Why Does Hot-dip Galvanized Precision Seamless Steel Pipe Cause Chromatic Aberration

Hot-dip galvanized precision seamless steel pipes are gray or dark gray. Sometimes the surface pure zinc layer of pipe turn into gray after galvanizing due to iron content, causing color difference. Why does this happen?


Specific reason:

1. The material of the plated parts contains lots elements such as carbon, silicon, sulfur, and phosphorus. The electrochemical reaction between iron and zinc is due to the inert electrode formed by this type of element, and the relative potential becomes higher, which causes the iron and zinc reaction to intensify.


2. The content of aluminum and other metal elements in the zinc liquid is low, and for active steel and other materials galvanizing, the iron-zinc reaction cannot be effectively suppressed.


3. The increaseed iron content in the zinc liquid deteriorates the quality of the zinc liquid.


Improvement measures:

1. According to the material, choose the appropriate galvanizing temperature;

2. Adjust the composition of zinc liquid to control the content of aluminum and nickel in an appropriate range;


3. Shorten the zinc immersion time as much as possible;


4. Add water as soon as possible to cool down after out of pot;


5. Purify the zinc liquid in time to ensure the quality of the zinc liquid.