Some Aspects of the Pearfite Reaction - R. F. Mehl's Analysis

摘要

The three fundamental units of the pearlite reaction are the pearlitic lamellae of ferrite and cementite, pearlite colonies and pearlite nodules. The development of colonies and npdules, primarily in eutectoid steels, is discussed in terms of the theories of Mehl and co-workers. According to Mehl, colonies consist of alternate, predominantly parallel, plates of ferrite and cementite. These colonies form at the pearlite initiation stage. Subsequent growth, however, involves the development of pearlite nodules, which are comprised of several pearlite colonies. The terms uni-nodule, bi-nodule and group nodules are reintroduced. The decomposition of austenite via these three entities is related to the transformation temperature, which controls both the nucleation and growth rates of the pearlite colonies.