Modelling of the dynamic recrystallization of austenite in low alloy and microalloyed steels

• Published in: Acta materialia Vol. 44; no. 1; pp. 165 - 171
• Main Authors: Medina, S.F., Hernandez, C.A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.1996; Elsevier Science
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Deformation, plasticity, and creep; Exact sciences and technology; Materials science; Metals. Metallurgy; Physics; Treatment of materials and its effects on microstructure and properties; Grain size; Temperature range 1000-4000 K; Microalloyed steel; Torsion test; Austenite; Mechanical properties; Dynamical recrystallization; Low alloy steels; Microstructure; Modeling; Flow stress
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/1359-6454(95)00154-6

Using torsional tests in the austenite phase, the dynamic recrystallization of a selection of low alloy and microalloyed steels was studied and Avrami's equation was modelled. The model is based on the experimental determination of flow curves and their subsequent modelling, making it possible to calculate the recrystallized fraction (Xd) as a function of all the variables which intervene in hot deformation: temperature, strain rate, austenite grain size and the chemical composition of the steel. The influence of the first three variables is quantified using the Zener-Hollomon parameter where the activation energy is expressed as a function of the content of each alloy. The start of dynamic recrystallization was determined by regression, finding a value of 0.95ϵp. In testing conditions all the elements were found in solution in the austenite, except Ti which was found partially precipitated. The results of these tests indicate that C, Si (low content), Mn and V have hardly any influence on the start of recrystallization while Mo, Ti and especially Nb delay it. Finally, the dynamic recrystallization kinetics are illustrated through the study of the microstructure during deformation.