Drilling and tapping is the best bet, I’d say. Should you wish to
Main problem with your plan is to keep the steel component ready for
fusion over the period it takes to heat it to that temperature. I
have found also that the flux that would normally protect the steel
from oxidation is ‘used up’ over that period, with no hope of
topping up due to the closed nature of the investment void. I have
noticed that the investment dissolves in the flux at casting
temperature thus loosing the fidelity of the shape being cast. You
could try tinning the embedded end of the stud or screw with layer of
bronze or silver solder. This would give you a fusion bond with the
steel and (erm…hopefully) the incoming casting metal could have a
greater change of bonding with the tinned surface than the original
steel. Now I want to go try this out myself!
However, I have fixed steel screws into aluminum castings for the
same purpose and have found that if you arrange to cast round the
head of a machine screw, preferably csk slotted, the shape of the
head is enough to form a mechanical key with the surrounding
aluminum matrix. There is little or no chance of a fusion bond
between aluminum and steel with my set up. This will at least cut out
the need for crosswise drilling of the stud.
Similarly, I have attached aluminum castings to a larger mixed metal
component using steel nuts welded/brazed edgewize to form loops
through which the incoming casting alloy flows.
admittedly the result is a bit heavy handed!
I have spent many years casting copper alloys around steel
component, and have just uploaded some pictures of work with embedded
screws. I use these as purely decorative shapes. No business end
poking out though!
The way I have affixed screws to the back of bigger metal objects to
be mounted is to use a flat topped csk screw. There is enough area on
the top surface of the screw to allow for a silver solder bond
between screw and object. Maybe this would not be strong enough for a
high load job like a cabinet handle.