Like Chip says 4043 or 5356, yet it is recomended to use 4043 on castings and 5356 for structural aluminum. Yet I have used both in trying to get a better weld. First I clean with solvent or I wire wheel castings and then heat entire casting to a few hundred degrees or so. If first weld is quite porous , I'll wire wheel the black off or even cut out weld and go at it again. At times on a porous aluminum it will take two attempts to get a good weld for the first may just burn out the impurities in the base metal, then the second pass will or should cover much better.
Last edited by Jerry; 08-14-2003 at 01:25 PM.
J P Streets Welding LLC