Comprehensive analysis of galvanized angle steel: hot-dip galvanizing vs cold-dip galvanizing, how to choose?

1. Process principle and characteristics
Hot-dip galvanizing process
Hot-dip galvanizing is to immerse the angle steel in molten zinc liquid (temperature is about 450-480℃), so that the zinc reacts with the steel surface to form a zinc-iron alloy layer with a thickness of 50-100μm. The coating of this process is metallurgically combined with the steel, with a dense structure and strong durability, and can resist strong corrosive environments such as acid and alkali mist. The appearance of hot-dip galvanized angle steel is silvery white, and there may be process water marks or nodules on the surface, but these characteristics do not affect its anti-corrosion performance.

Cold galvanizing process
Cold galvanizing (electrogalvanizing) deposits a zinc layer with a thickness of 5-15μm on the surface of the angle steel through electrolysis. This process is carried out at room temperature and does not require high-temperature melting, so the cost is low. The surface of cold-dip galvanized angle steel is smooth and has high gloss, but the zinc layer is thin and has weak adhesion, and local corrosion is prone to occur after long-term use.

2. Performance comparison and applicable scenarios
 Anti-corrosion performance
The zinc layer thickness of hot-dip galvanized angle steel is much higher than that of cold-dip galvanizing, and it forms a metallurgical bond with steel, so its corrosion resistance is significantly better than that of cold-dip galvanizing. Hot-dip galvanized angle steel is suitable for building structures, bridges, pipelines, etc. that are exposed to the natural environment for a long time, and the anti-corrosion life can reach 20-30 years. The zinc layer of cold-dip galvanized angle steel is thinner and has weaker corrosion resistance, which is more suitable for indoor or short-term protection scenarios, such as automotive accessories, electrical appliance housings, etc.

Appearance and decoration
The surface of cold-dip galvanized angle steel is smooth and glossy, and it can present decorative effects such as color and military green through passivation treatment, so it has more advantages in occasions with high appearance requirements. The surface of hot-dip galvanized angle steel may have zinc flowers or process water lines, and the appearance is relatively rough, but the brightness can be improved by polishing or mirror treatment.

Cost and environmental protection
The cost of cold-dip galvanizing process is low, and the solvent and diluent do not contain highly toxic organic solvents, which meets environmental protection requirements. The hot-dip galvanizing process has high energy consumption, but the coating has a long life and is more cost-effective in the long run.

3. Selection suggestions

Choose according to the use environment

Long-term outdoor environment: hot-dip galvanized angle steel is preferred, and its corrosion resistance can meet the long-term protection needs.

Indoor or short-term protection: cold-dip galvanized angle steel has a lower cost and is suitable for occasions where corrosion protection is not required.

Choose according to the project budget

Sufficient budget: The initial cost of hot-dip galvanized angle steel is high, but the long-term maintenance cost is low, which is suitable for projects with strict quality requirements.

Limited budget: cold-dip galvanized angle steel can reduce initial investment, but regular maintenance or replacement is required.

Choose according to appearance requirements

High decorative requirements: cold-dip galvanized angle steel has richer gloss and color options.

High functional requirements: hot-dip galvanized angle steel has stronger durability and resistance to mechanical damage.

4. Precautions
Supplier reputation: Choose galvanized angle steel produced by regular manufacturers to ensure that the zinc layer thickness and quality meet the standards.
Detection method: The zinc layer thickness can be measured by a zinc meter, or the galvanizing process can be preliminarily judged by observing the surface gloss, zinc flowers and other characteristics.
Installation and maintenance: Galvanized angle steel should avoid scratching the coating during transportation and installation, and regularly check and repair local corrosion areas.
5. Summary
Hot-dip galvanized and cold-dip galvanized angle steels have their own advantages and disadvantages. When choosing, you need to consider the use environment, budget, appearance requirements and other factors. Hot-dip galvanized angle steel has become the first choice for outdoor projects with its excellent anti-corrosion performance and durability, while cold-dip galvanized angle steel has a place in indoor or short-term protection scenes with its low cost and decorativeness. Through scientific selection and standardized construction, the performance advantages of galvanized angle steel can be fully utilized and its service life can be extended.