Aluminum weld turns black after anodizing

Date 03-06-2012 21:19

the job is aluminum handrail ,TIG welded ,clear anodized finish ,the welds were ground ,
what would cause the weld to turn black after anodizing
could it be that the wrong filler metal was used ,or some other contamination

see the attached photos
thank you
Bill K

By aevald

Date 03-06-2012 21:52

Hello Bill, using an incorrect filler metal. 4043 will turn black, 5356 won't, when anodized. Unfortunately, you are not the first one to find that out. I worked for a local company that had a similar experience. They had to remove all of the welds and re-weld them and then have the anodizing done again. Sorry, best regards, Allan

By 99205

Date 03-07-2012 01:36

Don't feel bad, it happens all the time. I've learned, when it comes to aluminum, ask first.

By jwright650 (*****)

Date 03-07-2012 13:25

Hi Bill,
I know this won't help you now(after the fact)....we have several threads in the forum archives on this very subject. Anyway, keep this in mind for any future quests, might save you some heartache that some of the rest of us have already suffered through in the past.
regards,
JW

By billk63 (*)

Date 03-08-2012 01:44

what i think happened is that some one spilled all the filler wire out of the box and some how got the filler metal mixed up ,half of the weld is ok not black,the other half of the joint is black ,someone got lazy
i am glad this did not come out of my shop ,this was done by a subcontractor of ours

i am new to the forums and think it is agreat tool

thank you all for your help

bill k