SPHEROIDIZING. Heating and cooling to produce a spheroidal or globular form of carbide in steel. Spheroidizing methods frequently used are:
- 1. Prolonged holding at a temperature just below Ae1.
- 2. Heating and cooling alternately between temperatures that are just above and just below Ae1.
- 3. Heating to a temperature above Ae1 or Ae3 and then cooling very slowly in the furnace or holding at a temperature just below Ae1.
- 4. Cooling at a suitable rate from the minimum temperature at which all carbide is dissolved, to prevent re-formation of a carbide network, and then reheating in accordance with method 1 or 2 above. (Applicable to hypereutectoid steel containing a carbide network.)
