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MatSE 259 Exam 1 Review Session: Exam Structure, Steel Designation, Alloy Designation, Mechanical Properties, Phase Diag

This review session covers the exam structure, steel and alloy designation systems, mechanical properties, phase diagrams, and dislocations in materials science and engineering. Topics include tensile testing, hardness testing, impact fracture testing, creep testing, fatigue testing, crystal structures, and interactions of dislocations.

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MatSE 259 Exam 1 Review Session: Exam Structure, Steel Designation, Alloy Designation, Mechanical Properties, Phase Diag

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  1. MatSE 259 Exam 1 Review Session • Exam structure – 25 questions, 1 mark each • Do NOT forget to write your student I.D. on the answer sheet • Exams are sent to UTS for machine grading – please mark your answers clearly. No credit will be given if the machine cannot decipher your score

  2. Steel designation • AISI-SAE numbering system for steels • XX XX Percent carbon (wt) x 100 Alloy content For example, 5060 has ???

  3. Number Major alloy addition 1xxx - 2xxx Cu 3xxx Mn 4xxx Si 5xxx Mg 6xxx Mg & Si 7xxx Zn 8xxx other Aluminium alloy designation • Numbering system for Al alloys not the same as steels Numbering system also includes heat treatments – see website

  4. Mechanical Properties Change due to; • C content in steel • Alloying elements • Heat treatment - annealing, normalizing, tempering… • Mechanical working - cold rolling, hot rolling, STRUCTURE changes

  5. Phase Diagrams Differentiate between “phase” and “state” Phase diagram is a plot showing the relationship between temperature, composition and the quantities of phases in a system. On a phase diagram, you should be able to understand simple heat treatments, like the T4 studied in class. For example, Al 2024-T6.

  6. Mechanical properties • Tensile testing • Elastic deformation – Plastic deformation – Yield • Hooke’s Law • Hardness testing • Penetration by indenter under load • Types – Rockwell, Brinell, Vickers, Knoop, Mohs • Hardness-strength conversion

  7. Mechanical properties (contd.) • Impact Fracture testing • Charpy and Izod • Ductile-to-brittle transition • Creep testing • Primary, secondary, tertiary • Steady-state creep rate • Fatigue testing • S-N curves • Fatigue limit, fatigue strength, fatigue life • Investigation of the fracture surface for the origin of crack • “Chevron’’, striations, beachmarks

  8. Dislocations • Dislocations move along slip planes – ductility • It is possible to plastically deform a material which contains dislocations

  9. Crystal Structures • Most common crystal structures for metals are: • Cubic close-packed • Hexagonal close-packed • Body centered cubic • close-packed; most densely packed • Slip planes are the most densely packed planes in these structures.

  10. Dislocations • The ability of a metal to deform depends on the ability of the dislocation to move • Restricting dislocation motion will strengthen the material; • - solid solution hardening • - grain size reduction • - strain hardening (work hardening) • - precipitation hardening (age hardening)

  11. Dislocations Interactions • With each other • - annihilate • - entangle • - form generators • With grain boundaries • - disappear • - pile-ups

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