Post on 15-Jan-2016
Fractography Resource - mjames@plymouth.ac.uk1
Examples of Fractography in Other Materials
Professor M Neil Jamesmjames@plymouth.ac.uk
Department of Mechanical & Marine Engineering
University of Plymouth
Drake Circus, Plymouth PL4 8AA
ENGLAND
Fractography Resource - mjames@plymouth.ac.uk2
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
Fractography Resource - mjames@plymouth.ac.uk3
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
Fractography Resource - mjames@plymouth.ac.uk4
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
Fractography Resource - mjames@plymouth.ac.uk5
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
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Fractography Resource - mjames@plymouth.ac.uk6
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
Fractography Resource - mjames@plymouth.ac.uk7
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
Fractography Resource - mjames@plymouth.ac.uk8
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
Fractography Resource - mjames@plymouth.ac.uk9
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
Fractography Resource - mjames@plymouth.ac.uk10
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 60°C – diagram indicates that chloride SCC occurs at this temperature in acid solutions with 104 ppm of chlorides present
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Fractography Resource - mjames@plymouth.ac.uk11
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
Fractography Resource - mjames@plymouth.ac.uk12
Fatigue in polycarbonate
YS = 20 MPa (initial cyclic yield) - annealed state – 2 mm thick plate
R = 0.5
Near the notch root
Fractography Resource - mjames@plymouth.ac.uk13
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
Fractography Resource - mjames@plymouth.ac.uk14
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
Fractography Resource - mjames@plymouth.ac.uk15
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
Fractography Resource - mjames@plymouth.ac.uk16
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
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