Heat-treatment for ferrous alloys in which a part is quenched from the austenitizing temperature at a rate fast enough to avoid formation of ferrite or pearlite, and then held at the to achieve the desired characteristics. Austempering at lower temperatures (240° C to 270° C) produces a part with maximum strength, while austempering at higher temperatures (360° C to 380° C) yields high ductility and toughness.appropriate transformation temperature