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Things I keep getting wrong
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- 1Three basic fracture mechanisms (w/ brief description)Brittle (fracture normal to applied load; unpredictable since it's before yielding; grains have shiny appearance)
Ductile/shear (predictable since after yielding; failure occurs on planes w/ max. shear stress; fibouros appearance)
Intergranular (occurs at elevated temperatures) - 2Explain yieldingTransition from elastic - plastic deformation. Metals have heaps of dislocations. When shear stress along a slip place reaches a critical value, dislocation movement occurs! In polycrystalline metals, this is a gradual process and some grains are orienteed so that this is easier!
- 3How does temperature affect fracture and fracture mechanisms? Explain.At a certain temperature, the fracture mech. changes from shear - brittle (e.g. at 50˚, BCC phase might fail in a predictable shear manner, but at -50˚ it might fail in a brittle manner - unpredictable!)
- 4Supersaturated solid solutionFast cooling doesn't give a second phase time to produce grains!
- 5CoringA change in the chemical composition of all grains. When dendrites are finalising their form, little pockets of liquid remain with a different composition. Slow cooling removes this variation, but fast cooling doesn't.
- 6Homogenisation annealprolonged heating just below the solidus temperature (allows the diffusion of atoms as if it were slow cooling)
- 7How does specimen geometry affect the fracture mechanism? Explain.Notches, cracks & surface irregularities increase stress on the immediate area around the irregularity.
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- Descripción
- MEC1201 Materials Engineering Fichas sobre Things I keep getting wrong, creado por Kyan Clay el 04/05/2016.
- Creado por
- Kyan Clay · may 2016
- Actualizado
- 11 may 2016
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