I hate to be a master of the obvious, but what could be better for bonding steel to steel than steel - is welding possible?

If not, many epoxy products are available that may meet your requirements.  You will have to contact the manufacturers to determine which product is right for you.

Just a few you might try:

ITW-Devcon
Sika
Fosroc

~dison

Thanks for the suggestions, but we'd rather not weld!  We're looking to secure a joint consisting of a medium-radius (50-60+mm) screw thread with mating faces.  Ideally, we'd like to just coat one part and screw them together - maybe this is over-optimistic?  

Steve.

What you would like to do doesn't sound overly optimistic.  In fact if it's on the small scale that I imagine from your second post, it may not even be all that expensive.

There are epoxy adhesives that are specially formulated for bonding steel surfaces and are heat and impact resistant.

If you contact one of the manufacturers in my first post or simply search for epoxy manufacturers on the internet, you will get some good information on what's available for you to use.

~dison