DIN 792 Cylindrical Countersunk Screw / Cylindrical Nib Bolts

About DIN 792 Cylindrical Countersunk Screw / Cylindrical Nib Bolts

Cylindrical nib bolts are specialized heavy-duty industrial fasteners featuring a smooth cylindrical head with a protruding locking nib or key underneath. This unique geometry locks the bolt into a matching slot or recessed groove in the application surface, preventing the bolt from rotating during installation or high-vibration operations. They are widely utilized in heavy machinery, mining equipment, automotive assemblies, and structural steel connections where single-sided tightening is necessary.

Material grades

High-temperature stainless steel

• Grade 310/310S: Contains high chromium and nickel content. Excellent oxidation resistance up to 1035C.

• Grade 321/347: Stabilized with titanium or niobium. Prevents carbide precipitation during high-temperature welding applications.

High tensile carbon and alloy steel

• Grade 8.8: Medium carbon steel, quenched and tempered. Offers standard structural strength up to 800 MPa.

• Grade 10.9: Alloy steel, quenched and tempered. Provides high structural strength up to 1040 MPa.

• Grade 12.9: High-performance alloy steel. Offers maximum tensile strength up to 1220 MPa for heavy machinery.

Hastelloy

• Grade C276: Exceptional resistance to strong reducing and oxidizing acids. Prevents pitting and stress corrosion cracking.
• Grade B3: Specially formulated for superior resistance to hydrochloric acid at all concentrations and temperatures.

Inconel

• Grade 625: High strength and excellent fabricability. Resists severe pitting and crevice corrosion in marine environments.

• Grade 718: Precipitation-hardened nickel-chromium alloy. Combines high yield strength with creep-rupture properties up to 700C.

Monel

• Grade 400: Solid-solution binary alloy of copper and nickel. Highly resistant to rapidly flowing seawater and hydrofluoric acid.

• Grade K500: Combines the corrosion resistance of Grade 400 with added strength and hardness via aluminium and titanium additions.

Surface finishes

• Hot-dip galvanized: Thick zinc layer applied via molten bath immersion. Offers long-term sacrificial outdoor atmospheric corrosion protection.

• Zinc plating: Thin electrochemically deposited zinc layer. Provides mild corrosion resistance with a bright, aesthetically clean finish.

• Polishing: Mechanical smoothing of the base metal. Minimizes surface crevices, enhances aesthetic shine, and improves stainless steel passive film.

• Black phosphating: Chemical conversion coating that absorbs anti-corrosion oils. Provides anti-galling properties, low light reflectivity, and light moisture protection.

Versatile Materials and Application Range

The DIN 792 cylindrical countersunk screws are engineered using materials like carbon steel, alloy steel, stainless steel (A2, A4), brass, or bronze, ensuring durability and adaptability. Their corrosion-resistant properties, selection of finishes, and compatibility with both indoor and outdoor-including high humidity and marine-environments make them ideal for machinery, automotive, structural, and heavy-duty applications.


Precision and Customization for Every Project

Customers have the flexibility to specify bolt length, diameter, threading, and head marking, including options for surface treatments such as zinc, nickel, or hot-dip galvanizing. Products comply with industry regulations (RoHS, ISO, REACH) and can be supplied with certificates upon request. Fasteners are available in standard and bespoke dimensions to meet unique requirements.


Reliable Stock and Certified Supply

DIN 792 fasteners are available in ready stock for common sizes, with custom specifications fulfilled within 2-4 weeks. Bulk and specialized packaging options cater to various project needs. Certificates (Test, Material Traceability, Mill) are provided on request, ensuring transparency and product integrity. All fasteners are manufactured to DIN 792 standards, guaranteeing high performance and reliability.