Trying to solder to chrome

A. I do not think that you will achieve decent results soldering to chrome. You might be able to develop a crimp fitting, but I would switch to electroless nickel which will solder, looks good and has better corrosion resistance.

A. Ernst

If I wanted to guarantee that solder would not stick, chrome plating would be high on my list.
You may have some success with a flux designed for stainless steel but I would not put money on it.
The other thought that strikes me is that in many years in printed circuit plating, I have never met chrome on a PC.
Unless there is a pressing need, you may be better off with nickel plating - not easy to solder, but a great deal easier than chrome.
Don't forget that the aggressive fluxes need careful removal after soldering or you are inviting corrosion problems.

A. Use a solution of zinc chloride as a pre solder flux. To make zinc chloride; get muriatic acid (HCl) and put some galvanized items in it, like nails, screws, boat anchor chain. Let the acid dissolve the zinc which is zinc. The solution should turn yellow. Apply the solution to the parts needing soldering, then apply solder.