Smart Degassing In Aluminium Alloys Alminyum Alamlarnda Etkili Gaz - - PowerPoint PPT Presentation

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Smart Degassing In Aluminium Alloys Alminyum Alamlarnda Etkili Gaz - - PowerPoint PPT Presentation

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Smart Degassing In Aluminium Alloys Alminyum Alamlarnda Etkili Gaz Giderme Ronny Simon Roger Kendrick (Foseco) 5.Oturum: Dkm Teknolojileri Demir D 5th Session: Casting Technologies Non Ferrous Oturum Bakan/

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SLIDE 1

«Smart Degassing In Aluminium Alloys» «Alüminyum Alaşımlarında Etkili Gaz Giderme»

Ronny Simon Roger Kendrick (Foseco)

Oturumlarda yer alan sunumlar 15 Eylül 2014 Pazartesi tarihinde kongre web sayfasına (kongre.tudoksad.org.tr) yüklenecektir.

5.Oturum: Döküm Teknolojileri Demir Dışı 5th Session: Casting Technologies Non Ferrous

Oturum Başkanı/Session Chairman: Can Demir (Componenta Döküm. Tic. San. A.Ş.- Alüminyum)

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SLIDE 2

Ronny Simon Roger Kendrick Foseco Foundry Division Europe

Intelligent Degassing – Studies on Controlling the Hydrogen Removal from Aluminium

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SLIDE 3

Agenda

2

  • Hydrogen solubility and removal
  • Mixing purpose and rotor functions in aluminium degassing
  • Pumping vs. Non-pumping designs
  • Homogenising Capability of Rotors in Water
  • Degassing Efficiency over Rotor Service Life
  • Intelligent Degassing - SMARTT
  • Summary and Conclusions
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SLIDE 4

Hydrogen Solubility

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  • Gas porosity in aluminium is a well known phenomena for many years
  • Unacceptable surface quality
  • Surface blistering after heat treatment
  • Leakage problems
  • Reduced mechanical properties
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SLIDE 5

Factors Influencing Hydrogen Solubility

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  • Temperature (liquid – solid)

0,0001 0,001 0,01 0,1 1 10 200 300 400 500 600 700 800 900

Hydrogen Content in ml/100 g Al

Temperature in °C

Hydrogen Solubility

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SLIDE 6

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  • Temperature (liquid – solid)
  • Alloy composition

Magnesium increases solubility Copper, silicon and zinc degrease solubility

Factors Influencing Hydrogen Solubility

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SLIDE 7

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  • Temperature (liquid – solid)
  • Alloy composition
  • Ambient conditions

Factors Influencing Hydrogen Solubility

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SLIDE 8

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Principle of Hydrogen Removal

Start with a dry inert gas bubble Establishing a local equilibrium between:

  • Hydrogen concentration in diffusion layer
  • Partial pressure of hydrogen in the inert gas bubble

Hydrogen concentration in inert gas bubble increases

H Atom, solved in melt H2 Molecule within inert gas bubble Inert gas Boundary layer of diffusion

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SLIDE 9

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Mixing purpose and rotor functions

  • Small inert gas bubbles for bigger surface
  • Slow vertical bubble movement
  • Homogeneous bubble distribution
  • Homogeneous temperature and alloying element distribution

Lance Porous block Rotary degassing

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SLIDE 10

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Mixing purpose and rotor functions

  • Rotor characterisation
  • Homogenising
  • Gas dispersion
  • Suspension of solids
  • Liquid-liquid-blending
  • Heat transfer
  • Reactions
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SLIDE 11

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Pumping rotor Non-pumping rotor

Pumping vs. Non-pumping designs

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SLIDE 12

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Homogenising Capability in Water

Pumping rotors Non-pumping rotor Type XSR Type FDR Trial procedure: 350 rpm rotor speed Pictures taken 4 seconds after ink addition

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SLIDE 13

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SLIDE 14

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  • Water filled Perspex tank

(60 cm diameter, 90 cm depth)

  • 250 – 260 kg of water
  • 8 type T thermocouples
  • Addition of 7000 ml of hot water @80 °C
  • Rotors run at 400 rpm

Homogenising Capability in Water

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SLIDE 15

Non-pumping rotors

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Homogenising Capability in Water

Pumping rotors

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SLIDE 16
  • Design, shape and size significantly impact the ability to degas aluminium

melts.

  • Does each particular rotor perform well throughout the entire service

life?

  • What is the true valuable life of a rotor and therefore when should a

rotor be changed?

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Efficiency over Rotor Service Life

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SLIDE 17

Trial procedure: 200 kg crucible furnace with AlSi10Mg at 750 °C 175 mm diameter rotor at 320 rpm and 15 l/min nitrogen 52 – 54 % rH and 25 °C Hydrogen curves were recorded by the ALSPEK H hydrogen analyser.

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Efficiency over Rotor Service Life

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SLIDE 18

Comparison between new rotors

17 0,05 0,10 0,15 0,20 0,25 0,30 0,35 0,40 0,45 50 100 150 200 250 300

Hydrogen in ml/100g Al Treatment time in seconds

Pumping Non-pumping 0,08 ml/100g Limit

Target limits: Pumping rotor: 0,08 ml H2 / 100 g Al Non-pumping rotor: 0,10 ml H2 / 100 g Al

Efficiency over Rotor Service Life

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SLIDE 19

Pumping rotor New After 25 % After 50 % After 75 % Overdue

  • f total service life

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Efficiency over Rotor Service Life

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SLIDE 20

New After 25 % After 50 % After 75 % Overdue

  • f total service life

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Efficiency over Rotor Service Life

Pumping rotor

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SLIDE 21

New After 10 % After 75 % After 95 %

  • f total service life

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Efficiency over Rotor Service Life

Non-pumping rotor

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SLIDE 22

New After 25 % After 50 % After 95 %

  • f total service life

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Efficiency over Rotor Service Life

Non-pumping rotor

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SLIDE 23

Comparison of Results Limit

[ml H2/100 g Al]

0,08 0,10 Time to limit new rotor

[s]

230 220 Time to limit used rotor

[s]

250 260 Fading over service life [%] < 10 > 20 Pumping rotors provide consistent degassing efficiency because they compensate a loss in outer diameter and rounded edges by oxidation of the graphite actually increasing the pumping chamber size. Foundries must define a maximum number of cycles or limit samples.

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Efficiency over Rotor Service Life

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SLIDE 24

Intelligent Degassing - SMARTT

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  • Extensive laboratory work has enabled Foseco and tsc

to develop a mathematical model which can be the basis of an intelligent system

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SLIDE 25

Intelligent Degassing - SMARTT

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  • This model recognises changes in external conditions

such as ambient temperature, atmospheric humidity and rotor wear, and can then catered for them during the subsequent metal treatment cycle.

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SLIDE 26

Intelligent Degassing - SMARTT

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SLIDE 27

Summary and conclusions

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  • Pumping Rotors are far more efficient than non-pumping rotors in terms
  • f mixing, improving metal quality, offering melt quality consistency and

reducing the cost per treatment.

  • Currently the efficiency loss experienced must be added to the treatment

time for new rotors to reach the limit throughout their life.

  • Degassing with a Foundry Degassing Unit using the mathematical model
  • ffers a further step forward in Process Control. SMARTT enables

foundries to run the degassing process independent from operator involvement and getting reliable and constant results.

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SLIDE 28
  • Ronny Simon
  • Vesuvius GmbH

Foseco Foundry Division Gelsenkirchener Strasse 10 D-46325 Borken Germany

  • Ronny.Simon@foseco.com
  • www.foseco.com

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  • Roger Kendrick
  • Foseco UK Ltd.

Drayton Manor Business Park Tamworth, Staffordshire B78 3TL United Kingdom

  • Roger.Kendrick@foseco.com
  • www.foseco.com

Additional information