a method is disclosed for heating a cold worked sheet of superplastically formable metal composition to recrystallize its microstructure to a suitably formable condition and further to heat the sheet to a temperature for an immediate forming operation . the method utilizes a combination of hot air convection heating and infrared radiation to rapidly accomplish the heating . high temperature infrared heating elements provide most of the energy during an initial high heating rate phase and then those elements are shut off and heating is completed with controlled temperature hot air to prevent overheating of the sheet metal .