Shelling and descaling of high-strength bolts

The process of removing iron oxide plate from cold heading steel wire rod is stripping and descaling. There are two methods: mechanical descaling and chemical pickling. Replacing the chemical pickling process of wire rod with mechanical descaling improves productivity and reduces environmental pollution. This descaling process includes bending method, spraying method, etc. The descaling effect is good, but the residual iron scale cannot be removed. Especially when the scale of the iron oxide scale is very strong, so the mechanical descaling is affected by the thickness of the iron scale, the structure and the stress state, and is used in carbon steel wire rods for low-strength fasteners. After mechanical descaling, the wire rod for high-strength fasteners undergoes a chemical pickling process to remove all the iron oxide scales, that is, compound descaling. For low carbon steel wire rods, the iron sheet left by mechanical descaling is likely to cause uneven wear of grain drafting. When the grain draft hole adheres to the iron sheet due to the friction of the wire rod and the external temperature, the surface of the wire rod produces longitudinal grain marks.