Many engineering components require high strength and wear resistance properties in certain areas, while concurrently providing acceptable high ductility and fracture toughness properties in other areas. A common example, from the automotive industry, is a wheel bearing package with integral mounting flange for bolting to the steering knuckle [1]. High strength and wear resistance properties are required in the bearing raceway areas, while high ductility and fracture toughness properties are essential for the flange portion. This objective can readily be accomplished by proper selection of thermal treatment processes. Typically, the forged component is given an initial thermal treatment to establish the desired bulk properties in the forging. Subsequently, a selective hardening process is used to provide the high strength and wear resistance in those areas requiring these properties. The most commonly used thermal treatment processes are; one, a normalizing treatment which results in a pearlitic microstructure, and two, a quench and temper treatment which results in a spheroidized microstructure [2]. A commonly used selective hardening process is induction hardening.
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