The iron oxide skin on surface of GB/T 1591 Q345B structure steel plates

The iron oxide skin on surface of GB/T 1591 Q345B structure steel plates are mainly produced in the laminar cooling process and in the roughing and finishing regions. The iron oxide skin can be a mixture of two times of iron oxide and three times of oxide scale. The two oxide scale is mainly produced in rolling process during rough rolling area, which requires temperature control. If the RT2 temperature is too high, it will produce too much surface of GB/T 1591 Q345B structure steel plates.

If the allocation of high pressure water and phosphorus removal water in rough rolling area is well adjusted, the production of two times oxide scale can be suppressed by adjusting the outlet temperature of rough rolling. The outlet temperature of rough rolling is controlled at 990 ~ l010 C. Three iron oxide is produced in the finishing area of the GB/T 1591 Q345B structure steel plates billet between the temperature of 1000 DEG to 1070 DEG C, after finishing high pressure water descaling, the Q345B structure steel plates billet temperature drop to 40~60 DEG C, which means a lot of steel entering finishing mill in the temperature of 1000 degrees Celsius, while the final rolling temperature generally at 820~890 DEG C. Therefore in the rolling process of GB/T 1591 Q345B structure steel plates, the three time iron oxide skin is very easy to form. And the cooling water between stands becomes very important, it will inhibit the three iron oxide production.