A286 / Alloy 660 for excellent high temperature oxidation resistance
- Good material for high temperature oxidation resistance
- Maintains high strength at elevated temperatures
- A-286 chemistry, specs & heat treatments
A286 screws, also known as Alloy 660 screws are stainless steel alloy which contains iron, nickel and chromium. A286 flat head screws are known for their high strength, creep resistance and oxidation resistance at elevated temperatures once age hardened. As a result, A286 screws provide high levels of strength from room temperature up to about 1300°F (700°C).
A286 flat head screws 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.
Because of the properties of Alloy 660 / A286, these flat head screws 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.
Resources: A286 Torque Specs
A286 / Alloy 660 flat head screws are characterized by having a head with a top flat surface (which can feature either a slotted, phillips or allen driver) and bottom that is cone shaped or countersunk. With this design, the head of the screw can align flush or below the surrounding surface having obvious benefits.
A286 Slotted vs. Phillips Driver
|Slotted Head Advantages||Phillips Head Advantages|
For most flat head screw designs the angle of countersink is usually 82° for UNC and UNF applications however other angles ranging from 60° -120° could be specified.
|Thread Type||Normal Flat Head Countersink Angle|
UNC / UNF
|ISO Metric / Imperial||90°|
A-286 / Alloy 660 Heat Treatments: There are several heat treatment combinations for A-286 (Alloy 660) all with slight variations in performance. They can be specified via an AMS number or Class: A, B, C or D, with most common specified as 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. 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: For additional strength, A286 could be aged and cold worked to achieve a min ultimate tensile strength of 160ksi upon request
A286 Specifications: ASTM A453, AMS 5525, AMS 5732, AMS 5737, AMS 5804, EN 1.4980, GE B50T1181, GE B50T12, GE B50T81, UNS S66286, Werkstoff 1.4980