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Subject: Re: Welding Molybdenum
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Date: 06/14/02 at 8:41 AM
Posted by: Steve U.S. Alloys
In Reply to: Re: Welding Molybdenum posted by Rick on 06/14/02 at 7:22 AM:
You are absolutely correct, Rick. I misread the request.
Pure Moly is handled in much the same way as tungsten. It really should be joined in a high purity atmosphere after an involved chemical cleaning process. Hot air drying is recommended upon completion of the cleaning process. If it is to be TIG welded, run off tabs should be utilized to prevent crater cracking at the end of each pass during welding. DCEN polarity is used and heat input is kept to a minimum. After welding, the material can be stressed relieved to restore ductility. Post grinding to remove bead ripples and surface contaminants will also help restore ductility. If pure Mo is welded out in the open atmosphere, nitrogen and oxygen can be absorbed in quantities sufficient to cause brittleness in the HAZ and subsequent joint failure.
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