How to do chrome plating on "Inconel" ( 70%Ni w/Ferrous and 18% Cr)?

A. It is not as tough as plating on waspalloy or incolloy or hastelloy, but it has to be clean and it has to be properly etched. There are a number of different etch makeups listed in numerous publications. I like a dip in a low to mid concentration of nitric-hydrofluoric acid with an excellent rinse and if you are having any problems, a strike in a woods nickel tank, rinse rapidly and immediately into the chrome tank.
Smut is a problem with any process that uses reverse current in the etch tank, but you can find an ideal voltage and time to overcome that. Did not have much luck with a number of others on high nickel--94%.

A. See ASTM B558, 'Standard Practice for Preparation of Nickel Alloys for Electroplating.' Section 3 gives 4 activation methods, and the Appendix lists the appropriate method for each of 22 Ni-containing alloys. Possibly, your alloy requires an anodic + cathodic treatment in a modified Wood's nickel strike. Separate tanks are recommended (avoids contaminating the cathodic solution). Follow with the appropriate chromium plating procedure (ASTM B650 for hard chromium, ASTM B456 for decorative chromium).

Get the product bulletin for your specific alloy (composition is close to Inconel® X-750 or 751 or NIMONIC® Alloy 80A) from Special Metals: http://www.specialmetals.com/products/index.htm
If heat treating this alloy, also get their 'Fabricating' bulletin. It warns against solutionizing in air, which forms a thick black, difficult-to-remove scale and leaves a depleted alloy surface. Instead, use a slightly reducing atmosphere, inert gas or vacuum.