- Definition and Standard of G80 Chain
G80 is the strength grade mark of lifting chain, which complies with the international standard ISO 3077 or the Chinese national standard GB/T 20946. Its minimum breaking strength is 800MPa and the safety factor is 4 times. It belongs to high-strength alloy steel chain. The chain material is usually made of high-quality alloy steel such as 20Mn2 or Q235, and the hardness and toughness are improved through heat treatment processes such as quenching and tempering.
Hot-dip galvanizing is to immerse the chain in molten zinc liquid (about 435-450℃) to form a zinc-iron alloy layer. The coating thickness can reach 30-60 microns, which has both mechanical protection and electrochemical anti-corrosion functions. Compared with cold galvanizing, it has stronger adhesion and a service life of more than 20 years, which is particularly suitable for harsh outdoor environments.
- Manufacturing process and quality control
The production of G80 hot-dip galvanized chain covers three core links: material processing, welding, and hot-dip galvanizing:
①. Material processing and forming
After quenching, tempering and other heat treatments, the alloy steel is welded into chain links by a fully automatic welding machine. Quenching increases the hardness and tensile strength of the steel, while tempering reduces brittleness, ensuring that the chain is not easy to break under high load.
②. Hot-dip galvanizing process
Including degreasing, pickling, plating, drying, zinc dipping, cooling and passivation steps:
– Pretreatment: pickling to remove surface oxides, and plating agents (such as NH₄Cl and ZnCl₂ mixed solution) to prevent secondary oxidation and enhance the adhesion of the zinc layer.
– Zinc dipping: Control the zinc liquid temperature (435-445℃) and the dipping time (0.5-1.5 minutes) to form a dense zinc-iron alloy layer.
– Post-treatment: water cooling to fix the coating, passivation treatment (such as chromate) to prevent white rust.
③. Quality inspection
It is necessary to pass the appearance inspection (no cracks, deformation), thickness measurement (magnetic thickness gauge) and adhesion test (bending or scratch test) to ensure compliance with the G80 standard.
III. Performance advantages and application areas
Performance characteristics:
– High strength: G80-grade chain can withstand 4 times the safe load and is suitable for heavy-load scenarios.
– Corrosion resistance: The hot-dip galvanized layer isolates oxygen and moisture, and the sacrificial anode effect of zinc further delays the corrosion of the matrix.
– Long life: In marine or humid environments, the service life is 3-5 times longer than that of ordinary chains.
Typical application scenarios:
①. Ships and ports: used for hatch cover fixing, anchor chains and cargo lifting, adapted to high salt spray environments.
②. Lifting equipment: such as hand hoists and electric hoists, commonly seen on construction sites and mine hoists.
③. Protective facilities: fixed chains for highway guardrails and bridge cables, with both strength and durability.
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- Maintenance and care points
- Regular inspection: Observe whether the chain is deformed or rusted, whether the rollers and pins are worn, and replace damaged links in time.
- Lubrication management: Use lithium-based grease to reduce friction and avoid dry grinding that causes plating to peel off.
- Adjust the tightness: The chain sag should be controlled at 2%-3% of the center distance. Too tight increases wear, and too loose is easy to decouple.
- Avoid mixing: New and old chains cannot be mixed to avoid uneven force causing breakage.
- Summary
G80 hot-dip galvanized chain achieves a balance between high strength and long-term corrosion protection through the combination of material optimization and advanced galvanizing process. Its wide application in heavy industry, marine engineering and other fields confirms its reliability as a key safety component. In the future, with the innovation of galvanizing technology (such as chromium-free passivation process) and the popularization of intelligent production equipment, the performance and environmental protection of G80 chain will be further improved. When purchasing, users need to pay attention to the manufacturer’s qualifications (such as CE certification) and customized services to ensure the adaptability of the chain to specific working conditions.
