m c t r c
Post on 06-Dec-2014
1.611 Views
Preview:
DESCRIPTION
TRANSCRIPT
MC-TRCMelt conditioned twin roll casting
MC-TRCMelt conditioned twin roll casting
Z BCAST (Brunel Centre for Advanced Solidification Technology)
Brunel University
UK
Introduction
Key challenges in the development of twin roll casting (TRC) include elimination of central line segregation, increasing cast speed, increasing the range of twin roll castable alloys.
MC-TRC=TRC+MCAST
Melt conditioned alloy melt contains well dispersed oxide particles which enhances heterogeneous nucleation
Enhanced nucleation allows fully equiaxed solidification
Fine and equiaxed grains reduces/eliminates central line segregation
All these will increase casting speed and enlarge the ranges of twin roll castable alloys.
MC-TRC ProcessMC-TRC Process
Melt Conditioned Twin Roll Casting Process
Microstructure of TRC Al-alloy strip
Microstructure of TRC Al-alloy strip
TL
TRC
5754 (0.4%Fe)
MicrostructureMicrostructure
TL
MC-TRC + GR
5754 (0.4%Fe)
MicrostructureMicrostructure
MC-TRC
AZ31 strip, 4mm thickness, as-cast
TRC
0.0 0.2 0.4 0.6 0.8 1.00
100
200
300
400
500
600
700 TRCMC-TRC
Gra
in s
ize
(mic
ron
)
Normalised thickness
AZ91D
0.0 0.2 0.4 0.6 0.8 1.00
100
200
300
400
500
600
700 TRCMC-TRC
Gra
in s
ize
(mic
ron
)
Normalised thickness
AZ91D
Microstructural variationMicrostructural variation
4mm AZ91D strip
Elemental distributionElemental distribution
0.0 0.2 0.4 0.6 0.8 1.05
10152025
01234
78849096
Normalized thickness
Al
Zn
Mg,
Al a
nd Z
n co
nten
t (w
t. %
) Mg
0.0 0.2 0.4 0.6 0.8 1.05
10152025
01234
78849096
Nomorlized thickness
Al
Zn
Mg,
Al a
nd Z
n co
nten
t (w
t. %
) Mg
TRC
4mm AZ91D strip
MC-TRC
Microstructural evolutionMicrostructural evolution
AZ31 stop sample
TRC
TRC
MC-TRC
Solidification mechanismsSolidification mechanisms
Tip Roll
L L+S S Nip
L
L+S
S
L
L+S
S
L
L+S
S
L
L+S
S
MC-TRCTRC
Mechanical propertiesMechanical properties
AZ91
(As-cast)
YS.
(MPa)
UTS
(MPa)
Elongation
(%)
TRC, tested at 3500C 11.0 47.0 43.4
MC-TRC, tested at 3500C 8.5 38.5 118.1
Mechanical propertiesMechanical properties
AZ31
(Rolled)
YS.
(MPa)
UTS
(MPa)
Elongation
(%)
TRC, Rolled at 4000C 181.6±4.3 243.1±6.1 9.6±1.6
MC-TRC, Rolled at 4000C 177.7±8.0 251.1±5.2 27.7±5.2
Advantages of MC-TRC over TRC
Increased melt fluidity, reduced sensitivity to processing conditions
Fine and uniform microstructure through the strip thickness
Eliminated/reduced central line segregation
Increased casting speed
Increased tolerance to impurity elements and inclusions
Enlarged twin roll castable alloy range
Increased deformability
Enhanced mechanical properties
Applicable to both Al-alloys and Mg-alloys
top related