Blackening treatment and connection method of

steel structure bolts

         Steel structural bolts belong to the category of fasteners in hardware. Most of the colors we see are black. Ordinary bolts are generally made of ordinary carbon structural steel without heat treatment. High strength bolts are generally made of high-quality carbon structural steel or alloy structural steel, which need quenching and tempering heat treatment to improve the comprehensive mechanical properties. The main treatment methods for blackening of steel structure bolts are as follows:   

     1. BRN treatment. In the special equipment, special ion modification method is used. It has the advantages of good adhesion, beautiful surface color, good wear resistance, compact surface, controllable film thickness, no discoloration and falling off. 

       2. Chemical heat treatment. 

        The steel structure bolts are treated in special equipment, the film is firm, the adhesion is good, the color is beautiful, the wear resistance is good, the surface is dense.       3. Electrolytic oxidation method.

        The film is thick and black with poor light resistance and easy to crack automatically. 

        4. Chemical Blackening method.

        This method can be divided into acid blackening and alkaline blackening. The acid blackened film has uniform color, thin and firm, elastic and good adhesion. However, the film is porous and has poor wear resistance, which needs curing treatment to improve the wear resistance. Alkaline blackening time is relatively long, but the wear resistance of the black film is very good, no curing treatment is needed. 

 The above is the treatment method of steel structure bolt blackening, which we can often use. In addition, there are two connection methods of steel structure bolt, one is cold processing connection method of high strength bolt, and the other is hot processing connection method of high strength bolt.We can choose according to different requirements when using in production and processing. Cold working connection is rigid connection, while hot processing connection is flexible connection. 

        The company's main business: steel structure nuts, steel structure bolts, high strength nuts, high strength bolts, special-shaped nuts, special-shaped bolts