Mohammad Irfan, David Schwam (CWRU) Andy Karve, Randy Ryder (Neemak) Mike Cox, John Kubisch (GM)

Mohammad Irfan, David Schwam (CWRU)

Andy Karve, Randy Ryder (Neemak)

Mike Cox, John Kubisch (GM)

February, 2009

Part I: Review of Project Brief Part II: Initial Trials Part III: EDX & SEM Part IV: Introduction of cooling core Part V: DOE Conclusions Future Work

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Part - I

DOE setup to understand the effect of Process Parameters on Mechanical Properties of thickest section

Process Parameters: 1. Melt Handling : Melt Temperature, Pour

Temperature2. Injection: Slow shot velocity. Fast shot

velocity, intensification pressure3. Solidification: Die Temperature,

Temperature of casting at ejection, Cycle time

4. Water Quench5. T5 heat treatment

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5

Sept Oct Nov Dec Jan Feb Mar Apr May Jun

Project Kick-off

DOE

Final Report

Metall. & Mech. Testing

Process Testing

Process Testing

Metall. & Mech. Testing

Part - II

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Test specimens were taken from the center saddles on the underside of the block as indicated in the figure. Three specimens were taken from each saddle with two specimens coming from the edges of one side of the saddle and one specimen from the center of the opposite side.

Sampling

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9

10

11

FORD SPEC. 175 MPa

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FORD SPEC. 170 MPa

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FORD SPEC. 0.5 %

It is hard to relate mechanical properties with % area porosity

It does not mean that porosity does not effect mechanical properties. Efforts should be continued to minimize porosity.

DAS seems to be a better indicator of mechanical properties

Future efforts should be directed towards improving DAS

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Part - III

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Element Norm. wt. %

384 Spec. wt. %

Al 78.72 77-86

Si 13.13 10.5 – 12

Cu 3.32 3-4.5

Zn 1.43 3

Fe 0.86 1.3

Mn 0.21 0.5

Ni 0.13 0.5

Mg 0.65 0.1

Sn trace 0.35

Others remainder

remainder

Iron rich β phase Cu rich zones

Si Needles

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Dimpled Fracture Surface

Micro porosity

Large Pore

Crack

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Inclusion

Element

% wt.

C 5.5

O 0.6

Al 56.6

Si 18.4

Cl 0.1

Mn 1.2

Fe 3.2

Cu 7.1

Zn 5.6

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Limited Ductility (Dimples)

Cleavage fracture

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Limited Ductility (Dimples)

Transgranular brittle fracture of Fe rich β phase

Cleavage fracture

The EDX and SEM gave us a better picture of the microstructure of the die castings

Plate-like Fe rich β phase is known to act as obstruction to liquid metal flow

Cu rich “sludge” is known to act as porosity initiation sites

Fracture surface was in general “Cleavage” (brittle) with limited indications of ductility

Large pores acted as crack initiation sites during tensile tests

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Part - IV

Un-cooled core 38406 Cooled core 38407

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1. Two engine blocks, one with a cooled core and other with an un-cooled core

2. 5 journals from each engine block3. Journal 3 was sent sliced in the middle for measuring DAS across the

face4. Journals 1,2,4,5 were cut further to extract 2 tensile samples from

each journal

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Measurements starting from edge of hole (cooling core) every 1.5 mm till 15 mm (11 measurements). Then measurements every 3 mm till the right sectioned edge 12 mm (4 measurements)

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y = mx +cDAS = 0.5 x + 18

Initial Value

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Measurements starting from edge of hole (cooling core) every 1.5 mm till 13.5 mm (10 measurements).

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10 Measurements starting from edge of hole (cooling core) every 1.1 mm till 10 mm.

2 Measurements every 2.2 mm for 4.4 mm.

3 measurements every 1.1 mm starting from the bottom journal edge for 3.3 mm

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•Note: Cooling is not a 1 Dimensional Problem•The cooling effect measured in terms of DAS is a 3 D problem, with heat transfer taking place in all 3 directions•Solidification starts both at the core and journal ends, giving the minimum DAS

Journal side

Core side

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CORE EXTERNAL EDGE

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CORE EXTERNAL EDGE

UN COOLED CORE COOLED CORE

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B034: Cooled, No TiBor, Short Dwell, Quench E

B040: Un-Cooled, TiBor, Long Dwell, Quench W

Hyundai- I-4 38407 cooled core Wt: 22.7 kg

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Effect of Thermal Conductivity of the Shot Block

Material on Cooling Time of Biscuit at 950oF

0

5

10

15

20

25

30

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0 20 40 60 80 100 120 140

Thermal Conductivity(Btu/ft.h.F)

Coo

ling

Tim

e(s)

H13

Anvilloy

3C CuBe

Toolox 44

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40

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Part - V

VC Cooling Dwell TiBor QuenchOn Short No EOff Long Yes WOff Short No WOn Long No EOff Short Yes WOff Long No EOn Long Yes EOn Short Yes W

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VC Cooling

Dwell TiBor Quench

B034 On Short No E

B040 Off Long Yes W

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ID-304

Tensile (MPa)

Yield (MPa)

% Elong.

J1-F 265 209 1.2

J1-R 271 212 0.9

J2-F 264 214 1.2

J2-R 283 218 1.3

J4-F 265 203 0.9

J4-R 273 204 1.4

J5-F 235 211 1.4

J5-R 289 206 1.2

Ave 268 210 1.2

Spec

200 150 -

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ID-040

Tensile (MPa)

Yield (MPa)

% Elong.

J1-F 249 210 1.1

J1-R 281 210 1.4

J2-F 262 209 1.3

J2-R 262 199 1.1

J4-F 242 233 1.4

J4-R 256 212 1.4

J5-F 252 229 1.4

J5-R 202 - 0.5

Ave 251 215 1.2

Spec

200 150 -

B034: Cooled, No TiBor, Short Dwell, Quench E

B040: Un-Cooled, TiBor, Long Dwell, Quench W

The water cooled core reduces DAS and improves mechanical properties, however the cooling effect fades with increasing distance from the core

Higher cooling rates and deeper penetration can be achieved by using cores made of higher thermal conductivity alloys and/or higher flow rates

The grain refined engine block with no-cooling exhibited a fine DAS and improved mechanical properties

From our previous presentations, DAS can effectively be used as a predictor of Mechanical properties (Strong dependence: UTS & Elongation, Weak dependence: YS)

% Pore area is not a reliable predictor of mechanical properties due to the probabilistic and random nature of porosity at the section under observation

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1. Continue with DOE analysis2. Report Writing

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Thank You

Questions ?

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