Countersunk hex screw | A4 | DIN 7991
Do you need a countersunk socket screw that performs reliably even in humid, salty, or chemically demanding environments? Countersunk socket screw ISO 10642 in A4 / AISI 316 acid-proof stainless steel is built to withstand corrosion and maintain strength over a long period. It combines a low-profile countersunk head with high breaking strength and is optimized to withstand heavy mechanical loads and frequent use.
AREA OF APPLICATION
Perfect for mounting equipment, machinery, and structures where a smooth and flush surface is important – for example, in coastal areas, docks, boat equipment, the food industry, or chemical plants. The countersunk head ensures the screw does not protrude above the material surface, providing a neat and secure fastening. Easy to install with an Allen key and requires minimal maintenance even during continuous operation.
Watch video: Tightening torque for stainless steel screws
TECHNICAL SPECIFICATIONS
Product type: Countersunk socket screw
Standard: DIN 7991 (corresponds to ISO 10642)
Grade: A4 / AISI 316 acid-proof stainless steel
Material class: A4-70
Thread type: Metric ISO thread
Surface treatment: Untreated (natural stainless steel)
Head shape: Countersunk (flat head, conical head)
Drive type: Hex socket (Allen key)
FREQUENTLY ASKED QUESTIONS (FAQ)
What does it mean that the screw is countersunk according to ISO 10642 (formerly DIN 7991)?
ISO 10642 specifies the standard for countersunk socket screws. The conical head is tapered to fit completely into the material so that the screw head lies perfectly flush with the surrounding surface. This provides a smooth, aerodynamic, and safe finish without protruding edges where objects can snag or cause injury.
Why is acid-proof A4 / AISI 316 the right steel choice for humid and chemically demanding environments?
Acid-proof A4 steel (AISI 316 / 1.4401) contains molybdenum, which provides superior protection against pitting and stress corrosion caused by saltwater, chlorine, acids, and aggressive chemicals. This makes the screw ideal for marine installations, coastal construction, the food industry, and chemical process plants.
What should one keep in mind regarding tool grip and tightening torque for ISO 10642?
Because the countersunk head has a smaller socket than, for example, a socket head cap screw (ISO 4762/DIN 912), you should use a high-quality, well-fitting hex key or bit. It is important to tighten with the correct torque to avoid damaging the socket, especially when installing in hard materials.