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Discoloration of anodic film after welding

I am a quality technician working in a company that manufactures Aluminum doors, frames and curtain walls. recently we are facing a problem with discoloration on 17 and 14 finish jobs AFTER welding (we need to anodize profiles and then cut and weld them). the pattern looks like spider web originating from welded area. Nothing has changed in our welding department and profiles passing Seal test and anodizing thickness test so I am confused as why is this happening. I would appreciate it if any one can help me in this matter.
thanks,

Yasha Beydokhti
Employee - Scarborough, Ontario, Canada
July 7, 2008

The anodic coating cannot withstand the high temperature of welding. Cracking starts somewhere around 80 to 100 C, depending on the alloy and anodic thickness.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

July 10, 2008

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