Posted by Rick The Cu / Ni alloys are usually easily welded with either GTAW "TIG" or SMAW "Stick" with TIG being the preffered method. However caution must be taken because thes alloys are suseptable to "hot cracking" after welding and a filler metal with sufficient deoxidizers and or desulpherizers must be used. Manganese is most often used for this purpose.
on 1/4/2006, 2:47 pm, in reply to "Cu-Ni Pipe welding"
216.108.4.72
Leroy
The "hot cracking" can be greatly minimized by #1: Reducing contraint during welding. #2: Preheat to reduce the stresses and retard the cooling rate approx. 250 F. for 1/4" thickness. #3: Reduce the root opening and increase the size of the root pass itself.
he SMAW "Stick" electrode most commonly used for this application is ECuNi and is approx. 70% Cu and 30% Ni. This rod will run about 30% hotter than a regular carbon electrode.
The TIG filler metal will be ERCuNi and is approx. 98% Cu with some ther goodies added for the deoxidizing etc. You can use Argon for thin sections 1/8" but use 75/25 heliun Argon for anything thicker than 1/8".
Hope some of this helps.
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