Soldering is normally done using something like lead or tin - which melt at a fairly low temperature (I vaguely remember it is around 188 degrees C with the soldering iron temperature about double that). Brass requires much more heat and the use of a (gas) brazing torch, at around 450 degrees C. Dunno about chrome, although I've used nickel rods for brazing cast iron in the past (similar appearance to chrome) - anyone in the know? Didn't think you could braze chromium.
BTW if my temperatures are wrong, I apologise, they are from hazy recollections of more than 30 years ago when I was taught, however I've just finished doing some copper pipework this morning (Yorkshire fittings, so solder with a brazing torch) so at least I know HOW to do it if not bthe absolute physics :lol:
I think the question has to be, what are you trying to join?
Scrit