Interpret the amount of zinc in hot dip galvanizing
1. Definition and importance of zinc content of hot dip galvanizing
• Definition: Zinc content refers to the thickness or weight of the zinc layer formed on the surface of steel products through the hot-dip galvanizing process, which is an important indicator to measure the protective performance of the hot-dip galvanizing layer.
• Importance: The amount of zinc in hot dip galvanizing directly affects the corrosion resistance and service life of steel products. Sufficient zinc content can form an effective protective layer to prevent the chemical reaction between the steel matrix and the water and oxygen in the external environment, thereby delaying the corrosion process.
2. Calculation method of zinc content of hot-dip galvanizing
• Theoretical calculation: The amount of zinc in hot dip galvanizing can theoretically be obtained by calculating the difference in the weight of the steel before and after galvanizing, and then dividing by the surface area of the steel. In addition, it can also be calculated by zinc coating thickness and zinc density, the formula is: zinc content (g/m²)= zinc coating thickness (μm)× zinc density (g/cm³)÷ 10000.
• Actual measurement: In actual production, the amount of zinc in hot dip galvanizing is usually measured by instruments such as coating thickness gauges. This method can reflect the thickness and distribution of zinc layer more accurately.
3. Factors affecting the amount of zinc in hot dip galvanizing
• Steel matrix: the composition and surface state of the steel affect the adhesion and uniformity of the zinc layer, which affects the zinc content. For example, steel with a high carbon content is prone to hydrogen embrittlement during hot dip galvanizing, which affects the adhesion of the zinc layer.
• Galvanizing process: the temperature, composition, dipping time, lifting speed and other process parameters of the galvanizing solution will affect the thickness and uniformity of the zinc layer. For example, increasing the temperature of the galvanizing solution can speed up the formation of the zinc layer, but too high a temperature may cause the zinc layer to be too thick or uneven.
• Follow-up treatment: The cooling rate and passivation treatment after hot dip galvanizing will also affect the performance and zinc content of the zinc layer. Proper cooling rate can maintain the integrity and adhesion of the zinc layer; Passivation treatment can form a protective film on the surface of the zinc layer to improve the corrosion resistance.
4. Application and standard of zinc content of hot dip galvanizing
• Application: Zinc content is widely used in the anti-corrosion protection of steel products, such as steel structure, pipelines, wires and cables. Different fields and application scenarios have different requirements for zinc content.
• Standards: In order to regulate the quality and performance of hot-dip galvanized products, countries have developed corresponding standards and specifications. These standards usually specify the zinc layer thickness, adhesion strength, corrosion resistance and other indicators of hot-dip galvanized products. For example, China's national standard GB/T 13912-2002 has made clear provisions on the zinc layer thickness and adhesion strength of hot dip galvanized double-layer products.
How much galvanizing amount is corresponding to hanging galvanizing and blowing galvanizing respectively?
1. Galvanized amount of hanging galvanized
• Galvanizing range: The galvanizing amount of hanging galvanizing is relatively high, the zinc layer thickness can generally reach 60-85 microns or more, and the corresponding galvanizing amount is also large. Specific values may vary according to product specifications, applications and customer requirements.
• Influencing factors: The amount of galvanized hanging is affected by a variety of factors, such as the temperature of the galvanized solution, composition, dipping time, lifting speed and the surface state of the steel. These factors together determine the thickness and uniformity of the zinc layer, which affects the amount of galvanizing.
2. Galvanizing amount of blowing galvanizing
• Galvanizing range: The galvanizing amount of blow galvanizing is relatively low, the zinc layer thickness is generally about 20 microns, and the corresponding galvanizing amount is also small. This is mainly due to the characteristics of the blow galvanizing process, which is suitable for some small steel products, such as Angle steel, small-caliber pipes and so on.
• Influencing factors: Similar to hanging galvanizing, the amount of galvanizing blown galvanizing is also affected by a variety of factors, such as the temperature of the galvanizing liquid, the composition, the blowing pressure, the blowing time, and the surface state of the steel. The change of these factors will affect the formation and adhesion effect of zinc layer, thus affecting the amount of galvanizing.
3. Comparison and influencing factors of galvanizing amount between hanging and blowing galvanizing
• Comparison of galvanizing amount: The galvanizing amount of hanging galvanizing is significantly higher than that of blowing galvanizing. This is because the hanging galvanizing process is suitable for large steel products, which requires a thicker zinc layer to provide adequate anti-corrosion protection; The blow galvanizing process is more suitable for small products, and the zinc layer thickness is relatively thin.
• Comparison of influencing factors: The amount of zinc plating by hanging galvanizing and blowing galvanizing is affected by a variety of factors, but the degree and way of influence are different. For example, the temperature and composition of the galvanizing solution have an important impact on both processes, but hang galvanizing may be more concerned with the uniformity and adhesion of the zinc layer, while blow galvanizing is more concerned with the formation rate and efficiency of the zinc layer. In addition, the surface state of the steel is also one of the key factors affecting the amount of zinc plating in the two processes.
