The surface treatment of lifting chains is very important as it relates to the chain's anti-corrosion performance, appearance, and service life. The choice of treatment method depends on the working environment of the chain, load requirements, budget, and whether a specific appearance is required. Blackening Treatment: Purpose: Mainly for rust prevention and aesthetics, providing some anti-corrosion capability. Principle: A dense layer of iron oxide film (Fe3O4) is formed on the surface of steel through chemical or heat treatment (such as alkaline blackening, room temperature blackening). The surface appears black or bluish-black. Advantages: Lower cost; low treatment temperature, which does not affect the mechanical properties of the chain base material; uniform and aesthetically pleasing appearance (black); can provide some short-term anti-rust ability. Disadvantages: Very weak anti-corrosion capability.