Dacromet Hex Bolts: Superior Corrosion Resistance and Long-Lasting Performance 

3. The Dacromet Coating Process for Hex Bolts

The production of Dacromet hex bolts follows a carefully controlled non-electrolytic process that ensures uniform coverage and eliminates hydrogen embrittlement risks:

1.Surface preparation: Hex boltsare thoroughly cleaned to remove oil, grease, scale, and contaminants to ensure optimal adhesion of the Dacromet

2.Coating application: Cleaned boltsare immersed in a water-based slurry of zinc and aluminum flakes with binders. Dip-spin or spray methods ensure even coating on all surfaces of the hexagonal bolts, including threads and recesses.

3.Curing: After excess slurry is removed, the coated boltsare baked at approximately 300°C. The inorganic binder solidifies and bonds the zinc-aluminum flakes to the steel, forming the protective Dacromet

4.Inspection: Finished Dacromet boltsare checked for coating thickness, appearance, adhesion, and corrosion resistance. Optional topcoats may enhance lubricity or color.

Because the Dacromet process involves no acid pickling or electrolytic deposition, there is no risk of hydrogen embrittlement. This makes Dacromet particularly suitable for high-strength hex bolts of grades 8.8, 10.9, and 12.9.

4. Key Advantages of Dacromet Hex Bolts

Dacromet hex bolts deliver a unique combination of performance benefits that set them apart from ordinary galvanized or plated bolts:

4.1 Outstanding Corrosion Resistance

The most important feature of Dacromet (Darcomet) is its exceptional anti-corrosion capability. Standard Dacromet-coated bolts typically achieve over 1,000 hours of salt spray resistance without red rust; high-performance grades can exceed 2,000 hours. Compared with traditional electro-galvanizing, Dacromet bolts offer 7 to 10 times better corrosion protection. Even in cyclic corrosion tests and sulfur dioxide environments, Dacromet hex bolts maintain excellent integrity.

4.2 No Hydrogen Embrittlement

High-strength bolts are vulnerable to hydrogen embrittlement when processed by conventional electroplating. The Dacromet process completely avoids this risk because it is non-electrolytic. As a result, Dacromet hex bolts of high tensile grades remain safe and reliable under load, making them ideal for critical structural and automotive applications.

4.3 Excellent Heat Resistance

Dacromet coatings remain stable at temperatures up to 300°C or higher. Traditional zinc coatings begin to crack or lose corrosion resistance above 70–100°C and may fail at 200–300°C. In contrast, Dacromet-coated bolts retain both appearance and protective performance under prolonged high-temperature exposure—valuable in engine compartments, exhaust systems, and industrial equipment.

4.4 Superior Penetration and Thin Film

The dip-spin application of Dacromet ensures the coating penetrates deep recesses, threads, and blind holes of hex bolts. With a typical thickness of only 6–10 μm, the Dacromet film does not significantly alter thread dimensions, allowing Dacromet hex bolts to be used with standard nuts. This high permeability provides complete anti-corrosion protection even on complex geometries.

4.5 Good Adhesion and Recoatability

Dacromet coatings adhere strongly to the steel substrate and accept additional organic topcoats or paints very well. This flexibility supports customized friction coefficients and color coding for different series of bolts.

5. Applications of Dacromet Hex Bolts

Thanks to their superior corrosion resistance and reliability, Dacromet hex bolts are widely specified across multiple industries:

Automotive and transportation: Chassis, suspension, body, and engine boltsrequiring long-term anti-corrosion performance under road salt and weather exposure.

Construction and infrastructure: Structural boltsfor bridges, towers, transmission lines, and coastal buildings where Dacromet protection significantly extends service life.

Marine and offshore: Hex boltsused on ships, offshore platforms, and port equipment benefit from the outstanding salt-spray resistance of Dacromet.

Renewable energy: Wind turbine towers and solar mounting systems employ Dacromet-coated boltsfor reliable outdoor corrosion protection.

Industrial machinery: High-strength boltsin chemical plants, power generation, and heavy machinery rely on Dacromet for durability in corrosive conditions.