TY - JOUR
T1 - Influence of the prior athermal martensite on the mechanical response of advanced bainitic steel
AU - Navarro-López, A.
AU - Hidalgo Garcia, Javier
AU - Sietsma, J.
AU - Santofimia Navarro, Maria
PY - 2018
Y1 - 2018
N2 - 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 (Ms). Specimens isothermally treated below Ms exhibit a good combination of mechanical properties, comparable with that of the specimens heat treated by conventional treatments above Ms, 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 Ms. The formation of prior athermal martensite and its tempering during the isothermal holding leads to the strengthening of the specimens isothermally heat treated below Ms at the expense of slightly decreasing their strain hardening capacity.
AB - 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 (Ms). Specimens isothermally treated below Ms exhibit a good combination of mechanical properties, comparable with that of the specimens heat treated by conventional treatments above Ms, 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 Ms. The formation of prior athermal martensite and its tempering during the isothermal holding leads to the strengthening of the specimens isothermally heat treated below Ms at the expense of slightly decreasing their strain hardening capacity.
KW - Bainitic ferrite
KW - Isothermal treatments
KW - Mechanical response
KW - Multiphase steels
KW - Prior athermal martensite
KW - Strengthening mechanisms
UR - http://resolver.tudelft.nl/uuid:cd79ea94-7654-401e-9504-d7db73093a9e
UR - http://www.scopus.com/inward/record.url?scp=85052226998&partnerID=8YFLogxK
U2 - 10.1016/j.msea.2018.08.047
DO - 10.1016/j.msea.2018.08.047
M3 - Article
AN - SCOPUS:85052226998
SN - 0921-5093
VL - 735
SP - 343
EP - 353
JO - Materials Science and Engineering A
JF - Materials Science and Engineering A
ER -