Examples of Fractography in Other Materials

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Examples of Fractography in Other Materials
Professor M Neil James mjames_at_plymouth.ac.uk Depa
rtment of Mechanical Marine Engineering Universi
ty of Plymouth Drake Circus, Plymouth PL4
8AA ENGLAND
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Contents Use the hyperlinks to navigate around
this resource

• WC-Co Compression and tensile fatigue
• 316L stainless steel SCC
• Fatigue in polycarbonate
• Fast fracture in polycarbonate

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WC-Co Compression and tensile fatigue
6 Co Grade T6 ?Rupture 2190 MPa - average
grain size 1.8 ?m
The line indicates the transition between regions
of compression fatigue (lower half) and tensile
fatigue (upper half) Original magnification
shown by micron bar
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WC-Co Compression and tensile fatigue
6 Co Grade T6 ?Rupture 2190 MPa - average
grain size 1.8 ?m
Compression fatigue at higher magnification WC
grains are rounded and Co tear ridges are less
frequent Original magnification shown by micron
bar
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WC-Co Compression and tensile fatigue
6 Co Grade T6 ?Rupture 2190 MPa - average
grain size 1.8 ?m
Tensile fatigue at higher magnification WC
grains are more angular and Co tear ridges are
more evident Original magnification shown by
micron bar Back to Contents
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316L stainless steel - SCC
0.033C 1.44Mn 0.44Si 18.4Cr 8.6Ni 0.016P
0.010S ?YS 205 MPa in annealed state Vickers
hardness 235
2 mm thick, 120 mm diameter seam welded pipe used
to transport glucose solution Cracking associated
with weld inner surface of pipe shown here
significant crack branching
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316L stainless steel - SCC
0.033C 1.44Mn 0.44Si 18.4Cr 8.6Ni 0.016P
0.010S ?YS 205 MPa in annealed state Vickers
hardness 235
2 mm thick, 120 mm diameter seam welded pipe used
to transport glucose solution Cracking associated
with weld outer surface of pipe shown here
less crack branching Implication glucose is
cause of problem, not external lagging
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316L stainless steel - SCC
0.033C 1.44Mn 0.44Si 18.4Cr 8.6Ni 0.016P
0.010S ?YS 205 MPa in annealed state Vickers
hardness 235
2 mm thick, 120 mm diameter seam welded pipe used
to transport glucose solution Fracture surface
shows brittle appearance not fatigue crack
growth
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316L stainless steel - SCC
0.033C 1.44Mn 0.44Si 18.4Cr 8.6Ni 0.016P
0.010S ?YS 205 MPa in annealed state Vickers
hardness 235
2 mm thick, 120 mm diameter seam welded pipe used
to transport glucose solution Have 'feathery'
cleavage facets present Implication SCC,
although detrimental species not clear
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316L stainless steel - SCC
0.033C 1.44Mn 0.44Si 18.4Cr 8.6Ni 0.016P
0.010S ?YS 205 MPa in annealed state Vickers
hardness 235
2 mm thick, 120 mm diameter seam welded pipe used
to transport glucose solution Pipe operates at
60C diagram indicates that chloride SCC occurs
at this temperature in acid solutions with 104
ppm of chlorides present Back to Contents
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Fatigue in polycarbonate
?YS 20 MPa (initial cyclic yield) - annealed
state 2 mm thick plate
R 0.5 Notch root is at the left of the picture
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Fatigue in polycarbonate
?YS 20 MPa (initial cyclic yield) - annealed
state 2 mm thick plate
R 0.5 Near the notch root
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Fatigue in polycarbonate
?YS 20 MPa (initial cyclic yield) - annealed
state 2 mm thick plate
R 0.5 Near the notch root The marks are not
fatigue striations
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Fatigue in polycarbonate
?YS 20 MPa (initial cyclic yield) - annealed
state 2 mm thick plate
R 0.5 This position is 7.5 mm from the notch
root
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Fatigue in polycarbonate
?YS 20 MPa (initial cyclic yield) - annealed
state 2 mm thick plate
R 0.5 This position is 17.5 mm from the notch
root The marks are not fatigue striations they
probably relate to craze size ahead of the crack
tip
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Fast fracture in polycarbonate
?YS 20 MPa (initial cyclic yield) - annealed
state 2 mm thick plate
This shows typical fast fracture in the
PC Features are very similar to fatigue Back to
Contents