Abstract
The rate at which austenite decomposes to form ferrite, pearlite and bainite is dependent on the composition of the steel, as well as on other factors such as the austenite grain size, and the degree of homogeneity in the distribution of the alloying elements. Allotriomorphic ferrite is the first phase to be generated at all temperatures. In the lower temperature range the Widmanstetten ferrite is formed, while on higher temperatures grain boundary allotriomorphs are produced. The present paper is concerned to the experimental study of the isothermal decomposition of austenite in allotriomorphic ferrite in a modern medium carbon vanadium–titanium micro alloyed forging steel. This paper deals with the isothermal austenite-to-allotriomorphic ferrite as a whole, considering the specific role of different features such as prior austenite grain size (PAGS) and isothermal temperature, in nucleation and growth processes independently.