What is the high temperature resistance of Q345B steel plate

The melting point of zinc is 419.5℃ and the physical properties are cheerful. In the air at room temperature, a thin and high-density basic zinc carbonate film is formed on the surface, which can block further air oxidation.

When the temperature reaches 225°C, zinc is strongly air-oxidized, showing white active zinc oxide. After high temperature baking, the chemical substance of the anti-corrosion layer of the Q345B steel plate is oxidized by air, so the Q345B steel plate cannot withstand high temperature. The surface of the Q345B steel plate will change color after heating, or the surface layer of other chemical substances with protective power will easily turn yellow after air oxidation.

The surface layer of Q345B steel plate should be removed from oil stains or fruit wax components, as well as its dirt or smoke, so as to improve the adhesion of the putty.

Theoretically, it is not recommended to make veneer paint or inner build on the surface of the similar Q345B steel plate that is too smooth. If necessary, it should be corroded (such as sulfuric acid) to improve the compressive strength of the bond with putty and paint.