cold-welding common with exotic alloys

Other all metal lock nuts available include the A286 / Alloy 660 stover and elliptical styles. Though these styles are often a cheaper initial cost, they are less reliable than the flexloc style. As these styles delivering less prevailing torque cycles and often result in more failures, the flexloc style is a better investment for both reliability and cost savings.

Lock Nut Specifications

A286 Lock Nut Availability

A286 lock nuts are available in these sizes. Please contact us for price and lead times.

Lock Nut Sizes
•  #00 - 10"
•  M1.2 - M250

ASTM A453 Grade 660

Material specification ASTM A453 Grade 660 applies to bolts, studs, studs and other fasteners. It ensures fasteners meet strength standards for use in high temperature bolting applications. ASTM A453 Grade 660 is classified into 4 property classes / heat treatments: A, B, C & D, each designated with different tensile and stress rupture properties. The most common of the ASTM 453 classes are class A or D. The grades A, B and C all have the same minimum tensile strength and minimum yield strength of 130ksi and 85ksi respectively. However grade D has a significantly better yield with a min tensile of 130ksi and a min yield of 105ksi.

Additional A286 / Alloy 660 Specifications, Cold Working & Heat Treatments

AMS A286 / Alloy 660 Heat Treatments

By AMS numbers, the most common for A286 / Alloy 660 is AMS 5737 (same as Grade A) and then AMS 5732 (same as Grade B).

A286 / Alloy 660 Cold Worked Fasteners

For additional strength, A286 could be aged and cold worked to achieve a min ultimate tensile strength of 160ksi upon request.

Additional Specifications

UNS S66286, ASTM A453, AMS 5525, AMS 5726, AMS 5732, AMS 5737, AMS 5804, EN 1.4980, GE B50T1181, GE B50T12, GE B50T81, Werkstoff 1.4980, ASTM F2281

A286 / Alloy 660 Chemistry

Mechanical Properties