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Examples of Fractography in Other Materials

Explore different materials through fractography to understand compression and tensile fatigue, stress corrosion cracking in stainless steel, and fatigue behavior in polycarbonate.

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Examples of Fractography in Other Materials

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  1. Examples of Fractography in Other Materials Professor M Neil James mjames@plymouth.ac.uk Department of Mechanical & Marine Engineering University of Plymouth Drake Circus, Plymouth PL4 8AA ENGLAND Fractography Resource - mjames@plymouth.ac.uk

  2. 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.uk

  3. 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.uk

  4. 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.uk

  5. 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 Fractography Resource - mjames@plymouth.ac.uk

  6. 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.uk

  7. 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.uk

  8. 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.uk

  9. 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.uk

  10. 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 Back to Contents Fractography Resource - mjames@plymouth.ac.uk

  11. 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.uk

  12. 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.uk

  13. 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.uk

  14. 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.uk

  15. 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.uk

  16. 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 Fractography Resource - mjames@plymouth.ac.uk

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