The T-bend performance reduction is the initial color coated steel coil performance of the metal corrosion under the coating. At this time, there won’t have coating blister or fall off phenomenon if only observe from the surface. But the T-bend performance reduction has shown that the metal corrosion under the coating has already begun to happen.
This is because the coating does not have any internal density unevenness, micropores, cracks and gaps and other defects. And in the environment medium still exists the transmission channel that the outside media infiltration can permeate.
During the related experimentation, NAMKIM STEEL found that the water molecules in coating surface can reach the coating metal matrix interface through the adsorption, diffusion, infiltration and other effects, until caused the destruction of coating bond interface.
The initial macroscopic manifestation of this interface’s destruction may be the decrease in coating adhesion. Color coated steel coil performance is the poor coating adhesion timeliness. And its further macroscopic performance is the coating blistering, shedding and so on.
Therefore, the corrosion resistance of the color coated steel coil can be predicted by the experimental results of the adhesion aging performance.
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