Hexagon socket head cap screws to ISO 4762 (DIN 912), M1,6 to M64 coarse pitch, product grade A. The screws photographed are stainless with an A2-70 head marking. Driven by hexagon key where a spanner cannot reach.
Prices on request. Contact us for availability and quotations.
A hexagon socket head cap screw has a cylindrical head with a hexagon socket sunk into it, so it is driven with a hexagon key from directly above rather than with a spanner across flats. That allows it to be used in counterbored holes, in recesses and in tight machine assemblies where there is no room to swing a spanner, and it seats flush or below the surface when counterbored.
ISO 4762, which supersedes DIN 912, specifies these screws with coarse pitch thread from M1,6 up to and including M64 in product grade A - the closer of the two dimensional tolerance grades. The socket size is fixed by the screw diameter, so a set of hexagon keys covers the range.
The screws in the product photograph carry an A2-70 head marking: austenitic stainless steel of the 304 family, cold worked to a property class of 700 MPa minimum tensile and 450 MPa minimum yield under ISO 3506-1. Where higher strength is required these screws are also made in carbon steel class 12.9 (1220 MPa tensile, 1100 MPa yield), but ISO 898-1 prints a caution against 12.9 in environments that can cause stress corrosion cracking, and 12.9 must not be electroplated without a hydrogen bake-out. For coastal exposure the stainless grade to ask for is A4, the 316 family with 2 to 3 % molybdenum.
When ordering, state thread size and length, the property class or stainless grade, and whether a plain, spring or serrated washer is wanted beneath the head. Check the counterbore depth against the head height for the size chosen.
| Standard | ISO 4762:2004 (supersedes DIN 912) - hexagon socket head cap screws |
|---|---|
| Thread Size Range | M1,6 to M64 inclusive, coarse pitch thread, product grade A |
| Material (items photographed) | Austenitic stainless steel, head marked A2-70 |
| Property Class A2-70 | 700 MPa minimum tensile, 450 MPa minimum yield (ISO 3506-1 class 70, 304 family) |
| Corrosion Grade Options | A2 (304 family, no molybdenum requirement) or A4 (316 family, 2,00 - 3,00 % Mo, the grade for chloride exposure) |
| Carbon Steel Option | Class 12.9 - 1220 MPa minimum tensile, 1100 MPa minimum yield, 385 - 435 HV; alloy steel, quenched and tempered |
| Class 12.9 Caution | ISO 898-1 Table 2 note (i) warns of stress corrosion cracking of class 12.9 fasteners, coated or uncoated; do not electroplate 10.9 or 12.9 without a hydrogen bake-out |
