Do you know why Coated steel is tested for adhesion?

In the daily production process, how to evaluate the quality of color-coated panels, one of the important indicators is the coating adhesion factor.

As far as the current detection methods at home and abroad are concerned, T-bend experiments are mostly used to detect the coating adhesion of color-coated panels. However, the use experience of color-coated plates shows that the coating adhesion of some color-coated plates will deteriorate rapidly with the prolongation of storage time, which affects the normal use of color-coated plates. The most direct manifestation of the coating adhesion and aging performance of color-coated plates is that the T-bend test results of color-coated plates decrease rapidly with the prolongation of storage time. The main factor causing the continuous decline of T-bend performance is nothing more than the influence of water, oxygen and ions in the natural environment where the color-coated board is stored. This effect is a slow process, so it takes a certain amount of time for this effect to occur and can be shown by the T-bend test. This will cause the color-coated sheet to show poor adhesion after reaching the user's hands, which will have an adverse effect on both the color-coated sheet production unit and the user. 

Experiments have shown that the coating adhesion aging performance of color-coated panels is affected by the properties of the coating, the properties of the substrate under the coating, and the performance of the chemical conversion film between the coating and the substrate. The main influencing factors are the coating system and the pretreatment state of the substrate.