Influence of the prior athermal martensite on the mechanical response of advanced bainitic steel

Navarro Lopez, A.; Hidalgo Garcia, J.; Sietsma, J.; Santofimia, Maria Jesus

doi:10.1016/j.msea.2018.08.047

Influence of the prior athermal martensite on the mechanical response of advanced bainitic steel

Title

Influence of the prior athermal martensite on the mechanical response of advanced bainitic steel

Author

Navarro Lopez, A. (TU Delft (OLD) MSE-1)
Hidalgo Garcia, J. (TU Delft (OLD) MSE-3)
Sietsma, J. (TU Delft Materials Science and Engineering; TU Delft (OLD) MSE-3)
Santofimia, Maria Jesus (TU Delft (OLD) MSE-3)

Department

Materials Science and Engineering

Date

2018

Abstract

The accelerated formation of bainite in presence of martensite is opening a new processing window for the steel industry. However, for a feasible industrial implementation, it is necessary to determine the mechanical behaviour of the steels developed under such conditions. This study focuses on analysing the effects of the formation of athermal martensite, followed by the formation of bainitic ferrite, on the mechanical response of a low-C high-Si steel. For this purpose, microhardness measurements and tensile tests have been performed on specimens that were thermally treated either above or below the martensite-start temperature (M_s). Specimens isothermally treated below M_s exhibit a good combination of mechanical properties, comparable with that of the specimens heat treated by conventional treatments above M_s, where there was no prior formation of martensite. Investigations show an increase of the yield stress and a decrease of the ultimate tensile strength as the isothermal holding temperature is decreased below M_s. The formation of prior athermal martensite and its tempering during the isothermal holding leads to the strengthening of the specimens isothermally heat treated below M_s at the expense of slightly decreasing their strain hardening capacity.

Subject

Bainitic ferrite
Isothermal treatments
Mechanical response
Multiphase steels
Prior athermal martensite
Strengthening mechanisms

To reference this document use:

http://resolver.tudelft.nl/uuid:cd79ea94-7654-401e-9504-d7db73093a9e

DOI

https://doi.org/10.1016/j.msea.2018.08.047

ISSN

0921-5093

Source

Materials Science and Engineering A: Structural Materials: Properties, Microstructures and Processing, 735, 343-353

Part of collection

Institutional Repository