Microstructure evolution of medium‑manganese Al-alloyed steel manufactured by double-step intercritical annealing: Effects of heating and cooling rates

Kozłowska, Aleksandra; Morawiec, Mateusz; Petrov, R.H.; Grajcar, Adam

doi:10.1016/j.matchar.2023.112816

Microstructure evolution of medium‑manganese Al-alloyed steel manufactured by double-step intercritical annealing

Title

Microstructure evolution of medium‑manganese Al-alloyed steel manufactured by double-step intercritical annealing: Effects of heating and cooling rates

Author

Kozłowska, Aleksandra (Silesian University of Technology)
Morawiec, Mateusz (Silesian University of Technology)
Petrov, R.H. (TU Delft Team Maria Santofimia Navarro; Universiteit Gent)
Grajcar, Adam (Silesian University of Technology)

Date

2023

Abstract

A novel double-step intercritical annealing (DSIA) process was conducted on Fe-0.16C-4.7Mn-1.6Al-0.2Si transformation induced plasticity (TRIP) steel. In a present study, an effect of different heating and cooling rates applied to the second intercritical annealing (IA) step on the microstructure was studied in detail by using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) techniques. The quantitative analysis of the retained austenite fractions for particular heat treatment variants was carried out via X-ray diffraction (XRD). The formation of complex microstructures containing a small fraction of ferrite, retained austenite and two types of martensite was observed regardless on the applied heating and cooling rates. It was found that the soft ferrite can be replaced by martensite through the incomplete stabilization of austenite with C and Mn during short second intercritical annealing step. The heating rate influences significantly the kinetics of austenite formation during the second heat treatment step. Low heating rates ensure more time for formation and homogenization of austenite during heating improving its thermal stability. Thus, the best balance of martensite and austenite fractions in combination with homogenous morphology of the microstructure was noted for the specimen heated at a rate of 3 °C/s, which was the lowest one in the reported experiment.

Subject

Double-step intercritical annealing
Low-C martensite
Medium-Mn steel
Multiphase microstructure
TRIP-assisted steel

To reference this document use:

http://resolver.tudelft.nl/uuid:6812f5d8-6a4b-4d21-94d2-ab3a861f0460

DOI

https://doi.org/10.1016/j.matchar.2023.112816

ISSN

1044-5803

Source

Materials Characterization, 199

Part of collection

Institutional Repository