Microstructural Evolution of C-Mn Dual Phase Steel During Intermediate Quenching: A Comparative Study of Subcritical, Intercritical, and Upper Critical Annealing

Articles in Press

Document Type : Original Article

Authors

1 Faculty of Materials Engineering, Sahand University of Technology,

2 Department of Materials Engineering, Isfahan University of Technology

3 Faculty of Materials Engineering, Sahand University of Technology

Abstract

Martensitic microstructure, due to providing numerous nucleation sites for austenite, is considered as the initial microstructure in the dual-phase steel fabrication process, i.e. intermediate quenching. In the present study, the microstructural evolution of a carbon-manganese steel during intermediate quenching at three temperature ranges (upper-critical (AC₃<T), inter-critical (AC₁<T<AC₃) and sub-critical (T<AC₁)) was studied using optical microscopy, scanning electron microscopy, and X-ray diffraction analysis. According to the corresponding hardness of different microstructures, it was found that the sub-critical annealing process, the high-temperature tempering process, has two stages with different softening rates. The first stage is associated with the removal of carbon from the lattice structure to form carbides, and the second stage is accompanied by the coarsening of carbides. Annealing martensitic microstructure at intercritical temperatures also shows three stages: The first stage is the tempering of martensite, the second stage is the nucleation and growth of austenite in tempered martensite, and the dissolution of carbides, and the third stage is the coarsening of the two-phase microstructure, which is associated with reduction in hardness. An increase in temperature up to upper-critical temperatures also causes the appearance of these three stages, but considering the intensified diffusion at high temperatures, these stages are shortened and merged together.

Keywords

Main Subjects

Journal of Advanced Materials in Engineering (Esteghlal)

Articles in Press, Accepted Manuscript
Available Online from 13 August 2024

Files

Share

How to cite

Statistics

تحت نظارت وف ایرانی