TY - JOUR
T1 - Unravelling the mechanical behaviour of advanced multiphase steels isothermally obtained below Ms
AU - Navarro-López, Alfonso
AU - Hidalgo, Javier
AU - Sietsma, Jilt
AU - Santofimia, Maria J.
PY - 2020
Y1 - 2020
N2 - The initial formation of athermal martensite was proven to accelerate the subsequent bainite formation kinetics during isothermal holdings below the martensite-start temperature (Ms). The presence of prior athermal martensite (PAM) within the phase mixture is expected to modify the overall mechanical response of these newly-designed multiphase steels. Differences stem not only from the balance of product phases, but also from the effect of tempering of the PAM with variations in the applied holding time. This work investigates the effect of tempering time on the mechanical behaviour of the PAM and, as consequence, on the overall mechanical response of these microstructures. Results show that, for short holding times (several minutes), PAM yields similar to as-quenched martensite while, for longer holding times, its yielding behaviour becomes comparable to the one exhibited by typical tempered martensite. Furthermore, the use of Kocks-Mecking curves for the analysis of the mechanical performance confirms the bainitic character of the product phase isothermally formed below Ms. Tailoring the bainitic-martensitic microstructure with variations of the holding time below Ms enables to obtain advanced multiphase steels with comparable mechanical properties to those exhibited by conventional bainitic steels, but in shorter processing times due to the acceleration of bainite formation.
AB - The initial formation of athermal martensite was proven to accelerate the subsequent bainite formation kinetics during isothermal holdings below the martensite-start temperature (Ms). The presence of prior athermal martensite (PAM) within the phase mixture is expected to modify the overall mechanical response of these newly-designed multiphase steels. Differences stem not only from the balance of product phases, but also from the effect of tempering of the PAM with variations in the applied holding time. This work investigates the effect of tempering time on the mechanical behaviour of the PAM and, as consequence, on the overall mechanical response of these microstructures. Results show that, for short holding times (several minutes), PAM yields similar to as-quenched martensite while, for longer holding times, its yielding behaviour becomes comparable to the one exhibited by typical tempered martensite. Furthermore, the use of Kocks-Mecking curves for the analysis of the mechanical performance confirms the bainitic character of the product phase isothermally formed below Ms. Tailoring the bainitic-martensitic microstructure with variations of the holding time below Ms enables to obtain advanced multiphase steels with comparable mechanical properties to those exhibited by conventional bainitic steels, but in shorter processing times due to the acceleration of bainite formation.
KW - Bainite formation
KW - Microstructure-properties
KW - Multiphase steels
KW - Prior athermal martensite
KW - Tempering
KW - Yielding behaviour
UR - http://www.scopus.com/inward/record.url?scp=85077931317&partnerID=8YFLogxK
U2 - 10.1016/j.matdes.2020.108484
DO - 10.1016/j.matdes.2020.108484
M3 - Article
AN - SCOPUS:85077931317
SN - 0264-1275
VL - 188
JO - Materials and Design
JF - Materials and Design
M1 - 108484
ER -