Listen to DIGnLIFE he knows what he is talking about. If you have access to a welding supplier see if you can get a TEMP STICK for cast iron. That way you can pre heat to the right temp before you start. If you don't have access to someones asbestos blanket to cover it up to slow down cooling process, you might try using a oven.
Otherwise you are wasting your time and will have junk when you are done.