tig welding cast

By cidme Date 08-18-2003 23:35

i am trying to tig weld a cast iron water pump housing, the problem i am having is when the weld pool melts its gets terribley pourous no matter how much rod i feed into it. has anyone ever seen this? I have a clean weld area and proper sheilding gas, but its still full of porosity, i had similair problems trying to do it with stick also.....any suggestion from a veteran?

By TimGary (****)

Date 08-19-2003 12:14

Is there any chance that your cast iron is actually pot metal?
It sounds too me like you are fighting impurities in the base metal itself...

Tim

By Niekie3 (***)

Date 08-19-2003 13:53

Hi cidme

I must agree with Tim, that you have some kind of contamination present. Either the base metal is just a very "dirty" casting, or your casting has experienced some preferential corrosion. If the pump has been in service for a long time, then it is possible that the material has experienced preferential corrosion of the ferrite phase, leaving a somewhat porous structure of graphite. This can typically be seen if the material seems to just "vapourize" when you strike the arc. When this has progressed very far, then welding is impossible. The material just dissappears and does not melt.

At any rate, if you have contamination, using SMAW should work better than GTAW. Especially if you use an ENi-CI electrode

Regards
Niekie Jooste
Fabristruct Solutions