Methods of producing friction elements

摘要

A vehicle brake drum or clutch plate is made by cold forming a steel blank which has previously been annealed to convert at least 75% of the cementite content of the steel to spheroidal form. The steel includes 0.6 - 0.88% combined carbon and is initially pearlitic in structure and in the form of rolled sheet stock. In an example, SAE 1080 steel strip having 0.80% carbon content and of 0.58 cm thickness is heated at just below the transition temperature of 732 DEG C. until the desired amount of cementite is spheroidized.