Fundamentals of Solidification

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Fundamentals of Solidification

• Lecture 1 Metal Casting

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Outline

• Introduction
• Preparation of casting
• Component casting
• Ingot casting
• Continuous casting

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Introduction

• Solidification and casting
• Solidification is the process of transformation
  form a liquid phase to a solid phase
• WikiAnswers
• Casting is a mass production process which
  involves molten materials being poured into a
  mold, allowed to solidify and then extracted for
  use. tech-faq

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Introduction

• History of casting
• Stone age
• Copper was used from 6000 years ago
• Bronze age
• People knew how to make copper-tin alloys
• Bronze can also be made by adding Al, Zn, Si, Ni,
  Mn,
• Iron is more expensive than gold

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Bronze
France, 15001300 BC.
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Bronze
China, 16001046 BC
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Bronze
National Museum of Korea
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Introduction

• History of casting (continued)
• Iron age
• Steel is an alloy consisting mostly of iron, with
  a carbon content between 0.2 and 2.04 by
  weight.
• High melting point Fe 1535 ?C Cu 1083 ?C Si
  1410 ?C Al 660 ?C Sn 232 ?C
• Steel is stronger than bronze, and easy to sharp.

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Introduction

• History of casting (continued)
• Modern casting
• After the middle of 19th century, materials
  qualities were improved by plastic forming,
  forging and rolling.
• From the middle of 20th century, continuous
  casting has been widely applied.

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Preparation of casting

• Preparation of liquid metal
• Get all materials ready
• Make suitable composition
• Melt materials
• Liquid metal protection
• Preparation of casting
• Store and transfer liquid ladle
• moulds

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Component casting

• Melt metal
• Transfer to ladle
• Transferred from ladle to mould
• Solidified

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Pre-casting moulding
Ancient mould for casting a axe
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Pre-casting Moulding

• Principle for the production of moulds
• Pattern Reproduction of metal component is made
  by wood, plastic, metal or other suitable
  materials.
• Flask The mould frame is called a flask. The
  pattern is placed in flask.
• Filling The flask is then filled with moulding
  mixture which is then compact. Moulding mixture
  consists of sand, a binder and water
• Finishing Pattern is removed and leave cavity
  and core.

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Pre-casting Moulding

• Summary of moulding
• Cavity
• Core
• Casting gate or gating system
• Feeder compensate for the solidification
  shrinkage in the metal.
• Mould is knocked out
• Feeders and inlet are removed through cutting or
  oxygen shearing

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Component casting
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Component casting

• Sand mould casting
• Able to cast 0.1kg 105kg components, suitable
  for single castings as well as for large-scale
  casting, can use hand moulding and large-scale
  machine moulding.
• Advantage cast most metal, complicated
  component, low initial cost.
• Disadvantage poor dimensional accuracy, poor
  surface smoothness.

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Component casting

• Shell mould casting
• High dimensional accuracy, good reproduction of
  the shape of the component, good surface
  smoothness, complicated core possible, can cast
  thin walls
• High code, maximum mass 60-70kg. Large amount to
  profitable

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Component casting
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Casting in permanent moulds

• Moulds are made of cast iron or special steel
  alloy with good resistance to high temperature.
  Mainly used in aluminum, magnesium and zinc
  alloy, difficult for high melting point alloys.

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Die casting
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Thixomoulding casting

• Cast semisolid slurry

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Ingot casting

• Metal melt is poured from ladle into moulds where
  it solidifies

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Ingot casting

• Downhill casting
• Uphill casting
• Advantage?
• Disadvantage?

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Continuous casting

• 1856 Henry Bessemer proposed
• 1930-1940 Applied in common production of
  nonferrous alloy
• 1943 steel casting by German scientist Junghans
• gt90 world production of steel

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Continuous casting

• Ladle
• Stopper
• Dispenser
• Shroud
• Mold
• Roll support
• Turning Zone
• Shroud
• Bath level
• Meniscus
• Withdrawal unit
• Slab

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Continuous casting
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Continuous casting
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Continuous casting
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Continuous casting
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Continuous casting
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References

• Hasse Fredriksson and Ulla Åkerlind, Materials
  Processing during Casting, Wiley, (2006).
• M.C. Flemings, Solidification processing, (1976).
• http//cml.postech.ac.kr/rqin/gift702/

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