Alcoa Aluminum: Rolled Productsalcoainnovation.ca/fr/pdf/Alcoa_Aluminum_GRP_webinar_03_18_15.pdf ·...
Transcript of Alcoa Aluminum: Rolled Productsalcoainnovation.ca/fr/pdf/Alcoa_Aluminum_GRP_webinar_03_18_15.pdf ·...
Alcoa Aluminum: Rolled Products
Dr. J. Daniel Bryant
Technical Fellow, Alcoa Technical Center (Pittsburgh, Pennsylvania)
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March 18, 2015
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Alcoa covers every stage of aluminum production
and is a leader in major end markets O
pera
tio
ns
Upstream (41%) Bauxite mining
Alumina refining
Aluminum smelting
Aluminum recycling
Downstream (26%) Fastening Systems
Super-alloy castings
Wheel & Transportation
Building & Construction
Forgings & Extrusions
Midstream (33%) Aluminum Sheet & Plate
Aluminum Can Stock
Primary
Aluminum
Automotive
Transportation
Packaging
Building/
Construction
Aerospace
Industrial
Oil & Gas
Consumer
Electronics
$7.5bn $6.1bn $4.8bn
Alcoa Global Packaging (AGP)
Aero, Transportation & Industrial (ATI)
China & Consumer Electronics (CRP)
Global Rolled Products
– a global business spread across 5 continents
North
America
Europe Russia
Middle
East
Australia
Latin
America
Market-facing Global Business Units… …with a Global footprint
China
Product Lines:
• Can (Beverage & Food)
• Specialty Foil
• Industrial
Product Lines:
• Commercial Aerospace
• Auto Body & Brazing
• Industrial
• Commercial Transportation
Product Lines:
• Can (Beverage)
• Brazing
• Commercial Transportation
• Consumer Electronics
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GRP business unit structure and operating locations
Research Directions at Alcoa Technical Center in Sheet and Plate Products:
1. Improve Process Efficiency:
• improve conversion (secondary processing) efficiency
• reduce scrap (improve recovery –planned and unplanned)
• improve output (ROC)
• reduce labor content per kg
2. Improve Sustainability
• reduce effluent (solids, volatiles, etc.)
• reduction in greenhouse gas generation
• improve recycling
3. Introduce Improved Products
• superior process performance (for our processes)
• superior process performance (for our customers’ processes)
• superior service performance (for their customers)
4
Alcoa Technical Center:
Our Role in Global Rolled Products
The fundamentals: What is rolling?
….a process in which
a material is passed
between two parallel
rotating rolls, causing
the material to be
reduced in thickness
and increased in length
If there is no lateral spreading of the sheet, i.e. ew = 0,
(usually when w >>t) then et = -el and we call this plane strain
If there is any spread in the width direction
(ew 0) it is no longer plane strain
Sheet and Plate Manufacturing
Example: Davenport Works - 65 Years Serving Our Customers
• Began production in 1948
• $716M in Total Assets
• 132 acres under roof
• 2,300 employees
• 110 alloys, 8,000 specs
• 1,100 global customer locations
Operations:
• Metal Purification
• Casting
• Rolling, Stretching
• Sawing/Machining
• Heat Treatable & Non-Heat Treatable
• Sheet & Plate
Diversified Product Base:
• Aerospace and Defense
Sheet & Plate
• Automotive Sheet
• Industrial Sheet & Plate
• Commercial Transportation
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Sheet and Plate Manufacturing at Davenport Works
• Ships 500 million lbs/yr. or 1.3 M lbs. a day of finished product
• Produces plate products up to 220” wide and 110 feet long
• Three reversing hot mills, 220” wide, 160” wide, 144” wide
• 100” 5 stand hot mill
• Two 100” cold mills
• 86” wide continuous heat treat line
• New 88” wider continuous heat treat line (exclusively for automotive)
• Two vertical heat treat lines
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Sheet and Plate Manufacturing
Theme:
Understanding the metallurgical thinking and microstructural changes as we
follow aluminum through the processing flowpath....
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Sheet and Plate Manufacturing: Ingot
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Multiple ingots are cast at a
single composition using
direct chill (DC) casting
To remove “liquated” layer and provide a flat surface
for rolling, ingots are scalped prior to homogenization
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250 microns
Solidifies as dendritic grains
(also known as: cells/crystals)
Constituent
Particles
Non-uniform tinting
within grains is due to
the non-uniform distribution
of elements such as Mg, Mn, etc.
Tracking the Metallurgical Evolution: As-Cast Microstructure
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Tracking the Metallurgical Evolution: As-Cast Microstructure
50mm
Si - much of it combines with Mg
to form Mg2Si particles.
(these appear dark as-polished)
Fe - very low solubility in solid Al
It tends to form Al3Fe and Al12Fe3Si2
type particles in the last stages
of solidification – these are constituents
Aluminum Matrix -
has Mg, Mn*, Cu, etc.
dissolved within it -
usually not uniformly
distributed
* Mn, like Fe, is also has low
solubility in solid Al - but is
unable to partition into
liquid during solidification
and gets trapped in solid.
Will come out during ingot
homogenization as dispersoids
Constituent Particles
5182 Can End Stock
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Mn, although highly
insoluble in Al
was trapped in solid
during solidification
During the long thermal
exposure during
ingot homogenization, Mn
is able to diffuse and
form discrete dispersoids
of Al6(Mn,Fe)
...and perhaps also some
Al12(Mn,Fe)3Si2
Tracking the Metallurgical Evolution: After Homogenization
3104 Can Stock
4-high
work rolls
backup roll
backup roll
2-high
reversing
2-high
5-stand tandem mill
slab
Load = Pressure x Area
Load = Pressure x (WxL)
So, Load a L
… and a smaller work roll diameter
therefore results in lower loads
What is the advantage of a
smaller work roll diameter?
L1 L2
Sheet and Plate Manufacturing: Hot Rolling
Sheet and Plate Manufacturing: Hot Rolling
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Ingots are rolled down to progressively
thinner gauges in reversing mills.
Deforming becomes more plane strain
(the sheet maintains its width and gets
progressively longer) as rolling proceeds.
Rolled plate seen on the run-out table to
the right...
5-Stand Hot Continuous Mill used for rolling to sheet thicknesses (“hot band”)
Sheet and Plate Manufacturing: Hot Rolling
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Coil After Exit from Hot Continuous Mill
Sheet and Plate Manufacturing: After Continuous Hot Rolling
Hot rolled coils, with gauges in
the 2mm to 8 mm range, are
now either given an anneal
treatment or are passed
directly to cold rolling to
reduce the gauge and modify
the crystallographic texture
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Unannealed hot rolled microstructure
Hot rolled products can be
come off the mill fully
recrystallized, partially
recrystallized or
unrecrystallized, depending
on the alloy, the reduction
schedules and the rolling
temperature.
When recrystallization occurs
the elongated, strained hot
rolled grains are replaced by
a new set of low aspect ratio,
strain-free grains
Hot rolled product, therefore,
can be either self-annealed
or unannealed
A batch anneal (also called
an hot line anneal or
intermediate anneal) can be
imposed to complete
recrystallization, if so
desired...
Tracking the Metallurgical Evolution: Annealing after Hot Rolling
Partially annealed hot rolled microstructure
Fully annealed hot rolled microstructure Partially annealed hot rolled microstructure
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Tracking the Metallurgical Evolution: Cold Rolling and Annealing
Path 1 Path 2 Path 3 Path 4
Cold Roll 50% Cold Roll 33% Anneal Cold
Roll
60%+
Anneal Anneal
Cold Roll 20% Cold Roll 40% Cold Roll 60%
Anneal
33 mm 18 mm 13 mm 10 mm
As-Hot Rolled 5xxx...
Yield Strength
88 MPa
Yield Strength
101 MPa
Yield Strength
91 MPa
Yield Strength
105 MPa
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Crystallographic Texture: Controlling Anisotropy
After exiting the hot continuous mill, the
strip recrystallizes….
new grains
nucleate among
hot deformed
grains
grains grow grains impinge fully recrystallized
Some/many of the
recrystallized grains
are of the cube
orientation….
When the cube faces of face
centered cubic crystal structure
of Al is lays in the sheet plane
& FCC edges are parallel to
rolling direction, we have
cube texture
RD
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The cube texture from hot rolling imparts ‘0-90o’ earing
tendencies to the recrystallized strip….
0 90 180 270 360
0-90o earing of cube texture
100% cube texture
50% cube + 50% random
100% random
Heig
ht of C
up (
arb
itra
ry u
nits)
angle from rolling direction, degrees
Crystallographic Texture and Earing
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The cold rolling texture causes ears to be
formed at all locations ~45o from RD
(actually closer to 48o)….
0 45 90 135 180 225 270 315 360
45o earing of rolling texture
Heig
ht of C
up (
arb
itra
ry u
nits)
angle from rolling direction, degrees
Crystallographic Texture and Earing
Rolli
ng D
irection
Rolli
ng D
irection
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So, the secret to low earing is to product the right amount of cube texture in the hot
rolling process to balance with the texture subsequently introduced in cold rolling to
final gauge….
0-90o earing of cube texture
Heig
ht of C
up (
arb
itra
ry u
nits)
0 45 90 135 180 225 270 315 360
well balanced earing
Heig
ht of C
up (
arb
itra
ry u
nits)
angle from rolling direction, degrees
So while zero earing is only possible with random textures, earing can be
reduced by balancing crystallographic textures introduced in different steps in
the rolling process...
0 45 90 135 180 225 270 315 360
45o earing of rolling texture
Heig
ht
of
Cup
(arb
itra
ry u
nits)
angle f rom rolling direction, degrees
+ =
Crystallographic Texture and Earing
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Real World Example:
Aluminum Can Stock
AA3104
0 45 90 135 180 225 270 315 360
Heig
ht of C
up (
arb
itra
ry u
nits)
angle from rolling direction, degrees
Crystallographic Texture and Earing
0 45 90 135 180 225 270 315 360H
eig
ht of C
up (
arb
itra
ry u
nits)
angle from rolling direction, degrees
Real World Example:
Aluminum End Stock
AA5182
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Crystallographic Texture
Control is Important for
Manufacturability:
Forming
Hemming
Isotropy in Properties
But it is also Important for
Service Performance:
Surface Appearance
Aluminum Automotive Bodysheet
Alcoa Automotive Engineering
2002B
Inner sheet aluminum release after Analyses
Crystallographic Texture In Automotive Sheet
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Crystallographic Texture: Automotive Bodysheet
Surface appearance in
aluminum autobody sheet
can be compromised by
bands of cube oriented
grains that are remnants
from the hot rolling
process. These “ridging” or
“roping” lines are a cause
for rejection....
27 August 2007
1 in 3 trucks in North
America ride on Alcoa
Wheels
Examples of Alcoa Products Used on Commercial Vehicles
Typical Steel truck wheel weighs 35 kg
versus typical aluminum truck wheel
weighs 21 kg (roughly 40% savings)
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Trailers
• 95% of gasoline tankers are aluminum in the US
• Powered Bulk haul trailers with pressurized
material movement are normally aluminum in the US
• Dump truck boxes in aluminum are common
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Use Alloy Key Attributes
Chassis, Trailer Frames 6061-T6 extrusion Strength, fatigue*
Side Sheets 3004, 5052-H291 Painted, durability
Roof 3003-H1x Wide width
Fuel Tanks 5052-O Impact resistance*
Compressed Air 5083, 5754, 5154 Impact resistance*
Wheels 6061-T6 Fatigue, surface, wear
Cab Sheets 6022, 6111-T4, 5182-O Formability
Bumpers 6061, 5xxx Surface, strength
Trim Various 3xxx, 5xxx Good surface
Application of Aluminum in Commercial Transportation
Aluminum Alloys for Aerospace
Alcoa “invented “ aluminum alloy development...
First recorded alloy 1100 (2S) developed in 1888
3003 (3S) followed in 1906
First important heat treated alloy was 2017 (1916), followed by 2025
(1921), and 2014 (1928)
2024 appeared in 1932 and is still a workhorse alloy for aerospace
First important high strength alloy was 7075 (1942)
large majority of commercially important aerospace alloys developed by
Alcoa
…and we have been innovating ever since
Important aerospace alloys developed by Alcoa:
2014, 2017, 2024, 2124, 2219, 2519, 2524, 2026, 2624, 2090,
2099, 2060, 2055
6061, 6013
7075, 7175, 7475, 7178, 7050, 7150, 7055, 7085, 7255
Important tempers developed by Alcoa
T73, T76, T74, T77
Aluminum Alloys for Aerospace
1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Spar &
Thick
Product
Upper Wing
Fuselage
Lower
Wing
Military &
Space
Unialloy
7050-T7451 7085-T7651
A380
2017-T4 2024-T3
DC3
2090-T83
2097
2195-T8M4
Space Shuttle
2324-T39
757/767
2624-T39
2026-T3511
7075-T651
B29
7178-T651
707
7075-T7351
7075-T7651
L1011
7150-T651
757/767
7150-T6151
A310/MD11
7055-T7751
777
7150-T7751 7255-T7951
A380
2524-T3
777
6013-T651
A380
2005
2099-T83 A380
7085-T7652
2060-T8E30
C919
7055-
T76511
7085-T7451
2624-T351
A340-500/600
Alcoa Aluminum Aerospace Alloy Development History
2020-T651
A5
2099-T86
787
7085-T7452
F-35
7085-T7452
787
7475-T7351
2010
2040-T6
F-35
2099-T81 A380
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The product of aging of Al-
Cu-Li Alloys: strengthening
precipitates...
Precipitation Strengthening: High Strength Aerospace Alloys
3rd Generation Al-Li alloys have been developed by optimizing alloy
composition, TMP and tempering for a good balance of:
Density
Strength and toughness balance
Low anisotropy of mechanical properties
Fatigue crack growth resistance
Corrosion resistance
Thermal stability
Manufacturability
Attractive applications are being identified for lower wing, upper wing,
fuselage, thick sections of civil transport in addition to military and space
applications
3rd Generation Al-Li Alloys
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1. Manufacture of Rolled Aluminum Products is a Multi-Step Operation
• Ingot Casting
• Homogenization
• Scalping
• Hot Rolling
• Intermediate Annealing
• Cold Rolling
• Heat Treatment (coil annealing, continuous heat treatment, aging)
2. Thermo-Mechanical Processing is used to Control Product Gauge, Properties and
Anisotropy
• Strength
• Toughness
• Corrosion Resistance
• Surface Appearance
• Crystallographic Texture
3. The Microstructural Evolution through the Process Guides Metallurgical Decisions
Summary