Metals - Montana State University Draft Forging Thinner web and rib, higher rib than conventional-type forgings. Up to rib thickness/height ratio 1/23. Without gy draft angle on rib

MetalsMetals

Class Objectives

• Recognize the different types of metals used in aircraft and where they are usedy

• Recognize that product form and heat treatment are directly related to material propertiesD l b i d di f h l i hi• Develop a basic understanding of the relationship between materials properties and design properties and values

Design and Analysis of Aircraft Structures 11-2

Wrought Products

Rolled• Sheet and plateSheet and plate• Shapes (BAC 1490

and so forth)• Bar, rod, wire

Extruded• Shapes and bar

Cast billet

p

Drawn• Tubing and wire

Forged• Block


• Die forgings

Cast Products

Risers

Cope

SprueDrag

CoreFlask

Gate Part

Drag

• Sand

• Permanent mold• Permanent mold

• Investment


• Die castings

Sheet and Plate

ST

LT

L

LT


Sheet and Plate (continued)

ThermalCast ingot Thermalhomogenization RollScalp billetCast ingot

Inspect, pack, ship

Precipitation

Stretcher stressrelieve

Solutionheat treat

Precipitationstrengthening

(aging)


heat treat

Extrusions

ST

ST

LArea with ST

properties STL

LTproperties

LT


Extrusions (continued)

Extruded shape

Ram

Die

Billet

Die

Billet

Ram

Die

Extruded shape

Direct ExtrusionProcess

Indirect ExtrusionProcess


Process Process

Forgings

Grain flow lines

L

LT

Plane of parting line

ST

Die Forging Cross Section


Forgings (continued)

ExtrudedExtruded billet

P f

Forging steps

Preform

Blocker

Finisher


Castings

Trimmed Casting (Aluminum Alloy C355)


Castings and Forgings are ViableAlternatives to Hogouts

• Forging

Casting• Casting

• HogoutHogout


Forging

Advantages

M t i l t d t i

Disadvantages

Ch t fi ti• Material stronger due to grain flow (longitudinal properties around bends and fillets), higher allowables because of

• Changes to configuration can be costly

• Fay surfaces and bores, higher allowables because of reduced cross section of starting stock

y ,threads, and more may require subsequent machining

• Machining time reduced (or eliminated for many precision forgings)

• Unit price less than hogout in many cases


Casting

Advantages

C l fi ti

Disadvantages

C t t i l ll bl t• Complex configurations are created once in the pattern or mold, and come free in the final product by the simple act

• Cast material allowables not as high as wrought material

• Changes to configuration can final product by the simple act of pouring molten metal

• Hollow features or internal

g gbe costly

passageways possible

• Almost always the least expensive methodexpensive method


Hogout

Advantages

P i i t l il bl

Disadvantages

Hi h t i l t i th• Precision tolerances available

• Minor configuration changes do not affect tooling

• High material waste in the form of chips

• Complex configurations with g

• Short cycle times possible, high-speed machine centers

d i dl ti

p gmany setups very costly, no hollow features

reduce spindle time

• Least costly for small order base partsp


Forging Process

Billet Preform Finisher


Billet Preform Finisher

Reduced Cross Section of Starting Stock

Hand ForgingsForm blocks, disks, cylinders,and rings by flat die.

No Draft ForgingThinner web and rib, higher rib thanconventional-type forgings. Up to ribthickness/height ratio 1/23. Withoutdraft angle on rib wall.g y g

Precisionforging

Conventionalforging

Hand forging

P/L of conventional-P/L of conventionaland blocker-typeforging

Blocked forging

P/L of no draft forging


Blocker- and conventional-type ForgingsPermit some amount of excess thickness and 3° to 10° draft angle to final shape of parts

P/L of no draft forging

Break-Even Point Represents Return on Investment

10,0009 000

Precision forgingbreak-even point

H t

9,0008,0007,000t,

$

Hogout6,0005,0004,000al

cos

t/par

t

Precision

4,0003,0002,0001 000

Tota

0 25 50 75 100 125 150 175 200

1,0000


Production quantities

Very Large Parts Require Forgings


Benefits

Cost savings

Weightreduction

Reduced parts

More rigidgstructure

Fewer components


pand easier to

assemble

Aluminum Alloys

C it 11%

Miscellaneous1%

Titanium 7%

Composite 11%

Steel 11%AluminumAluminum

70%

777 Model


777 Model

777 Aluminum Alloy Applications

Lower skin 2324and stringers 2224Lower spar chords 2224 and stringers 2224Lower spar chords 2224

Unpressurized skin 7075Frames stringers

Pressurized skin 2524

Upper skinsand stringers 7055

Frames, stringers7075 and 7150

Upper spar chords 7150

Keel beam chords 7150


pp p

Material Designation for Wrought Aluminum Alloys

70757075Major alloy element Assigned when the

alloy is registered

Modification of the original alloy


Material Designation for Wrought Aluminum Alloys (continued)

Unalloyed aluminum1 X X X

Alloy Family Major Alloying Element

Unalloyed aluminumCopperManganese

1 X X X2 X X X3 X X X

SiliconMagnesiumMagnesium and silicon

4 X X X5 X X X6 X X X Magnesium and silicon

Zinc6 X X X7 X X X


Material Designation for Cast Products

A356 0A356.0Modification alloy

designator

Ingot identifier

Alloy group Alloy registration


Material Designation for Cast Products—Major Groups

• 1XX.X, aluminum (99.00% pure)• 2XX.X, copper• 3XX.X, silicon, with additions of copper, magnesium• 4XX.X, silicon4XX.X, silicon• 5XX.X, magnesium• 6XX.X, unused series of numbers

7XX X inc• 7XX.X, zinc• 8XX.X, tin


Aluminum Alloy Temper Designations

7075 T67075-T6Material

designationTemper

designation


Aluminum Alloy Temper Designations

D i ti C diti

— O Annealed

Designation Condition

— W

— F

Solution treated and quenched(unstable)As fabricatedF

— H X X— T X X X X X

As fabricatedStrain hardenedHeat treated


Common TXX Tempers

• T3 Solution treat, cold work, natural aged• T4 Solution treat, naturally aged• T6 Solution treat, artificially aged (peak aged)• T73 Solution treat, artificially over-aged for

corrosion resistance • T81 Artificially aged after T3• T81 Artificially aged after T3


Stress-Relieved Tempers Reduce Distortion in Wrought Products

• Accomplished by stretching (after solution heat treatment)– For plate and rolled bar: TX51– For extrusions: TX510 or TX511

• Accomplished by compressive deformation (after SHT)– For forgings (hand, die, block): TX52

-T6 511-T6 511Standard heat-treat designation.

Material has been stress relievedafter quench and before aging.

Indicates minor straightening after stretching to meet straightness and flatness tolerances. This digit is 0 ifno straightening is allowed after stretching.

Material was stretched to accomplishstress relief. This digit is 2 whencompressive methods are used.


Ferrous Alloys

C it 11%

Miscellaneous1%

Titanium 7%

Composite 11%

Steel 12% Aluminum70%

777 Model


777 Model

Typical Ferrous Alloy Application

Midspar fitting aftMidspar fitting, aft engine mount

Inboard flap linkages

Main landing gearSlat tracks

g g

Nose landing gear


Classification of Ferrous Alloys

• Carbon steels• Alloy steelsAlloy steels• Ultra-high-strength steels• Stainless steels

– Austenitic– Ferritic– Martensitic– Precipitation-hardened


Material Designation for Carbon andAlloy Steel

43404340Primary alloying

elements (Ni, Cr, Mo)

Percent carbon in tenths (0.40)


Material Designation for Austenitic, Martensitic, or Ferritic Stainless Steels

304304Type—austenitic Assigned when

alloy is registered


Material Designation for Newer, High-Tech Alloys

9Ni 4Co 0 3C9Ni-4Co-0.3CNickel-cobalt alloy with approximately9% Ni, 4% Co, and 0.3% C


Material Designation for Some Precipitation-Hardening Stainless Steels

15 5PH15-5PHCr content (15%)

Precipitation hardening

Ni content (5%)


Usable Strength Ranges

AlloyStrength range (ksi)

125-145 150-170 160-180 180-200 200-220 220-240 275-300

4130 X X --- X --- --- ---4130 X X --- X --- --- ---

4140 X X --- X --- --- ---

4340 X X X X --- --- ---

4330M --- X --- X X X ---4330M --- X --- X X X ---

9Ni-4Co-0.20C --- --- --- X --- --- ---

9Ni-4cO-0.30C --- --- --- --- --- X ---

300M --- --- --- --- --- --- X300M --- --- --- --- --- --- X

4340M --- --- --- --- --- --- X

AerMet 100 --- --- --- --- --- --- X

15-5PH X X X X15-5PH X X X X --- --- ---

17-4PH X X X X --- --- ---

17-7PH --- X --- X --- --- ---

PH15 7Mo X


PH15-7Mo --- --- --- X --- --- ---

PH13-8Mo --- --- --- X X --- ---

Titanium Alloys

C it 11%

Miscellaneous1%

Titanium 6%

Composite 11%

Steel 11%Aluminum

70%

777 Model


777 Model

Typical Titanium Alloy Application

• Core cowl and thrustreverser hinge fittings

• Precooler hinge fittings

Inboard flap supportlinks (2 places)

Precooler hinge fittings• Forward upper link fitting

(GE engine only) Elevator actuatorfittings (3 places)

Windowsill and posts

APU firewall

pOutboard flap support links(4 places)

Hydraulic tubing

Main landing gear-actuatorsupport fitting (2 places)

tubing


• Forward landing-geartrunnion bearing housing

• Springs

Alpha Titanium Alloys

• Commercially pure titanium– 25 to 70 ksi (annealed condition)( )– Pneumatic ducts, door thresholds

• Ti-6Al-2Sn-4Zr-2Mo130 k i ( l d diti )– 130 ksi (annealed condition)

– Structure exposed to high temperature


Alpha-Beta Titanium Alloys

• Ti-3Al-2.5V

– 125 ksi (cold worked and stress relieved)

– Hydraulic tubing

• Ti-6Al-4V

– Structural fittings: 120 to 135 ksi (annealed condition)

– Fasteners: 160 ksi (solution-treated and aged-condition)


Beta Titanium Alloys

• Ti-10V-2Fe-3Al– 170 ksi (solution treated and aged condition)– Structural fittings up to 3 in thick

• Ti-15V-3Cr-3Al-3Sn– 150 ksi (solution-treated and - age condition)– Formed sheet, castings, pneumatic ducts

• Ti-3Al-8V-6Cr-4Mo-4Zr– More than 180 ksi (solution treated and - aged condition)( g )– Springs (tension and compression)


Critical Requirements forComponent Design

Wing

Lower Surface

• Skin (2xxx plate)• Stringer (2xxx extr)

• Damage tolerance, fatigue• Fatigue, damage tolerance, tension strength

U fUpper surface

• Skin (7xxx plate)• Stringer (7xxx extr)

• Compression strength, damage tolerance• Compression strength

Ribs

• Shear-tied (7xxx plate)• Intermediate (7xxx sheet)

• Shear strength• Stiffness shear strength• Intermediate (7xxx sheet) • Stiffness, shear, strength

Fuselage

Monocoque

• Skin (2xxx sheet)• Stringer (7xxx sheet)• Frames (7xxx sheet)

• Fatigue, damage tolerance, corrosion resistance• Fatigue, compression strength• Stiffness, fatigue, compression strength

• Floors

• Beams (extrusion, sheet)• Seat track

• Static strength, corrosion resistance• Static strength, corrosion resistance

Stabilizer

Lower Surface

• Skin (7xxx plate)• Stringer (2xxx extrusion)

• Static strength• Corrosion resistance, static strength

Upper Surface

• Skin (2xxx plate)• Stringer (2xxx extrusion)

• Tension strength, damage tolerance• Tension strength


Fin

• Skin (7xxx plate)• Stringer (7xxx extrusion

• Compression strength, damage tolerance• Compression strength

Critical Material Properties

Design Property Criteria Property Critical Material Property Property Evaluation

Static strength

Tension Fty, Ftu, FbruOHT, FHT, NT

Fty – small hole out OHT – open hole tensionFtu – large hole out FHT – filled hole tension

Structure must remain elastic to limit load and carry Ultimate Load. For composite materials, manufacturing flaws and Barely Visible Impact Damage (BVID) must be included

Fbru – Joint strength NT – notched tension

Compression Fcy, EcOHC, FHC, NC

Fcy – short columnsEc – long columnsOHC – open hole compressionFHC – filled hole compressionNC – notched compression

Shear Ftu Fty Fsu Ftu45 Fty45 thin webShear Ftu, Fty, FsuNC, NT

Ftu45, Fty45 – thin webFsu – thick webNT – notched tensionNC – notched compression

Durability

Fatigue Fatigue strength, open hole, notched specimen, low load &

Low load and high load transfer joint coupons data most reliable for material evaluation

Design service objective with high level of reliability

high load transfer joint coupons For composite, cycling to validate no growth.

Corrosion K1scc, SCC threshold and exfoliation rating

Heavy reliance on service experience

Damage Tolerance

Crack Growth Damage must be found before becoming critical. For composite

Fatigue crack growth characteristics

Inspection intervals & methodsg p

material, structure must demonstrate no detrimental growth with visible flaw.

CAI – compression after impact

Residual Strength Must carry limit load with large damage

Kapp, Fty, elongationH, - Composite fracture toughnessCAI

Kapp for low Toughness or wide panels, Fty for high toughness narrow partsHc for wide panels, CAI for local areas


Weight/Cost

Minimize within constraints Density, material costs Fabrication and maintenance costs must be accounted for

Weight Ratio for Structural Failure Modes

Failure ModeApproximate Weight Ratio

WoWc

Failure ModeApproximate Weight Ratio

WoWc

Tensile strength

Wc

PcPo

otyF

ctyF

E 50 F 50

Stiffness

Wc

PcPo

oE

cE

DFRCrippling strength

Buckling strength PcPo

oη

cη

PcPo

osE

csE.50 ocyF

ccyF.50

oE

cE

Fatigue performance

Crack growth PcPo

oM

cM

PcPo

DFRDFE

oc

Shear strength

Po cη

PcPo

ty 45° oF

ty 45° cF

cE

Residual strength

Po

PcPo

appK

appK

cM

PcPo

otyF

ctyF


Structural Material Usage on Commercial Aircraft (by weight)

100%17% 13% 12% 14%

11%70%80%90%

Miscellaneous

50%60%70% Miscellaneous

TitaniumComposites

82% 81% 78% 80%70%

20%30%40% Steel

Aluminum

0%10%20%


727 737 757 767 777

Selection of New Alloys on Airbus A380


Development of Material Uses in Airbusin Past 20 Years


New Al-alloys on A380 Wing


Notes

• Advanced metalic alloys were developed for B i 787Boeing 787

• GLARE, Aluminum Lithium , laser welded skin/stringer panels (6013), and FSW-Friction Stir s /st ge pa e s (60 3), a d S ct o StWeldeding are used on Airbus 380


Summary

• Develop or select the right alloy for the applicationS l t th i t d t f• Select the appropriate product form

• Select the proper temper or strength level• Consider materials properties and their relevance• Consider materials properties and their relevance

to performance criteria for a given application• Consider how the material and material properties

affect product performance and cost (recurring and non-recurring)

• New materials applications must be thoroughly• New materials applications must be thoroughly evaluated prior to design usage


Documents

Metals - Montana State University Draft Forging Thinner web and rib, higher rib than conventional-type forgings. Up to rib thickness/height ratio 1/23. Without gy draft angle on rib