Lock in the Transformation

The hardening process involves heating steel or iron above a critical temperature and then holding it there long enough for molecular transformation to occur. The material develops a higher level of hardness when it is cooled at a rate fast enough to lock in the transformation. That critical temperature, referred to as the austenitizing temperature, can range from 750 degrees to almost 1,500 degrees F depending on the grade of carbon, alloys and tool steels.