Kpanand,

Welcome to ArtMetal.

I may have some ideas to share with you but all the acronyms don't tell me anything so I'm not sure. What is WCC? I'm assuming that PWHT means Post-Welding Heat Treatment, correct?

You do not say what metal you are casting, unless the WCC indicates something I'm not familiar with.

If you're casting brass or other copper alloy, the welding will boil off some of the alloying metals with lower melting points and this causes color changes. No cure for this that I know, other than plating. You have to experiment with different alloys for your filler metal until you get one that yields the correct color match - however, that color may match after polishing but not after patina or aging, because the filler may react differently than the base metal.

Rich

It may be helpful to add what types of defects were revealed by the radiography and why your application required the repair. If the repair was for techinical reasons (mil spec for example), then color matching may not be possible if certain characteristics are needed. If the repairs were needed to cober up a casting defect then maybe you should pursue the caster for a redo.

With sculptural castings, metal color matching is imperative and this is the reason I use ONLY EVERDURE. There is no lower temperature alloying metals other than copper and silicon (at least in any amounts that create a color variation). Many if not most brasses have a larger number of different alloying metals within the alloy mix, many and again if not most, are lower melting (thus fuming) temps. and tend to burn off to a certain degree upon welding. Sometimes "special" welding rod materials are available with additional "burn off" alloys added to "make up" for the burn off loss and to give a better base metal/filler metal match.

So for this sort of item, one must make sure there is some sort of filler that can be used that will match the parent metal after welding. Otherwise, recast with an appropriate metal that has a filler material that will match the base metal AFTER the weld is made.