Hello Mazdadrags, I have done a certain amount of welding on bronze impellors for various chemical pumps using the GTAW process. As I remember, we used either silicon bronze tig rod or silicon aluminum bronze fillers, don't remember the specific alloys or id numbers for these. Used straight argon and polarity was DCEN, also as with most other GTAW welding, clean, clean, clean, the welding area you are working on. Don't recall using any preheat in these particular instances. Would experience some centerline cracking at times, in most cases could make this go away by trying different fillers until the most correct match was found. Regards and good luck, aevald

I have some experience on this, using both ER CuAl-A2 and ERCuSn - A/B/C rods,
Success in welding zinc brasses is mainly determined by zinc content, u should expect serious porosity problems when Zn>30%,
anyway tipical configuration is DCEN and 100% Argon shielding gas, 2% thoriated tugnsten. Argon-25%He its supposed to work well
in heavy sections but i never tried it. To avoid porosity try to work with the lowest possible amperaje, but with zinc to high is almost certain
you will get pores.
Aluminium brasses and orher low zinc brasses are more easily welded