Phase Equilibrium and Austenite Decomposition in Advanced High-Strength Medium-Mn Bainitic Steels

Metals

Adam Grajcar¹  Aleksandra Kozłowska¹  Wojciech Burian²  Władysław Zalecki² 

[1] Faculty of Mechanical Engineering, Silesian University of Technology, 18a Konarskiego Street, Gliwice 44-100, Poland;Institute for Ferrous Metallurgy, 12-14 K. Miarki Street, Gliwice 44-100, Poland;

关键词: medium-Mn steel;    austenite decomposition;    dilatometry;    phase equilibrium;    retained austenite;   

DOI  :  10.3390/met6100248

来源: DOAJ

【 摘 要 】

The work addresses the phase equilibrium analysis and austenite decomposition of two Nb-microalloyed medium-Mn steels containing 3% and 5% Mn. The pseudobinary Fe-C diagrams of the steels were calculated using Thermo-Calc. Thermodynamic calculations of the volume fraction evolution of microstructural constituents vs. temperature were carried out. The study comprised the determination of the time-temperature-transformation (TTT) diagrams and continuous cooling transformation (CCT) diagrams of the investigated steels. The diagrams were used to determine continuous and isothermal cooling paths suitable for production of bainite-based steels. It was found that the various Mn content strongly influences the hardenability of the steels and hence the austenite decomposition during cooling. The knowledge of CCT diagrams and the analysis of experimental dilatometric curves enabled to produce bainite-austenite mixtures in the thermomechanical simulator. Light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to assess the effect of heat treatment on morphological details of produced multiphase microstructures.

【 授权许可】

Unknown