The development of high strength hot rolled TRIP (Transformation induced plasticity)
-aided steel sheets
with 780 MPa was carried out by taking into account the addition of Nb and Mo to
0.2C–1.5Si–1.5
Mnmass% steel and coiling conditions after hot rolling. The results reveal that the
addition of 0.05% Nb can
attain higher elongation with higher strength compared with Nb-free steel. The
obtained tensile strength in
this steel was higher than 780 MPa. The multiple addition of 0.2% Mo with 0.05% Nb
results in higher TS
(Tensile Strength) by the large amount of fine NbMoC precipitates than Nb containing
steel without the deterioration
of TS–El (Elongation) balance under the possible hot rolling conditions. The good
ductility in
0.05% Nb containing steel was mainly obtained by large volume fraction and high
carbon concentration of
retained austenite. In addition, finely dispersed retained austenite made some
contribution to the improvement
of ductility.
