future materials for body structure applications

Uddeholm Automotive Seminar 2005-02-09

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Future materials for body structure applicationsFuture materials for body structure applications


Kaj Fredin, Advanced Body Engineering Volvo Car Corporation

Volvo Car Advanced Body EngineeringVolvo Car Advanced Body Engineering

YesterdayYesterday--TodayToday--Tomorrow Tomorrow Optimal Optimal material MIXmaterial MIX

Optimal Optimal material MIXmaterial MIX

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Process investments Cost Technology step Commonality

Comfort Safety Reliability Cost Environment Fuelconsumption Design Customer

satisfaction

Stiffness

Strength

Panel fit Weight Flexibility

Surfacefinish

Material

Structure

Joint

Complete vehicle Properties

Car Body Properties

Basic Body Technology Parameters

Durability

Colour

Corrosionprotection

Drivers & constraintsDrivers & constraints


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FactsFacts-- Trends & Wanted PositionTrends & Wanted Position

! !168gCo2/km ! 145gCo2/km !

2008 2012Mainly carbon steel, moderate level of continuous joints in conventional uni-body

produced in current process

Time850 S80 S60 XC90 S40+ S80+ XC90+

?

Necessary Technology

Shift

2000 2006 2009

Wanted Position2009

Total Passive Safety Performance

Projected body weight

Cost

The Steel Era

! !168gCo2/km ! 145gCo2/km !

2008 2012! !

168gCo2/km ! 145gCo2/km !

2008 2012Mainly carbon steel, moderate level of continuous joints in conventional uni-body


Mainly carbon steel, moderate level of continuous joints in conventional uni-body


Time850 S80 S60 XC90 S40+ S80+ XC90+

?


Shift


Shift

2000 2006 2009

Wanted Position2009



Cost



Cost

The Steel Era


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The average weight development corresponds to an annual increase of fuel consumption of 0,052l/100km (corresponding to approximately 1,2 gCO2/km). The weight increase results from increased requirements

in NVH, safety, convenience, driving & up-sizing

Body & trim weight contribution is currently 50-53% of the total car weight. The average weight of the car has

increased at a rate of 10kg per annum, platform to

platform

Weight developmentWeight development


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P1X54% HSS

23% >HSS

XC9057% HSS

21% >HSSS80

36% HSS2% >HSS

85036% HSS0% >HSS

74015% HSS0% >HSS

2400% HSS

0% >HSS

% HSS(Rm>340MPa)

% EHSS>(Rm>600MPa)

S80’59% HSS

25% >HSS

0

10

20

30

40

50

0

10

20

30

40

50

Approximate values

Steel sheet development within Volvo CarSteel sheet development within Volvo Car


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Tensile Strength, Rm (MPa)

Yield Strength, Re (MPa)

max 170-280 min 220 min 280 min 400

max 270-390 min 340 min 600 min 800MS HSS EHSS UHSS

RephosHSLA

DP

Rephos

HSLA

DP

HSS: HSLA & Rephos”Standard qualities” for high strength steel sheets. Rephos higher formability compared to HSLA.

HSS/EHSS: DP-steelsUsed for reinforcements and safety components for high load capacity and balanced weight impact, e.g. B-pillar reinf., roof bow, sill reinf.

UHSS: Boron-steels Similar applications as DP-steels and for extreme load cases, e.g. bumper beams, B.pillar reinf., roof bows.

Boron steel

Boron steel

High High StrengthStrength SteelSteel Sheets, EHSSSheets, EHSS within Volvo Car Stdwithin Volvo Car Std(Rpmin >220 Mpa, Rmmin >340 Mpa)


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Material Grade Distribution (%-weight)

HSS

EHSS UHSS

HSS

EHSS UHSS

XC90XC90XC90

46%

31%

20%3%

1%

47%

32%

13%7%

S40S40S40 S40 new Volvo patented front end, same concept as XC90. Frame of beams working in

compression and tension instead of bending.

Rephos

DP600 Boron

Volvo Car state of the art steel body structuresVolvo Car state of the art steel body structures

AlMS (Rp <180MPa)HSS (Rp = 180, <400MPa)

EHSS(Rp = 400, <800MPa) UHSS (Rp = 800MPa)

AlMS (Rm <340MPa)HSS (Rm 340, 380 < 420)

EHSS(Rm 600, <800MPa) UHSS (Rm 800MPa)

>

>>

>


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Not taking strain hardening into account = over dimensioning !Not taking strain hardening into account = over dimensioning !

virgin

2% strain5% strain

320

500

650

Plastic strainTr

ue s

tress

(MPa

)

DP600, Stress-Strain for different pre-strain levels

virgin

2% strain5% strain

320

500

650

Plastic strainTr

ue s

tress

(MPa

)

virgin

2% strain5% strain

320

500

650

Plastic strainTr

ue s

tress

(MPa

)


virgin

2% strain5% strain

320

500

650

Plastic strainTr

ue s

tress

(MPa

)


virgin

2% strain5% strain

320

500

650

Plastic strainTr

ue s

tress

(MPa

)

virgin

2% strain5% strain

320

500

650

Plastic strainTr

ue s

tress

(MPa

)


The ExtraThe Extra HighHigh StrengthStrength SteelSteel challengechallengeLesson learned, DP600 front side member application S40


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The suppliers different material concepts, process ability & scatter are concerns

Continue reducing weight with Advanced High Strength SteelsContinue reducing weight with Advanced High Strength SteelsReaching an additional 5% cost efficient weight reduction

DP600

Boron steel

MS-W1200:

DP600

Boron steel

MSW 1200

DP600

Boron steel

MS-W1200:

DP600

Boron steel

MSW 1200

MSW 1200: Martensitic hot rolled steelCP 800: Complex phase hot rolled steelTrip 700: Transformation Induced Plasticity cold rolled steelDP: Dual phase cold rolled steels

Toda

y

Tom

orro

w

>86,5Rmmin >800UHSS>1814Rmmin >600EHSS

Rmmin >380-420Rmmin >340HSS

(%)(%)(Mpa)

<3235


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And then ?And then ?Austenitic stainless steels

Combining high strength with excellent formability !!

Driver: Enabling weight reduction 1 step further than high strength steel. Lower mix-material risk compared to aluminium

Target: 40% weight reduction at lower cost/save kg than Aluminium.

Driver: Enabling weight reduction 1 step further than high strength steel. Lower mix-material risk compared to aluminium

Target: 40% weight reduction at lower cost/save kg than Aluminium.

B pillar section;

Sill

B pillar

Roof bow

Cant rail

B pillar section;

Sill

B pillar

Roof bow

Cant rail

Front section;

Bumper beam Crash box

Side member lower

Radiator beam

Spring-tower

Front section;Front section;


Side member lower

Radiator beam

Spring-tower


Side member lower

Radiator beam

Spring-tower


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Other light weight body structure materialsOther light weight body structure materialsInteresting or not ?

Fibre reinforced polymersi.e. Ip-structure, spare wheel well, parcel shelf

Sandwich materialsi.e. floor panels, roof, hood

Die cast magnesiumi.e. Ip-structure, SIPS-box

Aluminium (extrusion, castings & sheets)for various structural applications

Weight

P.Safety

Cost

Weight

P.Safety

Cost

Weight

P.Safety

Cost

Weight

P.Safety

Cost

Weight

P.Safety

Cost

Weight

P.Safety

Cost

Weight

P.Safety

Cost

Weight

P.Safety

Cost

Polymer Metal

JointsJoints

StructureStructure

MaterialsMaterials


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Magnesium

Multi phase steelsStainless steels

Continuous joints

Structural foams

Boron Steels

Aluminium

Fibre reinforced polymers

Multi material usage with high degree of continuous joints in upgraded structure

produced in a modified process

Multi material usage with high degree of continuous joints in upgraded structure

produced in a modified process

The future body structureThe future body structureImproving passive safety & reducing weight at minimum cost

Properties

In balance !

Weight

Cost

Properties

In balance !

Weight

Cost

future materials for body structure applications

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