TY - JOUR
T1 - Effect of austenite microstructure and cooling rate on transformation characteristics in a low carbon Nb-V microalloyed steel
AU - Olasolo, M.
AU - Uranga, P.
AU - Rodriguez-Ibabe, J. M.
AU - López, B.
PY - 2011/3/15
Y1 - 2011/3/15
N2 - Deformation dilatometry has been used to simulate controlled hot rolling followed by cooling of a Nb-V low carbon steel, looking for conditions corresponding to wide austenite grain size distributions prior to transformation. Recrystallization and non-recrystallization deformation schedules were applied, followed by controlled cooling at rates from 0.1 °C/s to about 200 °C/s, and the corresponding continuous cooling transformation (CCT) diagrams were constructed. The resultant microstructures ranged from polygonal ferrite (PF) and pearlite (P) at slow cooling rates to bainitic ferrite (BF) accompanied by martensite (M) for fast cooling rates. Plastic deformation of the parent austenite accelerated both ferrite and bainite transformations, displacing the CCT curve to higher temperatures and shorter times. However, it was found that the accelerating effect of strain on bainite transformation weakened as the cooling rate diminished and the polygonal ferrite formation was enhanced. Moreover, it was found that plastic deformation had different effects on the refinement of the microstructure, depending on the cooling rate. An analysis of the microstructural heterogeneities that can impair toughness behavior has been done.
AB - Deformation dilatometry has been used to simulate controlled hot rolling followed by cooling of a Nb-V low carbon steel, looking for conditions corresponding to wide austenite grain size distributions prior to transformation. Recrystallization and non-recrystallization deformation schedules were applied, followed by controlled cooling at rates from 0.1 °C/s to about 200 °C/s, and the corresponding continuous cooling transformation (CCT) diagrams were constructed. The resultant microstructures ranged from polygonal ferrite (PF) and pearlite (P) at slow cooling rates to bainitic ferrite (BF) accompanied by martensite (M) for fast cooling rates. Plastic deformation of the parent austenite accelerated both ferrite and bainite transformations, displacing the CCT curve to higher temperatures and shorter times. However, it was found that the accelerating effect of strain on bainite transformation weakened as the cooling rate diminished and the polygonal ferrite formation was enhanced. Moreover, it was found that plastic deformation had different effects on the refinement of the microstructure, depending on the cooling rate. An analysis of the microstructural heterogeneities that can impair toughness behavior has been done.
KW - EBSD
KW - ferrite unit
KW - microstructure refinement
KW - misorientation angle
KW - recrystallized/unrecrystallized austenite
KW - transformation
UR - http://www.scopus.com/inward/record.url?scp=79151480960&partnerID=8YFLogxK
U2 - 10.1016/j.msea.2010.11.078
DO - 10.1016/j.msea.2010.11.078
M3 - Article
AN - SCOPUS:79151480960
SN - 0921-5093
VL - 528
SP - 2559
EP - 2569
JO - Materials Science and Engineering: A
JF - Materials Science and Engineering: A
IS - 6
ER -