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Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
• Crystal structures, grains and grain boundaries, plastic
deformation, and thermal effects.
• Characteristics and applications of cold, warm, and hot
working of metals.
• Ductile and brittle behavior of materials, modes of failure, and
the effects of various factors on fracture behavior.
• Physical properties of materials and their relievance to mfg
processes.
• General properties and engineering applications of ferrousand nonferrous metals and alloys.
Chapter 3: Structure and Mfg. Properties of Metals
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Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Turbine Blades
Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
FIGURE 3.1 Turbine blades for jet engines, manufactured by three different methods: (a) conventionally
cast; (b) directionally solidified, with columnar grains, as can be seen from the vertical streaks; and (c)
single crystal. Although more expensive, single-crystal blades have properties at high temperatures that
are superior to those of other blades. Source: Courtesy of United Technologies Pratt and Whitney.
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Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Common Crystal Structures
FIGURE 3.2 The body-centered cubic (bcc) crystal
structure: (a) hard-ball model; (b) unit cell; and (c) single
crystal with many unit cells. Common bcc metals include
chromium, titanium, and tungsten. Source: After W.G.
Moffatt.
FIGURE 3.3 The face-centered cubic (fcc) crystal
structure: (a) hard-ball model; (b) unit cell; and (c) singlecrystal with many unit cells. Common fcc metals include
aluminum, copper, gold and silver.Source: After W.G.
Moffatt.
FIGURE 3.4 The hexagonal close-packed (hcp) crystal
structure: (a) unit cell; and (b) single crystal with many
unit cells. Common hcp metals include zinc, magnesium
and cobalt. Source: After W.G. Moffatt.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Plastic Deformation in Crystals
FIGURE 3.5 Permanent deformation of a single crystal under a tensile load. The highlighted grid of atoms emphasizesthe motion that occurs within the lattice.(a) Deformation by slip. The b/a ratio influences the magnitude of the shear
stress required to cause slip. Note that the slip planes tend to align themselves in the direction of pulling. (b)
Deformation by twinning, involving generation of a “twin” around a line of symmetry subjected to shear. Note that the
tensile load results in a shear stress in the plane illustrated.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Shear Stress at Atomic Scale
FIGURE 3.6 Variation of shear stress in moving a plane of
atoms over another plane.
Shear stress:
Leads to:
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Slib Bands in a Single Crystal
FIGURE 3.7 Schematic illustration of slip lines and slipbands in a single crystal subjected to a shear stress. A slip
band consists of a number of slip planes. The crystal at the
center of the upper drawing is an individual grain surrounded
by other grains.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Normal Stress in a Single Crystal
FIGURE 3.8 Variation of cohesive
stress as a function of distance
between a row of atoms.
Work:
Leads to:
This is ideal or theoretical tensile strength
of metals based on pure atomic cohesion
strength. Actual UTS is likely
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Crystal Defects
FIGURE 3.9 Various defects in a single-
crystal lattice. Vacancy (point defects)Source: After W.G. Moffatt.
FIGURE 3.10 (a) Edge dislocation (1D), a linear
defect at the edge of an extra plane of atoms. (b)Screw dislocation, a helical defect in a three-
dimensional lattice of atoms. Screw dislocations
are so named because the atomic planes form a
spiral ramp. Grain or phase boundaries (2D), voids
or inclusions ((3D).
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Movement of Edge Dislocation
FIGURE 3.11 Movement of an edge dislocation across the crystal lattice under a shear stress.
Dislocations help explain why the actual strength of metals is much lower than that predicted by
atomic theory.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Grains During Solidification
FIGURE 3.12 Schematic illustration of the various stages during solidification of molten metal. Each small
square represents a unit cell. (a) Nucleation of crystals at random sites in the molten metal. Note that the
crystallographic orientation of each site is different. (b) and (c) Growth of crystals as solidificationcontinues. (d) Solidified metal, showing individual grains and grain boundaries. Note the different angles at
which neighboring grains meet each other. Source: After W. Rosenhain.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Tensile Stress in Polycrystalline
Material
FIGURE 3.13 Variation of tensile stress across aplane of polycrystalline metal specimen subjected to
tension. Note that the strength exhibited by each
grain depends on its orientation.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Grain Sizes
TABLE 3.1 Grain sizes.
ASTM Grain Size Number: n is ASTM grain-size number
N is the number of grains per sq inch at a magnificationof 100X (equal to 0.01 sq inch or 0.0645 sq mm)
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Embrittlement & Plastic Deformation
FIGURE 3.14 Embrittlement of copper by lead
and bismuth at 350°C (660°F). Embrittlement
has important effects on the strength, ductility,
and toughness of materials. Source: After W.
Rostoker. When close atomic contact with
certain low-melting-point metals, weakening the
grain boundaries, may result to crack under
very low stress.
FIGURE 3.15 Plastic deformation (cold work) of
idealized (equiaxed) grains in a specimen subjected
to compression, such as is done in rolling or forging
of metals: (a) before deformation; and (b) after
deformation. Note the alignment of grain boundaries
along a horizontal direction.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Crack Due to Bulging
FIGURE 3.16 (a) Illustration of a crack in sheet metal subjected to bulging, such as by
pushing a steel ball against the sheet. Note the orientation of the crack with respect to therolling direction of the sheet. This material is anisotropic. (b) Aluminum sheet with a crack
(vertical dark line at the center) developed in a bulge test. Source: Courtesy of J.S. Kallend,
Illinois Institute of Technology.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Recovery, Recrystallization
and Grain Growth
FIGURE 3.17 Schematic illustration of the effects
of recovery, recrystallization, and grain growth on
mechanical properties and shape and size of
grains. Note the formation of small new grains
during recrystallization. Source: After G. Sachs.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Recrystallization
FIGURE 3.19 The effect of prior cold work on the recrystallized grain
size of alpha brass. Below a critical elongation (strain), typically 5%, no
recrystallization occurs.
FIGURE 3.18 Variation of strength
and hardness with recrystallization
temperature, time, and prior cold
work. Note that the more a metal is
cold worked, the less time it takes
to recrystallize, because of the
higher stored energy from cold
working due to increased
dislocation density.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Surface Roughness; Homologous
Temperature
FIGURE 3.20 Surface roughness on the
cylindrical surface of an aluminum specimen
subjected to compression. Source: A. Mulc and S.Kalpakjian. Grain growth, larger grain size, results
to rough surface appearance, orange-peel effect.
TABLE 3.2 Homologous Temperature Ranges for
Various Processes. T is working temperature andTm is the melting point of the metal (abs. scale).
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Failure
FIGURE 3.22 Schematic illustration of the types of
fracture in tension: (a) brittle fracture in
polycrystalline metals; (b) shear fracture in ductile
single crystals (see also Fig. 3.5a); (c) ductile cup-
and-cone fracture in polycrystalline metals (see
also Fig. 2.2); (d) complete ductile fracture in
polycrystalline metals, with 100% reduction of area.
FIGURE 3.21 Schematic illustration of types of
failure in materials: (a) necking and fracture of
ductile materials; (b) buckling of ductile materials
under a compressive load; (c) fracture of brittle
materials in compression; (d) cracking on the
barreled surface of ductile materials incompression. (See also Fig. 6.1b)
General types of failure: (1) fracture: ductile/brittle
(2) buckling.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Ductile Fracture Surface
FIGURE 3.23 Surface of ductile fracture in low-carbon steel, showing dimples.Fracture is usually initiated at impurities, inclusions, or preexisting voids in the
metal. Source: K.-H. Habig and D. Klaffke. Photo courtesy of BAM, Berlin,
Germany.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Sequence in Necking and Fracture
FIGURE 3.24 Sequence of events in necking and fracture of a tensile-test specimen: (a) early stage of
necking; (b) small voids begin to form within the necked region; (c) voids coalesce, producing an
internal crack; (d) rest of cross-section begins to fail at the periphery by shearing; (e) final fracture
surfaces, known as cup-(top fracture surface) and-cone (bottom surface) fracture.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Effect of Inclusions
FIGURE 3.25 Schematic illustration of the deformation of soft and hard inclusions and
their effect on void formation in plastic deformation. Note that hard inclusions, because
they do not comply with the overall deformation of the ductile matrix, can cause voids.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Transition Temperature & Strain
Aging
FIGURE 3.26 Schematic illustration of
transition temperature. Note the narrow
temperature range across which the
behavior of the metal undergoes a major transition.
FIGURE 3.27 Strain aging and its effect on the shapeof the true-stress-true-strain curve for 0.03% C rimmed
steel at 60°C (140°F). Source: A.S. Keh and W.C.
Leslie. Accelerated strain aging by processing at a
higher temperature, e.g. blue brittleness for steels.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Brittle and Intergranular Fracture
FIGURE 3.29 Intergranular fracture, at two different
magnifications. Grains and grain boundaries are
clearly visible in this micrograph. The fracture path is
along the grain boundaries. Mag 100X and 500X
Source: Courtesy of Packer Engineering.
FIGURE 3.28 Typical fracture surface of steel
that has failed in a brittle manner. The fracture
path is transgranular (through the grains).
Compare this surface with the ductile fracture
surface shown in Fig. 3.23. Source: Courtesyof Packer Engineering.
Defects: Stress α 1 / sqrt(Crack Length)FIGURE 3.23 Surface
of ductile fracture
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Fracture Mode & Surface
FIGURE 3.30 Three modes of fracture for
cracks. Mode I has been studied extensively,
because it is the most commonly observed in
engineering structures and components. Mode IIis rare. Mode III is the tearing process; examples
include opening a pop-top can, tearing a piece of
paper, and cutting materials with a pair of
scissors.
FIGURE 3.31 Typical fatigue fracture surface on metals,
showing beach marks (each has series of striations/ridges).
Most components in machines and engines fail by fatigue and
not by excessive static loading. Source: Courtesy of Packer Engineering.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Fatigue
FIGURE 3.32 Reduction in fatigue strength of cast steels subjected to various surface-finishing operations. (a)
Effect of surface roughness. Note that the reduction is greater as the surface roughness and strength of the
steel increase. (b) Effect of residual stress, as developed by shot peening. Conversely, the following factors and
processes can reduce fatigue strength: decarburization, surface pits due to corrosion that act as stress raisers,
hydrogen embrittlement, galvanizing, and electroplating (Section 4.5.1). Stress-corrosion cracking (SCC).
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Physical Properties of Materials
TABLE 3.3 Physical Properties of Various
Materials at Room Temperature.
Resistance to Corrosion: (good or bad)
degradation, pitting, galvanic corrosion,
SCC, passivation
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Effect of Carbon on Steel Properties
FIGURE 3.33 Effect of carbon content on
the mechanical properties of carbon steel.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Annealed Stainless Steels
TABLE 3.4 Room-Temperature Mechanical Properties and Typical
Applications of Annealed Stainless Steels: corrosion resistance, highstrength and ductility, and high chromium content (+oxygen -> Cr-oxide).
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Tool & Die Materials
TABLE 3.5 Basic Types of Tool and Die
Steels.
TABLE 3.5 Typical Tool and Die Materials for Various
Processes.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Non-Ferrous Alloys in Aircraft Engine
FIGURE 3.34 Cross-section of a jet engine (PW2037) showing various
components and the alloys used in making them. Source: Courtesy of United
Aircraft Pratt & Whitney.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Aluminum Alloys
TABLE 3.7 Properties of Various Aluminum Alloys at Room Temperature
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Wrought Aluminum Alloys
TABLE 3.8 Manufacturing Properties and Typical Applications of Wrought Aluminum
Alloys.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Magnesium Alloys
TABLE 3.9 Properties and Typical Forms of Various Wrought Magnesium Alloys.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Copper & Brass
TABLE 3.10 Properties and Typical Applications of Various Wrought Copper and Brasses.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Wrought Bronzes
TABLE 3.11 Properties and Typical Applications of Various Wrought
Bronzes.
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Nickel Alloys
TABLE 3.12 Properties and Typical Applications of Various Nickel Alloys (All Alloy Names are Trade
Names).
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Nickel-Base Superalloys
TABLE 3.13 Properties and Typical Applications of Various Nickel-Base Superalloys at 870°C
(1600°F) (All Alloy Names Are Trade Names)
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Manufacturing Processes for Engineering Materials, 5th ed.Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Titanium Alloys
TABLE 3.14 Properties and Typical Applications of Wrought Titanium Alloys.
Problems 3.36, 3.39, 3.40
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