Can I use a 220v soldering iron on 110v?
Very likely yes, it will heat up. But it might not get hot enough to do any proper soldering. As the voltage is halved, so is the current. That means the power of 60 W will be divided by a factor of 4 so your 60 W iron will now only behave as a 15 W iron.

There are small soldering irons rated for 15 W so 15 W might be enough for some soldering jobs. It depends on how the iron is build, if it has a lot of metal it might take very long to heat up and/or radiate too much heat to become hot enough for soldering.

Anyway, you can safely try it out, as the mains voltage is lower than the iron's rated value it is safe to try.