2 TIG Welding Copper Nickel Alloy Part 2 of 5
Channel: coppervideo
Date: 2014-04-07

The Copper Development Association is pleased to present a series of video presentations covering the welding of the copper-nickel alloy. This video is the second in a series designed to provide welders with the principles of joining 90-10 and 70-30 engineering grades of copper-nickel. Here we consider TIG welding.

To recap, in our first video, we covered preparation for welding.

- Maintain a high level of cleanliness and avoid contamination which can cause weld cracking
- Preheat and post weld heat treatments are unnecessary

We are assuming that all viewing this video are familiar with the basics of welding and our message is to point out where the copper-nickel alloys are different and exceptions are needed.

Direct current electrode negative is the welding current used for TIG welding of copper nickel alloys. The welding power source should have a down-slope or current decay as well as a lift or high frequency start to minimize defects at the start and end of each pass.

The tungsten electrode used for TIG welding copper-nickel can be the same as the one used for welding other alloys such as stainless steel or nickel alloys.

The end of the electrode is beveled by always grinding it in the longitudinal direction. The grinding should be done on a grinding wheel dedicated to tungsten electrodes to prevent contamination.

The filler metal used for welding both the 90-10 and 70-30 alloys is the 70-30 alloy. In making any copper-nickel weld it is good practice to always add filler metal when possible to provide an optimum weld composition.

The shielding gas for gas tungsten arc welding of copper-nickel is 100% argon. The cup size should be as large as practical provided it does not interfere with welder visibility. A gas lens often improves the gas protection and can allow extending the electrode for welding in areas of tight access.

The torch should be held to about a 15º angle back from the direction of travel and filler metal about 90º from the torch or 15º off the work piece. Tilting the torch to a much greater angle tends to reduce the shielding gas protection and the filler metal should always be held within the inert gas shield area. If the filler metal end becomes oxidized, the end should be cut off.

Visually inspect the weld contour and look for defects such as cracks, undercut, or lack of fusion.

In addition to this video presentation there is also free printed literature covering all aspects of fabrication, welding, corrosion resistance and other subjects of help to all involved with the alloys. We invite you to visit www.coppernickel.org or contact jim.michel@copperalliance.us to access this literature.