ISO14579 Hexalobular Socket Head Cap
Screws ISO14579 Hexalobular Socket Head Cap Screws
Applications/Advantages
Ideal for precision assembly work with close tolerances and applications needing a well-tooled appearance. Supplies greater tensile strength than equivalent sizes of Grade-5 or Grade-8 hex head cap screws while requiring less surface area or counterbore since the fastener is internally-wrenched.
Material
Cap screws shall be made from an alloy steel which conforms to the following chemical composition requirements (per product analysis): Carbon: 0.31% minimum; Phosphorus: 0.040% maximum; Sulfur: 0.045% maximum. Also, one or more of the following elements shall be present in sufficient quantity to meet the strength requirements listed below: chromium, nickel, molybdenum, or vanadium.
Heat Treatment
Cap screws shall be heat-treated by oil-quenching from above the transformation temperature and then tempered at a temperature not lower than 650°F.
Hardness
0 through 1/2" diameters: Rockwell C39 minimum; 5/8" diameter and larger: Rockwell C37 minimum
Cap Screws of Length 3D or Greater
Where D equals the nominal diameter of the screw, are subject to tensile strength, yield strength, elongation, and reduction of area testing.
Tensile Strength
0 through 1/2" diameters: 180,000 psi minimum; 5/8" diameter and larger: 170,000 psi minimum
Yield Strength
0 through 1/2" diameters: 162,000 psi minimum; 5/8" diameter and larger: 153,000 psi minimum
Elongation
10% minimum (applies to machined specimens of length at least 4D where D equals the nominal diameter of the screw)
Reduction of Area
33% minimum (applies to machined specimens)
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