WELDING OXYGEN FREE COPPER

By robbiehilton Date 04-03-2003 19:49

We are trying to make a tube from oxygen free copper UNS C10200. The material thickness is .0055". The weld seam is cracking in the HAZ and the cross sectional area shows that not all of the metal is being melted. The gases used are He and Ar. After this tube is made, an expansion joint will be punched out of this tube.

Can this weld seam be cold work to help the properties?
What would the maximum weld gap be to produce a good weld seam?
Are there any annealing processes to help the grain structures.

By Niekie3 (***)

Date 04-07-2003 19:53

Hi

This material you are welding is very thin. I have never been involved in welding copper this thin. Are you sure it is not maybe 0.055"?

At any rate, with such a thin material you would not typically need any gap or weld prep. Also, no pre-heat would generally be required. In general you should have little problem welding oxygen free copper, unless it has been exposed to elevated temperatures for some time, because then it could have absorbed some oxygen.

Annealing would rarely be required, but you can anneal at 700 - 1200°F for 15 - 30 minutes. At the higher temperatures, grain growth will become a problem.

Hope this helps

Regards
Niekie Jooste