What is the reason for the brown oxide film after the light treatment?

After light treatment, under normal circumstances, it will not be severely oxidized within a short time. If the brown oxide film appears, it may be smouldered by alkaline mist. If there is a local phenomenon, it may be in contact with alkaline solution.

The above-mentioned artifacts, if the subsequent process is grinding, polishing, sandblasting or anodizing can be carried out as usual, without reprocessing, otherwise you must re-alkaline corrosion, re-light treatment, otherwise unable to weld, can not be chemical conversion film processing .