The ultimate goal of a manufacturing engineer is to produce steel/metal components with required geometrical shape and structurally optimized for a given application. One of the method is the deformation processing. Deformation processing exploits the

1
INTRODUCTION

• The ultimate goal of a manufacturing engineer is
  to produce steel/metal components with required
  geometrical shape and structurally optimized for
  a given application. One of the method is the
  deformation processing. Deformation processing
  exploits the ability of steel to flow plastically
  without altering the other properties.

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INTRODUCTION

• The required forces are often very high. Cast
  ingots, slabs, blooms and billets are reduced in
  size and converted into plates, sheets, rods and
  others. These forms experience further
  deformation to produce the desired products
  formed by processes such as forging, extrusion
  and other sheet metal forming. The deformation
  may be bulk flow in three dimensions, simple
  shearing, simple bending, or any combination of
  these and other processes. The stresses could
  either be tensile or compressive or shear or
  combination of them. In this connection the steel
  chemistry and cleanliness are important factors
  for deformation processing.

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INTRODUCTION

• Some aspect of deformation processing will be
  discussed. This is given to appreciate the
  efforts of steelmakers or any other metalmakers
  in producing quality steels and/or metals.
• Deformation processing can be carried out either
  under hot or cold condition.

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HOT AND COLD PROCESSES (WORKING)
Hot Working   The distinction between hot
working and cold working does not depends solely
on the temperature, but rather on the processing
temperature with respect to the material
recrystallization temperature. When the
processing temperature of the mechanical
deformation of steel is above the
recrystallization temperature, the process is
termed as hot working otherwise, it is cold
working.   For hot working processes, large
deformation can be successively repeated, as the
metal remains soft and ductile. The hardness of
the material cannot be controlled after hot
rolling and it is a function of chemical
composition and the rate of cooling after
rolling. The hardness is generally lower than
that of cold rolling and the required deformation
energy is lesser as well. However most metal will
experience some surface oxidation resulting in
material loss and poor final surface finish.  
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HOT WORKING

• Hot working does not produce strain hardening.
  Hence no increase in either yield strength or
  hardness occurs. In addition yield strength
  decreases as temperature increases and the
  ductility improves.
• Hot working can be used to drastically alter the
  shape of metals without fear of fracture and
  excessively high forces.

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HOT WORKING

• Elevated temperatures promote diffusion that can
  remove chemical inhomogeneties pores can be
  welded or reduced in size during deformation.
• The dendritic grain structure, small gas cavities
  and shrinkage porosity formed during
  solidification in large sections can be modified
  by hot working to produce a fine, randomly
  oriented, spherical-shaped grain structure which
  results in a net increase in ductility and
  toughness.

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HOT WORKING

• Hot working results in reorientation of
  inclusions or impurity particles in the metal
  with the result that an impurity originally
  oriented so as to aid crack movement through the
  metal can be reoriented into a crack arrestor
  configuration.

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HOT AND COLD PROCESSES (WORKING)

• Cold Working
• Cold working processes allow desirable metal
  qualities that cannot be obtained by hot working,
  such as eliminating errors attending shrinkage.
  As such, a much more compact and higher
  dimensional accuracy metal can be obtained with
  cold working. Furthermore, the final products
  have a smoother surface (better surface finish)
  than those of hot working and the strength,
  hardness as well as the elastic limit are
  increased. However, the ductility of the metal
  decreases due to strain hardening thus making the
  metal more brittle. As such, the metal must be
  heated from time to time (annealed) during the
  rolling operation to remove the undesirable
  effects of cold working and to increase the
  workability of the metal.

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COLD WORKING

• Some advantages of cold working are
• No heating is required
• Better surface finish and superior dimensional
  control are achieved
• Strength, fatigue, and wear properties are
  improved
• Directional properties can be imparted

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COLD WORKING

• Disadvantages of cold working are
• Heavier forces are required
• Strain hardening occurs (may require intermediate
  annealing treatment to relieve internal stresses)
  
• Residual stresses may be produced
• For cold working, the ductility and the yield
  point stress of steel are important.

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FOUR BASIC BULK DEFORMATION PROCESSES

• ROLLING-Slab or plate is squeezed between
  opposing rolls
• FORGING-Work is squeezed and shaped between
  opposing dies
• EXTRUSION- Work is squeezed through a die
  opening, thereby taking the shape of the opening
• WIRE AND BAR DRAWING- Diameter of wire or bar is
  reduced by pulling it through a die opening

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SCHEMATICS
ROLLING SCHEMATICS
FORGING SCHEMATIC
EXTRUSION SCHEMATIC
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FORGING MOVIE
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ROLLING MOVIE