Can I use rectified AC current to heat an object inside a induction coil?
What you are really trying to do is add DC bias current so that the coil current never has a zero crossing. This is misguided. The losses in the coil are basically entirely resistive, and will be a function of the RMS current. Adding DC bias to the AC current will only increase the dissipation in the coil without increasing the heating in the work piece. The work piece in an induction coil is actually like a magnetic core. Any hysteresis loss which occurs in the work piece helps you attain your goal of heating up the work piece. Hope this is clear.