Stainless steel strip pipe and stainless steel threaded pipe

It may be due to a strong reaction between iron and zinc. The strong reaction caused the integrated coating composed of the original aluminum alloy layer and pure zinc layer to become a state where only the aluminum alloy layer has no pure zinc layer. Dark gray or dark gray is the color of iron and zinc aluminum alloys. In addition, if the quality of the zinc solution deteriorates, the iron content in the zinc solution will also increase. After hot dip galvanizing, the pure zinc layer of the product will become gray due to iron elements, leading to color deviation.

Main reasons:

(1) The coating raw materials contain more classic materials such as carbon, silicon, sulfur, and phosphorus. Due to the inert electrodes formed by these elements, the electrochemical corrosion between iron and zinc is also high, resulting in an aggravation of the iron zinc reaction.

⑵ The low content of chemical elements such as aluminum in zinc solution cannot effectively prevent the iron zinc reaction of galvanized materials such as active steel.

(3) The increase in iron content in zinc solution leads to a deterioration in the quality of the zinc solution.

Rectification measures:

(1) Choose a suitable temperature for the hot dip galvanizing environment based on the combination of materials;
⑵ Adjust the composition of the zinc solution to control the aluminum and nickel content within the corresponding range;
(3) Minimize the soaking time as much as possible;
(4) After starting the pot, cool it as soon as possible.
(5) Immediately purify and treat the zinc solution to ensure its quality.