Open AccessEffect of two-step ausforming on bainite transformation and retained austenite in a medium-carbon bainitic steel
Author(s) -
Guanghui Chen,
Guang Xu,
Henry Hu,
Junyu Tian,
Qing Yuan,
Jun Wang
Publication year - 2020
Publication title -
materials research express
Language(s) - English
Resource type - Journals
ISSN - 2053-1591
DOI - 10.1088/2053-1591/ab61b7
Subject(s) - bainite , austenite , materials science , isothermal transformation diagram , metallurgy , isothermal process , scanning electron microscope , transmission electron microscopy , strain (injury) , microstructure , composite material , nanotechnology , medicine , physics , thermodynamics
It is commonly accepted that single ausforming with small strain at low temperature promotes isothermal bainite transformation and leads to more retained austenite. In the present study, the effects of two-step ausforming on the bainite transformation and retained austenite in a Fe-C-Mn-Si medium-carbon bainitic steel were investigated by thermo-mechanical simulator, x-ray diffraction, scanning electron microscope and transmission electron microscope. The results show that the two-step ausforming cannot further promote the bainite transformation compared with single ausforming. However, the two-step ausforming enhances the mechanical stability of residual austenite due to more dislocations induced by the second deformation and therefore leads to more retained austenite. In addition, when the total strain is constant, the fraction of retained austenite increases with the increasing second strain. Moreover, the thickness of bainite plates treated with two-step ausforming is larger compared with single-step ausforming when the total strain is the same.