2005 grey cast iron cylinder presentation

8/13/2019 2005 Grey Cast Iron Cylinder Presentation

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Grey Iron Cylinder InoculantFloat

Joe Licavoli Aaron Lueker

Dan SeguinPaul NelsonTerri Mullen

Andrew Zeagler


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Process Grey Iron was cast into many

different cylindrical moldswith varying height; 6,12, and20in

Inoculant was added to themelt to initiate nucleationsites for graphite flakes toform in the solid

The uniformity of flakesaffects the mechanicalproperties of the material

Type D/E Flakes 20 m Scale Bar

Type A/B Flakes 20 m Scale Bar


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Initial Defective Iron Sample

The hollow areainside of the solidifiediron sample is where

the Ferro-Silicateinoculant coagulated,leaving it un-reactedwith the iron.


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Considerations for the Grey IronCasting Process

Solidification - The cylinder may take too long tosolidify, giving the inoculant the opportunity tofloat

Flotation - The inoculant may flow almostcompletely to the surface before reacting withthe melt

Dissolution - The radius of the inoculant affectsits flotation. Since dissolution affects radius,dissolution may, in turn, affect flotation


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Our Groups Problems to solve

Grey Iron Cylinderproblems

Solidification Flotation Dissolution


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Solidification

Chvorinovs rule used to determinesolidification time.

Solidification from top determined usingNewtons Law of cooling. Inconsistencies in calculation with reality. Did not account heat flow from sides through

top.


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Solidification from Mold Walls

Calculate energy conducted away from themetal to the mold during solidification

Excess energy had two sources From the phase transformation From superheating

This energy had to be conducted away fromthe metal through mold surfaces


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Solidification from the Mold Wall

Chvorinovs rule yields the following equationfor time through Fouriers Law of Conduction:

Time comes out to be 8.9 minutes

t s T p M Q t T p 2

T m T o 2

22 A

2 M2


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Effect of Pour Temperature

1400 1600 1800520

530

540

ts T p

T

Notice: Not very temperature dependent


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Solidification from Top

Heat dissipated by convection through top of mold Modeled using Newtons Law of Cooling

Heat flux found, multiplied by solidification time and

energy liberated to find depth of solidification as afunction of pour temperature

D sol T p qV m

C Metal T p T m A m1

H f Metal t im

D sol 1773K ( ) .529


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Inconsistencies

The calculated solidification distance fromthe top was inconsistent with actual results 1.5- 2.5 in reality

Rough estimate from casting

Did not account for heat flow from sides

through top Limited models for heat transfer coefficient in

calculating heat flux


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Magmasoft Simulations Modeled solidification to

understand where inoculantswould have the most time to float

Limitations of the universitiesversion of Magmasoft did not

allow for the modeling of the Ironcontaining inoculant particles

Knowing the temperature andgeometries of the un-solidifiedsections as time passes could

allow for a more accuratecalculation of final inoculantdistribution


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Cooling Rate Control of Flake Spacing

Flake spacing is controlled bycooling rate

Since the cylinder has a constant

cooling rate, there is uniform flakespacing throughout the cylinder

This would be a good medium toattempt an experiment todetermine the relationship ofinoculant mixing time vs. flakespacing (i.e. fade)


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Simulated Inoculant Mixing


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Flotation

The inoculant is mixed in with the liquidgrey iron as it is poured into the transfercrucible

From here it is poured into the desiredmold

As the mold solidifies, the particles ofinoculant begin to float because they areless dense than the grey iron


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Flotation contd.

The following calculations were used fromexample 3.3 (Gaskell)

Terminal Velocity-

Also the critical radius for flotation can be

found by

R T p L x 9 v t T p L x

2 Metal Inoculent g.

v t T p L x L xt s T p L


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Flotation contd. With this data we can also find the Reynolds

number which will show whether the flow islaminar or turbulent

The Reynolds number will be less than 0.1,exhibiting laminar flow. (This confirms that ourequation for terminal velocity is valid)

R e T p L x 2 R T

p L x

v

t T

p L x

Metal


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Flotation cont.

Figure F.1 In this figure the

critical particle

radius is found asthe length of thecylinder isincreased 0 0.1 0.2 0.3 0.4 0.55 10

6

1 10 5

1.510 5

2 10 5

2.510 5

2.325 10 5

9.181 10 6

R T p

L x

0.60.015 L


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Flotation Results

Flotation problems -Most of the particles

floated to the

surface withoutreacting with thegrey iron melt


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Dissolution

Changes in particle diameter may influenceflotation time

Dissolution equation derived from analogous

heat transfer equations in Gaskell

R t

h D Isi Lsi atSI


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Dissolution contd.

Equations derived from Gaskell lead tosolution for mass transfer coefficient h D

hD

2 .4 R e T p L x 0.5

.06R e T p L x 2

3

1

poise

2.410 9

.4

s

.25

2 R T p L x DSi

s


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Problems with Result

Calculations do not agree with experiment Unavailable ternary phase diagram forced

approximation from binary phase diagram

Viscosity difference is unknown

hD

2 .4 R e T p L x 0.5

.06R e T p L x 2

3

1

poise

2.410 9

.4

1

1

.25

2 R T p L x DSi

R th D Isi Lsi

atSI

Particle radius ~tenths of mm

R = .2363 mm/s


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A More Likely Explanation

Interfacial resistance may account fordifferences

Solidification at inoculant surface mayserve as a barrier to further atomicdiffusion

Conclusion: Better numbers andconsideration of interfacial resistancecould accurately model dissolution.


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Conclusions Based on solidification model in conjunction withflotation model, inoculant particles in our

particular application would have ample time tofloat.

The flotation of incoculant did in fact lead to thenumerous pores located on the surface of thecylinder.

Dissolution could be a huge factor in removing

inoculant from the molten iron before it floated,but interfacial considerations need to be taken tounderstand the complete dynamics.


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References

Metal Casting Handbook For MY4130 byKarl B. RundmanDavid R. Gaskell An Introduction to

Transport Phenomena in MaterialsEngineering

SAH Free Consulting Firm Bring all yourproblems to me, Ill help ya out. unless

yer a union guy The offices of Lord Chadwick Boyle III & Sir

Chester Fairfax.


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Questions

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2005 grey cast iron cylinder presentation

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