A piece of 1" red oak can be bent to radius of 1" if supported by a
metal strap and 11.5" unsupported according to "wood Bending Handbook"
published by Woodcraft Supply. That sounds about right to me as long
as the strap is fixed at both ends so that the neutral axis is pushed
to the outer radius. Also, remember that it is primarily the heat that
plasticizes wood and that you do not gain any additional softening by
heating the wood beyond the boiling point of water. Luthiers use dry
heat as did barrel makers. I have never had very good results from
simply getting the work piece wet, it must get hot.

If you need to do further testing for your application before building
a steam box you can try boiling the piece of wood or wrapping the
section that you need to bend in rags and pour lots and lots of
boiling water over the rags.

Leverage helps but does not prevent breaking or crushing the grain on
the inner radius. Bending over matched male and female forms with
plenty of clamps does help.