Mr. Yoshio Itsumi Senior Researcher, Titanium Research & Development Section

Kobe Steel, Ltd.

“A Newly Developed Press-Formable High-Strength Titanium Alloy.” The quantity of cp titanium sheet products shipment has been increasing over the last 10 years. Now a day, plate type heat exchanger (PHE) has become major application. At present, though the highest press-formability of cp titanium (that is the softest: ASTM Gr.1) is required in manufacturing “plates“ parts, PHE users request higher working pressure for higher performance in some cases. In other words, titanium sheet itself must have higher strength without deterioration of press-formability. In this paper, in order to satisfy this demand, we have proposed a newly Ti-1.5Fe alpha-beta alloy, which has superior combination of high tensile strength over 500MPa and excellent press-formability, comparing ASTM Gr.2 sheet. These characteristics have been achieved by adding appropriate Iron content to obtain higher strength and maintaining alpha-beta dual phase microstructure, consequently refining microstructure and suppressing Oxygen content in order to maintain higher ductility / press-formability.

A newly developed press-formable high-strength

titanium alloytitanium alloy

September 23th 2008September 23th 2008

YOSHIO ITSUMIKAKOGAWA WORKS, R&D Center

Titanium R&D sectionKOBE STEEL LTD

1

KOBE STEEL, LTD.

ContentsContents

PHE and Titanium market for PHE

R i t t tit i f PHERequirements to titanium for PHE

Characteristics of a newly developed alloy

Simulation technique for press-forming

C l iConclusion

2

What is PHE?What is PHE? PHE = Plate Heat Exchanger

A l fAn example of corrugated pattern

3

Working principle of PHE PHE productCourtesy of Alfa Laval

Applications of PHE using titanium plates pp g p<Conventional application>

Engine cooler for shipsCentral cooling system Power / Chemical / Desalination etcPower / Chemical / Desalination,etc

<Near future application>Thermal Energy Conversion Plant

Deep Ocean WaterSurface Water(warm)

gy-DTEC

Discharged ThermalEnergy Conversion

4

Deep Ocean Water(cold)-OTEC

Ocean Thermal Energy Conversion Concept of OTECFrom Institute of Ocean Energy,

Saga University

Titanium shipment for PHE

10 000

ta u s p e t o

Forecast for construction of DTEC/OTEC* plant

8,000

10,000

MT)

For PlantsFor Ships

4 000

6,000

men

t (M

2013 2018Power generation

output (MW) 100 1000

2,000

4,000

Shi

pm output (MW)Quantity of

titanium plate (MT) 1,800 18,000

02006 2007 2008 2009 2010

Year

5

Year

Requirements to titanium for PHEq

PHE d S l tiPHE needs

-Low cost & Stable mass supply

Solution

-New extracting/refining methods >Permissible impuritiesStable mass supply

-Higher performance

>Permissible impurities

-Higher strength with-Higher performance>Higher pressure>Higher temperature>Higher heat transfer rate

-Higher strength withgood press-formability

-Simulation technique for plateHigher heat transfer rate Simulation technique for plate forming considering formingproperties of the material

6

Requirements to titanium for PHEq

PHE d S l tiPHE needs

-Low cost & Stable mass supply

Solution

-New extracting/refining methods >Permissible impuritiesStable mass supply

-Higher performance

>Permissible impurities

-Higher strength with-Higher performance>Higher pressure>Higher temperature>Higher heat transfer rate

-Higher strength withgood press-formability

-Simulation technique for plateHigher heat transfer rate Simulation technique for plate forming considering formingproperties of the material

7

A new refining method in Japang p”JTS method” under development

Cl2ChlorinationTiO + C + 2Cl →　TiCl + CO 22 2 4TiO + C + 2Cl →　TiCl + CO 22 2 4

－ ＋Diaphragm

Ca/CaCl2

CaCl2TiCl

Raw Material

Ca ReductionTiCl4

PlasmaRecovering Electrolysis

TiCl + 2Ca → Ti + 2CaCl 4 2TiCl + 2Ca → Ti + 2CaCl 4 2

Reactor

TiSeparation

Melting

8

by Osaka Titanium Technologies & Toho TitaniumCaCl2

Requirements to titanium for PHEq

PHE d S l tiPHE needs

-Low cost & Stable mass supply

Solution

-New extracting/refining methods >Permissible impuritiesStable mass supply

-Higher performance

>Permissible impurities

-Higher strength with-Higher performance>Higher pressure>Higher temperature>Higher heat transfer rate

-Higher strength withgood press-formability

-Simulation technique for plateHigher heat transfer rate Simulation technique for plate forming considering formingproperties of the material

9

High pressure operation in DTECWarmLiquid Liquid

WarmLiquid (ex. NH3(G)+H2O(L))

Liquid + GasHigh pressure operation in DTEC

LiquidHigh

Pressure

Cooling Cooling

Heating Heating

Ti Plate

Cool Liquid

LiquidTi PlateCool

LiquidLiquid

10

Conventional PHE DTEC/OTEC PHE2.5MPa(Ex.) 15MPa

Alloy Design of Ti-1.5FeAlloy Design of Ti 1.5Fe<Elements>F 1 0 2 5 t% S l ti h d i-Fe:1.0-2.5 wt% Solution hardening

and β phase

<Process>-Rapid heating anneal fine and uniformusing APL* grains Ti-1.5Fe 20mmusing APL grains *Annealing Pickling Line

11

Good balance of strength and formability Unalloyed Ti (Gr.1)

Stretch formability and strength

12m

y gof Ti-1.5Fe

JIS class10

11al

ue /m

m

JIS class 1JIS classGr.1 Ti Fe systemJIS class

JIS class8

9

n te

st

va JIS class 1

JIS class 2

JIS class

JIS class

9Gr.1

Gr 2

Ti-Fe system

JIS class

6

7

Eric

hsen JIS class -2JIS class

6

Gr.2

Thickness：0 3mm

5200 300 400 500 600 700

Tensile Strength / MPa

E

12

Thickness：0.3mm

Good balance of strength and stretch-type formability

g

An evaluation method of formability for PHE

Herringbone type test die

An evaluation method of formability for PHE Pressed sample

Scoring at each2 : No crack

Die Size 100mm X 100mm

Scoring at each circled point

2 : No crack1 : Necking0 : Crack

13

Formability(%)= X 100 Full Marks(No crack)Summed marks

Formability of Ti-1.5Fe Thi k 0 3Formability of Ti 1.5Fe Thickness=0.3mm

80

100

80

100

%)

Gr 160

80

60

80bi

lity(

%

(press oil)No Crack at all

(100%)

Gr.1

Ti-1.5Fe(adding lubricant film)20

40

20

40

Form

a

(with lubricant film)

(press oil)

Ti-1.5Fe0

0 1 2 3 40

0 1 2 3 4

(press oil)

Cracks at some apex(83%)

Forming height (mm)Forming height (mm)

14

Formability of Ti-1.5Fe, if well lubricated, is as good as Gr.1’s

Requirements to titanium for PHEq

PHE d S l tiPHE needs

-Low cost & Stable mass supply

Solution

-New extracting/refining methods >Permissible impuritiesStable mass supply

-Higher performance

>Permissible impurities

-Higher strength with-Higher performance>Higher pressure>Higher temperature>Higher heat transfer rate

-Higher strength withgood press-formability

-Simulation technique for plateHigher heat transfer rate Simulation technique for plate forming considering formingproperties of the material

15

More accurate forming simulation

600

600600

600

g

-Precise data at omni direction-Stress-strain curves(Left Fig.)

300

400

500

tress

/MP

a Ti-1.5Fe500

300400

ess

/MPa

300

400

500

tress

/MP

a Ti-1.5Fe500

300400

ess

/MPa

( g )-r-value-strain curves-Yield surface data

-Constitutive equationf d i ld f d

100

200

300

True

st

0.0° 26.6° 45.0° 63.4°90 0°

TensileDirectionfrom R.D.

Gr.1 class300200100Tr

ue s

tre

100

200

300

True

st

0.0° 26.6° 45.0° 63.4°90 0°

TensileDirectionfrom R.D.

Gr.1 class300200100Tr

ue s

trefrom measured yield surface data

-Friction condition

0.0 0.1 0.2 0.3 0.40

Logarithmic plasitc strain εp

90.0

Axial logarithmic plastic strain ep0 0.1

00.2 0.3 0.4

0.0 0.1 0.2 0.3 0.40

Logarithmic plasitc strain εp

90.0

Axial logarithmic plastic strain ep0 0.1

00.2 0.3 0.4

FEM calculation FEM calculation for sheet formingfor sheet forming

Tensile strength data at various direction

16

Simulation during square deep drawingg q p gdirection 45°

0 50

0.51

mm

)

Depth=10mm

R.D.0.48

0.49

0.50

hick

ness

(m

Calculationmeasurement

0.470 20 40 60 80 100

Distance from center (mm)

Th measurement

Depth=20mm

0.58mm

0.54mm

0 50

Thickness of drawing（H=10, 20mm)0 48

0.50

0.52

ness

(mm

)

Depth 20mm0.50mm

0.46mm

0.44

0.46

0.48

0 20 40 60 80 100

Thic

knCalculationmeasurement

<Gr.1>thickness:0.50mm

17

Distance from center(mm)

Good agreement with calculated and experimental data

Simulation of Herringbone type forming0.30mm

0 25mm

g yp g

Thinnest PartSecond0.25mm

0.20mm

0.15mm

Second thinnest

thickness

Thickness order 12<Ti-1.5Fe> thickness:0.30mm

Thickness order ….. 12

1

18Thinnest part is correspondent with the crack area

2

Conclusion

A l d l d ll h d b l- A newly developed alloy shows good balance of strength and formability for high performance PHEPHE

- FEM simulation considering the omni-directional gmechanical properties of titanium and new alloy shows good agreement with experimental results.

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Kobe Steel's original alloysKobe Steel s original alloys

-Exhaust system KSTI-1.2ASNEXKSTI-1 5AL

-Structural materials: Plate/Sheets KS TI-9

AerospaceAutomotives KSTI 1.5AL

-Connecting Rod KS8-1-1CKS EL-FKS EL-FII

E i l KS72SiC

Plate/Sheets KS TI-9Bars/Forgings KS EL-F

KS EL-FII

Industries-Engine valves KS72SiCKS6-4-4-1TA

-Suspension Spring KS8-8-2-4-3-Chemical Plants KSAKOT

KS50TA-PHE KS1.5FE

Industries

-Medical Implants KS6-2-1KS15-5-3

OthersTokyo Head Office Titanium Sales Dept. Overseas Section

T l +81 3 5739 6203 (Di l i )-Golf Club KSTI-9KS EL-FKSTI15-0-3,….

-Watches Cutleries KS100

Tel +81-3-5739-6203 (Dial-in)Titanium Technology Dept.

Tel +81-3-5739-6211 (Dial-in)Web Site

htt // k b l j / li h/tit /

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Watches,Cutleries KS100KS120SI

http://www.kobelco.co.jp/english/titan/

Thank you for your kind attention!

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