TY - JOUR
T1 - Controlling the work hardening of martensite to increase the strength/ductility balance in quenched and partitioned steels
AU - Findley, K.O.
AU - Hidalgo Garcia, J.
AU - Huizenga, R. M.
AU - Santofimia Navarro, Maria
PY - 2017
Y1 - 2017
N2 - The role of retained austenite on tensile behavior in quenched and partitioned (Q&P) steels has been studied extensively, but the deformation behavior of martensite, which comprises the majority of Q&P microstructures, has received less attention. In this investigation, martensite properties were varied through heat treatment in a low carbon Q&P steel consisting of retained austenite and martensite. Additional conditions were produced by reheating the Q&P steel to 450 °C for 30 min or to 700 °C followed immediately by quenching. The reheated microstructures contained similar fractions of retained austenite as the non-reheated Q&P microstructures, but reheating tempered the martensite, thereby decreasing martensite dislocation density. The reheated conditions had a lower yield stress and initial work hardening rate than the non-reheated Q&P condition. However, the reheated conditions had a greater work hardening rate at larger strains and greater uniform strain due to less stable retained austenite. Furthermore, the tensile strength of the condition reheated to 450 °C was nearly equal to the non-reheated condition. In addition to retained austenite to martensite transformation, the early stage work hardening rate of martensite is critical to ductility and is dependent on martensite dislocation density, which can be decreased through tempering.
AB - The role of retained austenite on tensile behavior in quenched and partitioned (Q&P) steels has been studied extensively, but the deformation behavior of martensite, which comprises the majority of Q&P microstructures, has received less attention. In this investigation, martensite properties were varied through heat treatment in a low carbon Q&P steel consisting of retained austenite and martensite. Additional conditions were produced by reheating the Q&P steel to 450 °C for 30 min or to 700 °C followed immediately by quenching. The reheated microstructures contained similar fractions of retained austenite as the non-reheated Q&P microstructures, but reheating tempered the martensite, thereby decreasing martensite dislocation density. The reheated conditions had a lower yield stress and initial work hardening rate than the non-reheated Q&P condition. However, the reheated conditions had a greater work hardening rate at larger strains and greater uniform strain due to less stable retained austenite. Furthermore, the tensile strength of the condition reheated to 450 °C was nearly equal to the non-reheated condition. In addition to retained austenite to martensite transformation, the early stage work hardening rate of martensite is critical to ductility and is dependent on martensite dislocation density, which can be decreased through tempering.
KW - Mechanical behavior
KW - Quenching and partitioning
KW - Retained austenite
KW - Tempered martensite
UR - http://resolver.tudelft.nl/uuid:53208386-4179-428b-8986-7b4e02cae0cc
UR - http://www.scopus.com/inward/record.url?scp=85008385091&partnerID=8YFLogxK
U2 - 10.1016/j.matdes.2016.12.065
DO - 10.1016/j.matdes.2016.12.065
M3 - Article
AN - SCOPUS:85008385091
SN - 0264-1275
VL - 117
SP - 248
EP - 256
JO - Materials & Design
JF - Materials & Design
ER -