1. This study examines the possibility of manufacturing thin sheets of steel in an environmental friendly manner and properties that are
superior to conventionally manufactured ones.
APT revealed the presence of nano-scale Vanadium rich clusters that were
not observable using TEM. Concurrent precipitation of these clusters in
vanadium alloyed strip cast steels are responsible for the retarded
recrystallization and fine grains.
20 nm
Deakin University CRICOS Provider Code: 00113B
INTRODUCTION
Out of 1.4 billion tonnes of steel manufactured every year, almost 50% are thin flat products. Conventional manufacturing methods demand
nearly 1.8x109 Joules of energy to produce one ton of thin strip steel. Alternatively, to eliminate the energy intensive processes, a new and
emerging technology is manufacturing steel sheets directly from molten metal by Direct strip casting (DSC). DSC process not only simplifies
the production route but also reduces the energy consumption by 90%, thereby reducing the harmful impact on environment. However,
rapid conversion of liquid steel into thin steel strips generally results in microstructures and mechanical properties that are different to
conventionally manufactured ones. Despite the significant benefits, current limited knowledge about the microstructural development
during strip casting and secondary processing is hindering the advancement of DSC process. This project aims to investigate the influence of
solute elements, mainly carbon and vanadium, in the microstructural development during strip casting and rolling-annealing process. A
multi-scale approach, from microscopic to atomic scale, is utilized to elucidate the solute behaviour in strip cast steels.
C-0.09,N-0.01 wt% and V-0.04 wt%
EBSD analysis showed that DSC produces a highly complex
microstructure with an average grain size of 55 µm.
0
0.2
0.4
0.6
0.8
1
1.E+1 1.E+3 1.E+5
FractionRecrsytallized
Time (s)
Recrystallization studies showed a significant difference in
kinetics as well as the grain size evolution due to Vanadium
addition.
0
10
20
30
40
50
60
70
Grainsize(µm)
0wt% V
0.04wt% V
0.04 wt% V
Strip-Cast
Recrystallized
0
2
4
6
8
10
12
14
16
-1 0 1 2 3
Concentration(at%)
Distance (nm)
C %
N %
P %
S %
Cu %
V %
ATOM PROBE TOMOGRAPHY
Effect of clusters in Direct Strip Cast steels
MAHENDRA RAMAJAYAM, A.Prof. NICOLE STANFORD & Prof. PETER HODGSON
Institute of Frontier Materials, Geelong Technology Precinct.
SIGNIFICANCE
RECRYSTALLIZATION
50% Cold Rolling + 650°C annealing
DSC MICROSTRUCTURE
Matrix Cluster