Structure: Standard welded round chain. Each link is bent from round steel into a ring shape, and then the two ends are butt-welded together using resistance flash welding to form a strong weld joint. These chains are usually short links (with a pitch shorter than 5 times the diameter of the chain), which have good flexibility and resistance to twisting. Material: High-quality alloy structural steel (such as 20Mn2, 23MnNiMoCr54, etc.) is used. Through strict chemical composition control and accurate heat treatment processes (quenching + tempering), the required strength, hardness, and toughness of G80 grade are achieved. Surface treatment: There are usually several types: Blackening (boiling black): A common treatment method that forms a dense layer of black oxide film, providing basic rust resistance at a low cost. Galvanizing: Provides better rust and corrosion resistance, suitable for humid or corrosive environments (such as ports, oceans, chemical plants). There are hot-dip galvanizing and electroplating zinc options. Coating with oil: Factory-applied anti-rust oil provides temporary protection.