Chapter 9: Carburizing
Gas (atmosphere) carburizing is the de facto standard by which all other surface hardening techniques are measured and is the emphasis of this chapter. Initially, the chapter describes the process and equipment for gas carburizing. This is followed by sections discussing the processes involved in quenching, hardening, tempering, recarburizing, and cold treatment of carburized and quenched gears. Next, the chapter reviews the selection process of materials for carburized gears and provides information on carbon content, properties, and core hardness of gear teeth. The problems associated with carburizing are then covered, followed by the processes involved in heat treat distortion and shot peening of carburized and hardened gears. Information on grinding stock allowance on tooth flanks to compensate for distortion is also provided. The chapter further discusses the applications of carburized and hardened gears. Finally, it reviews vacuum carburizing and compares the attributes of conventional gas carburizing and vacuum carburizing.