ABSTRACT
The bainite reaction, though not yet so named, first came to the general attention of physical metallurgists upon the publication of the seminal paper ‘‘Transformation of austenite at constant subcritical temperatures’’ by Davenport and Bain [1]. As the last of the major reactions through which austenite can decompose to be identified, the bainite reaction has fared hand in the literature in the sense of being unable to develop a logical and stable identity. There are now three clearly distinguishable definitions of bainite (plus many variants of each), which, as we shall show, often refer to quite different phase transformation phenomena. With steel serving as the prototype system for most phase transformations, this confusion has spread into analogous reactions in nonferrous alloy systems with even more disastrous results. In the following discussions, we shall first outline briefly each of the three major definitions, then discuss two key issues of metallurgical substance, and finally arrive at a recommendation as to how each of these definitions should be treated. The following are useful general references on the bainite reaction and provide an entrée to the literature of specific papers: Hehemann, ‘‘The bainite reaction’’ [2], Aaronson, ‘‘On the problem of the definitions and mechanisms of the bainite reaction’’ [3], Hehemann, et al., ‘‘A debate on the bainite reaction’’ [4], and Hehemann and Troiano, ‘‘The bainite transformation’’ [5].
