Speaker
Alessandro Ferraiuolo
(Marcegaglia Ravenna)
Description
This paper presents the results of the development of an innovative methodology for the online measurement of austenite fraction formed during intercritical annealing in HDG lines. The approach is based on the definition of the analytical equation (Feral equation) relating the austenite fraction formed at soaking temperature with the epitaxial ferrite growth occurring during the reverse austenito-to-ferrite transformation on cooling. Following this approach the annealing cycle in HDG or CAL could be described by three parameters: soaking temperature, soaking time and austenite fraction. This allow to achieve products with exceptional uniform tensile properties and at the same way guarantee the best annealing process efficiency. Laboratory tensile tests and metallographic investigations confirmed a good agreement with the online structure-properties characteristics calculated with the developed mathematical model.
Keywords
Online tensile properties, epitaxial ferrite, online austenite fraction measurement, online grain size measurement, skin pass.
Author
Alessandro Ferraiuolo
(Marcegaglia Ravenna)