This process involves heating the part above the upper critical temperature and then air cooling outside the furnace to relieve residual stresses in a gear blank, for dimensional stability. The benefits of normalizing are often achieved from both a thermal and microstructural standpoint. In the thermal sense, normalizing is austenitizing followed by cooling in still or slightly agitated air or nitrogen. In a microstructural sense, normalizing produces a more homogenous structure. A normalized part is very machinable but harder than an annealed part. Normalizing also plays a significant role in the control of dimensional variation during carburizing. NATIONAL HEAT TREAT has 2 furnaces capable of the normalizing process.