Term
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Definition
| An element in the periodic table, good conductor of heat and electricity |
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Term
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Definition
| Metallic solid solution of 2+ elements |
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Term
(Processing terminology for metals and alloys)
High Temperature creep? |
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Definition
| is the slow stretching of steel under stress at high temperatures |
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Term
(Processing terminology for Metals/alloys)
Adhesion |
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Definition
| the sticking together of two unlike metals involving a mechanical bond. |
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Term
(Processing terminology for Metals/alloys)
Annealing
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Definition
| Is the softening of a metal and removing of brittleness |
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Term
(Processing terminology for Metals/alloys)
Tempering |
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Definition
| Is obtaining the desired hardness and toughness in metal |
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Term
(Processing terminology for Metals/alloys)
Hardness |
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Definition
| is the ability of a material to withstand indentation |
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Term
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Definition
| is the capability of a material to be shaped or formed under pressure or by hammer. |
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Term
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Definition
| ability of a material to resist being pulled apart |
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Term
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Definition
| ability of a material to resist deformation when placed under compressive forces |
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Term
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Definition
| The ability of a material to resist forces acting in opposing directions. |
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Term
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Definition
| The ability of a material to take repeated loads without deforming |
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Term
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Definition
| The ability of a material to resist shock |
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Term
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Definition
| The ability of a material to bend without deforming or breaking |
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Term
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Definition
| is the way molecules of a substance are arranged or how they are packed or fitted together |
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Term
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Definition
| is the name given to the patterns of atoms within a crystal structure |
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Term
| Common Crystal Structures |
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Definition
BCC-(body centered cubic) has 9 atoms and usually have a high strength and are difficult to work when cold
FCC-(face centered cubic) has 14 atoms and usually means the material is plastic and malleable
HCP-(Close-packed hexagon) has 17 atoms and the material is usually non-plastic and must be heated in order to be worked. |
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Term
| Iron-Carbon phase diagram |
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Definition
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Term
| Types of metal in Iron-Carbon phase diagram |
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Definition
Austenite- is a FCC structure with an atom in each corner and one in the center
Ferrite- is a BCC structure and has atoms in each corner and also one in the center of each face.
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Term
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Definition
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Term
| how are strength properties measured? |
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Definition
| by doing a tensile test where the load versus the displaement is measured and then converted into a stress versus strain relationship. |
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Term
| what are the major regions on a stress-strain graph? |
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Definition
| elastic region where everything done to the material is reversible, plastic region where deformation occurs. and finally the fracture stress region where the material looses all strength and fails. |
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Term
| how can the yeild stress/proof stress be increased? |
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Definition
| it can be increased by controlling the movement of dislocations within the material. |
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Term
| what is a proportional and elastic limit? |
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Definition
| the proportional limit is the stress level below which stress is proportional to strain. and the elastic limit is where the stress level is below where the deformation strains are fully reversible |
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Term
| what is the yeild strength? |
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Definition
| the yeild strength is the stress level at which irreversible plastic deformation starts |
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Term
| what is slip and how does it occur? |
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Definition
at the yeild stress σy the atom planes within a material can slide over each other irreversibly. This happens when the shear stress τy reaches a critical value relating to (σy=/≈2xτy)
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Term
| what happens when slip occurs? |
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Definition
| the original bonds between atoms are broken and are then reformed with new neighbours |
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Term
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Definition
| The amount of slip planes depends entirely on the crystaline structure. and slip its self depends on the lattice structure. when slip occurs two things remain constant and that is the spacing between planes as well as the number of planes in the specimen |
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Term
| how do you calculate theroretical yeild strength? |
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Definition
| by using the equation σy(approx)/=E/8 however for metals and alloys this usually isnt the case beause of imperfections within the material. or if it is not possible to slip complete planes simultaneously |
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Term
| what are the properties of a dislocation? |
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Definition
| dislocation movement causes plastic deformation the types of disloation that can occur are edge, screw or mixed. |
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Term
| how can disloation movement be reduced? and how can this be achieved? |
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Definition
| dislocation movement can be reduced by hardening, which can be achieved using grain refinement, solid solution hardening, precipitaion hardening or work (strain) hardening. |
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Term
| what is the hall-petch equation? |
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Definition
| the hall-petch equation is: (yeild stress)σy=σ0+Kyd(-1/2) and σ0 and Ky are both constants. also for bigger grain sizes less force is needed to move a dislocation. |
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Term
| what is Solid Solution Hardening? and what types are there? |
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Definition
| the main principle of this is to add impurities to form a solid solution aka an alloy. there are two types, one being interstitial solid solution and the other being substitutional solid solution. the first uses bigger atoms that the parent element (eg. brass where zinc is added to copper) as zinc has bigger atoms it makes it harder for planes to slip. whereas the second uses smaller atoms (e.g steel where carbon is added to iron) to disrupt planes. |
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