In the whole hot galvanizing process, another important process except galvanizing is the internal annealing process of the strip.
In strip continuous hot galvanizing technology, through continuous strip annealing to achieve the following two purposes:
(1) complete strip to knot the annealing process, remove the work hardening phenomenon in the process of cold rolling, restore its plastic in order to further process for cold working, heat treatment, at the same time as the final product to control finished product performance and get a different combination of strength and plasticity, produce the different state of hard and soft products;
(2) cool the strip to the temperature of the zinc pot so that the strip has a clean, non-oxide active surface, and seal the strip into the zinc pot for galvanizing.The entire annealing furnace is mainly divided into heating section, heating section and air cooling section.
1. Heating of strip steelThe strip is heated to recrystallization temperature in the heating section.
The heating section is divided into five sections along the length of the furnace.Control the size of gas flow alone. There are two thermocouples in each area, one is used to measure the furnace temperature in the area, the other is used to make overtemperature alarm, when the furnace temperature is too high, automatically reduce the load to prevent damage to the furnace equipment.
Operators can adjust the size of gas supply by setting the furnace temperature in each area, that is, adjust the load in the area. Due to the low strip when I first got into the furnace temperature, from, 1 area run to five area in the process of temperature rising, as a result, from 1 to 5 areas furnace temperature control from low to high, in 1 area due to the strip temperature minimum, so the temperature control to the lowest, and then, in turn, increases, thus ensuring strip annealing treatment according to above annealing curve. It is necessary to balance the load of each zone and try to control the load