Metal spraying and welding are totally different processes despite what an ill-informed Wikki ego posted.
Ok, maybe not the right terminology here. Strictly speaking, welding is the joining of two metals by the aid of a third (which can be three times the same metal), so in a sense the phrase " building up with weld" ain't right either...
In both processes the aim is to get the one metal to bond with the other by the aid of heat. Can we thus agree on using the word "fusion" maybe?
Well if this was a conversation down the pub, I would not give a wrinkled rats rectum about correctness,
However this is a conversation in cyber space and as such it will persist forever.
Even worse it is searchable and indexed so others will also find the wrong answers and thus an urban myth is born.
The defining thing about a weld is not how it is made.
It is the fact that the microstructure is
CAST becuse all parties to the process are at some point in time were
MOLTENThe one and only exception to this is vacuum welding where neither pars get particularly hot and the microstructure of both parts is unchanged.
By definition flame spraying is a
BRAISING process because the parent material is not molten at any time but the filler ( or build up material if you like ) is molten.
Thus the parent material more or less retains the microstructure that it had before the process