STEEL + TECHNOLOGY 01/2020 EXTRACT

STEEL TECHNOLOGY | 41
Table 2. Semiquantitative chemical analyses via EDX (wt.-% rounded))
0 1 2 3
MgO 10% 11% 4% --
Al 2 O 3 13% 14% 16% --
SiO 2 -- -- 66% --
TiO 2 1% 2% 1% --
Cr 2 O 3 44% 59% 10% --
Fe x O y 32% 14% 3% --
Remark
Chromite from
the ladle well
filler
Boundary of
chromite grain
with reduced
Fe x O y content
Siliceous
phase containing
oxides
from the ladle
well filler
Table 3. Semiquantitative chemical analyses via EDX (wt.-% rounded)
Steel 1 after
crucible test
96 wt.-% Fe,
4 wt.-% Cr
Figure 8. Crucible test 2 with conventional
ladle well filler and Steel 2 (Picture:
Purmetall)
0 1 2
MgO -- 9% --
Al 2 O 3 >99% 67% --
SiO 2 -- -- --
TiO 2 -- -- --
Cr 2 O 3 -- 3% --
MnO -- 21% --
Fe x O y -- -- --
Remark Alumina crucible MnO-rich phase
including oxides
from the ladle well
filler (Mg,Mn)O
(Al,Cr) 2 O 3
Steel 2 after crucible
test
85 At.-% Fe, 10
At.-% Cr, 3 At.-%
Mn, 1 At.-% Si
Table 4. Semiquantitative chemical analyses via EDX (wt.-% rounded)
0 1 2
MgO -- 3% --
Al 2 O 3 -- 37% --
SiO 2 -- 57% --
TiO 2 -- -- --
Cr 2 O 3 -- -- --
MnO -- -- --
Fe x O y -- -- --
Remark
Steel 2 after crucible
test
78.8 At.-% Fe,
16.5 At.-% Mn,
2.5 At.-% Si,
2.3 At.-% Al
ventional ladle well filler and steel 1 of crucible-test
1.
Conventional ladle well filler consists in its
initial state of chrome ore and silica sand.
Siliceaous phase
3 wt.-%
Na 2 O
Manganese steel
78.8 wt.-% Fe,
16.5 wt.-% Mn,
2.5 wt.-% Si,
2.3 wt.-% Al
After the thermal treatment at 1,600°C the
conventional ladle well filler forms a dense
texture of dense chrome ore particles (light
grey) and a secondary phase which is of low
Figure 9. Crucible test 3 - new type of
ladle well filler and Steel 2 (Picture:
Purmetall)
viscosity at 1,600°C (dark grey). The outer rim
of the chrome ore particles are reduced in
their Fe x O y amount. The secondary formed
phase consists of SiO 2 from the silica sand
and the oxides of the chrome ore. This means
a diffusion of the oxides MgO, Al 2 O 3 , Cr 2 O 3
and Fe x O y from the chrome ore to the siliceous
secondary phase took place.
Additionally, redox reactions between the
conventional ladle well filler and the ball bearing
steel take place. Small amounts of manganese
and silicon from the steel diffuse into
the ladle well filler and get oxidized (MnO- and
SiO 2 -pickup into the ladle well filler). On the
other hand, Cr 2 O 3 of the ladle well filler diffuses
into the steel and is reduced to metallic
chrome (Cr-pickup into the steel).
In comparison figure 11 shows a SEM
picture of the texture formed at the contact
area of conventional ladle well filler
STEEL + TECHNOLOGY 2 (2020) No. 1