Hot-dip galvanized bolts are divided into ordinary hot-dip galvanized bolts and hot-dip galvanized bolts with reamed holes. According to the shape of the head: there are hexagonal head, round head, square head, countersunk head and so on. One of the most commonly used is the hexagonal head. Hot-dip galvanized bolt countersunk heads are generally used where connection is required. It is a non-standard part, and the shape is U-shaped, so it is also called U-bolt. The hot-dip galvanized bolt has threads on both ends and can be combined with a nut. It is mainly used to fix tubular or sheet objects, because the way of fixing objects is like a person riding on Immediately, it is called riding bolt.
For connecting bolts for steel structures, unless otherwise specified, hot-dip galvanized bolts are usually ordinary crude grade C bolts.
① The bolts of grade A and grade B bolts are machined by lathes, with smooth surface and precise size.The material performance grade is 8.8, the production and installation are complicated, the price is high, and it is rarely used;
②Class C bolts are made of unprocessed round steel, the size is not accurate enough, and the material performance level is 4.6 or 4.8. Large deformation during shear connection, but easy installation and low production cost, it is mostly used for tensile connection or temporary fixation during installation. Indispensable, bolts are also called industrial meters. It can be seen that the bolts are widely used. The application range of bolts includes: hot-dip galvanized bolts, electronic products, mechanical products, digital products, electrical equipment, electromechanical products. Bolts are also useful in ships, vehicles, water conservancy projects, and even chemical experiments.
Anyway, bolts are used in many places. Such as precision bolts used on digital products. The magnetic particle inspection of hot-dip galvanized bolts uses the interaction between the leakage magnetic field at the bolt defect and the magnetic powder, aiming at the difference between the magnetic permeability of the bolts (such as cracks, slag inclusions, mixing, etc.) and the magnetic permeability of the steel after magnetization. The magnetic field at the discontinuity of these materials will be turbulent, forming part of the magnetic flux leakage, and the surface of the workpiece will generate a leakage magnetic field, thereby attracting the accumulation of magnetic powder at the defect formation of the magnetic powder—magnetic marks. The hot-dip galvanized bolts are under appropriate lighting conditions. The defect position and shape are revealed, and the accumulation of these magnetic powders is observed and explained, and the purpose of rejecting defective products has been achieved.