Term
| What is a solid solution? |
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Definition
| a type of alloying where the crystal stucture of the solvent is maintained. |
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Term
| What are the two conditions to form a complete substitutional solid solution? |
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Definition
1. the two metals must have a similar crystal structure.
2. the difference in the solvent and solute's atomic radii should be no less than 15%. |
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Term
| What are the two conditions to form an interstitial solid solution? |
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Definition
1. the solvent atom must have more than one valence electron.
2. the atomic radius of the solute atom must be less than 59% of the atomic radius for the solvent atom. |
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Term
| what is ferrite? ( solubility, temp, and structure) |
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Definition
| a solid solution of bcc iron. maximum solid solubility of 0.022% C at temp of 727˚C |
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Term
| ductility and hardness of ferrite, austenite, and cementite? |
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Definition
ferrite- soft, ductile
austenite- ductile at elevated temperatures
cementite- hard, brittle |
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Term
| what is austenite? (solubility, temp, and structure) |
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Definition
a solid solution where iron has undergone a polymorphic transformation from a bcc to an fcc structure.
maximum solid solubility of 2.11% C at 1148˚C. |
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Term
| what is cementite? (definition, solubility) |
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Definition
100% iron carbide, intermetallic compound;
has a carbon content of 6.67 |
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Term
| What are the two mechanisms of strain hardening? |
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Definition
dislocations:
1. become entangled and interfere with each other
2. are impeded by barriers |
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Term
| What are the three steps of annealing? |
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Definition
1. recovery
2. recrystallization
3. grain growth |
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Term
| What is the correlation between degree of deformation and grain size? |
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Definition
inversely related;
the greater the degree of deformation, the smaller the grain becomes. |
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Term
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Definition
| The extent of plastic deformation that the material undergoes before fracture. |
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Term
| Comparing two tensile test graphs, which graph would be the toughest? |
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Definition
| The one with the highest positive slope because the material is becoming tougher as it is strained. |
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Term
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Definition
| the resistance to permanent indentation |
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Term
| What are 4 methods to minimize fatigue failure? |
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Definition
1. inducing compressive residual stresses on surfaces
2. case hardening
3. providing a fine surface finish
4. selecting appropriate materials |
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Term
| What are 4 factors of properties and behaviors of metals and alloys? Which is the most common for property improvement? |
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Definition
1. composition
2. structures
3. processing history
4. heat treatment --> most common |
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Term
| In the structure of an alloy, , if the particular crystal structure of the solvent is maintained during alloying, it is called _________ and if not, it is called ___________. |
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Definition
1.solid solutions
2. intermetallic compounds |
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Term
| What are the two conditions to make a substitutional solid solution? |
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Definition
1. the two metals must have similar crystal structures
2. the difference in the atomic radii should be less than 15% |
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Term
| What are the two conditions to make a interstitial solid solution? |
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Definition
1. the solvent atom must have one or more valence electrons.
2. the radius of the solute atom must be less than 59% of the radius of the solvent atom. |
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Term
| strength and ductility of solid solutions vs. two-phase alloys |
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Definition
| two-phase alloys are stronger and less ductile than solid solutions |
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Term
| Why are two-phase alloys stronger and less ductile than solid solutions? |
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Definition
| in a two-phase alloy system, the blocking of dislocations make it stronger. |
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Term
| What is eutectic temperature? |
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Definition
| The temperature where a liquid solution decomposes into two solid components |
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Term
| In an iron carbide system, how much carbon does pure iron, steel, and cast iron contain? |
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Definition
pure iron- 0.008%
steel- 2.11%
cast iron- 6.67% |
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Term
| Correlation between grain size and strength, ductility, microporosity, and cracks |
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Definition
the smaller the grain size, the stronger, more ductile, less microporosity, and less crack.
inversely--> strength and ductility
directly--> microporosity and crack |
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Term
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Definition
1. formation of an outer chill zone
2. refines grain size
3. accelerates the transition from columnar to equiaxed grains |
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Term
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Definition
| a method of breaking dendrite arms by vibration or agitation in early stages of solidification |
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Term
| 4 methods to eliminate porosity |
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Definition
1. provide adequate liquid metal
2. apply internal or external chills
3. mold materials with higher thermal conductivity
4. subject casting to hot isostatic pressing |
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Term
True or False:
Metal flow rates must be high enough to avoid premature chilling and solidification. |
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Definition
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Term
True or False:
Laminar flow is the most preferable flow in casting. |
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Definition
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Term
True or False:
Flow rate must not be so high as to cause excessive turbulence. |
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Definition
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Term
True or False:
Temperature is the highest at the interface of the mold wall. |
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Definition
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Term
| What type of materials are used in various manufacturing processes? |
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Definition
| ferrous, nonferrous, ceramic, plastic, glass |
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Term
| Describe 5 important manufacturing processes |
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Definition
| forming and shaping, rolling, finishing, casting, machining |
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Term
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Definition
| strain hardening by dislocation |
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Term
| Describe four hardness tests |
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Definition
1. Brinell- involves pressing a steel or tungsten carbide ball 10 mm in diameter onto a surface with a load of 500, 1500, or 3000 kg
2. Rockwell- indenter is pressed onto the surface first with a minor load then a major load
3. Knoop- uses a pyramid shaped indenter with a load that ranges from 25 g to 5 kg
4. Vickers- uses a diamond shaped indenter with a load that ranges from 1 to 120 kg |
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Term
| What is the fatigue failure of engineering material? |
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Definition
| residual tensile stress causes cracks to grow and propogate through the material until a critical crack length is reached. |
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Term
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Definition
| the failure mode of engineering material by grain boundary sliding at elevated temperatures. |
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Term
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Definition
| where austenite has been transformed into ferrite and cementite (because of extra C, cementite is formed) |
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Term
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Definition
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Term
| Describe about martensite (cooling, structural change, material property) |
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Definition
| *austensite is cooled at a high rate and transforms from fcc to body-centered tetragonal; It's hard, brittle, and lacks toughness |
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Term
| Is tempering necessary following heat treatment of martensite? why? |
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Definition
| yes. quenching may cause distortions or cracking. tempering is necessary to improve toughness |
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Term
| What is a disadvantage of open die forging? |
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Definition
| barreling by friction forces |
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Term
| What are two advantages of open die forging? |
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Definition
| simple and inexpensive and has good strength and toughness |
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Term
| Why do forged parts have good strength and toughness? |
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Definition
| The metal flow in the die and grain structures can be controlled. |
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Term
| What is impression die forging? |
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Definition
| workpiece takes the shape of the die cavity in two dies; material flows outward and flash is formed, which prevents the outward flow. |
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Term
| What is the root cause of internal defects? |
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Definition
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Term
| Which extrusion process produces the maximum deformation? |
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Definition
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Term
| What are the two most important design factors for higher quality extrusion? |
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Definition
1. minimum sharp corners
2. uniform section thickness |
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Term
| What causes the pipe defect? |
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Definition
1. increased die angle
2. higher friction between billet and chamber |
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Term
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Definition
| draw surface oxides and impurities toward the center of the billet |
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Term
| The tendency toward Chevron cracking increases if...? |
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Definition
| if the two plastic zones do not meet each other, |
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Term
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Definition
| workpiece is rotated and a layer is removed as cutting tool moves to the left. |
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Term
| What is cutting-off operation? |
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Definition
| cutting tool moves radially inward and separates the right side from the bulk of the blank. |
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Term
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Definition
| rotating cutting tool removes a layer of material from the surface of workpiece |
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Term
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Definition
| a rotating cutting tool travels along a certain depth in the workpiece and produces a cavity |
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Term
| What factors influence machining operations? (11) |
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Definition
| Cutting speed, depth of cut, feed, cutting fluids, tool angles, continuous chip, built-up edge chip, discontinuous chip, temperature rise, tool wear, and machinability |
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Term
| What describes continuous chip? |
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Definition
| good surface finish, steady cutting forces, undesirable in automation |
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Term
| What are the dependent variables of the mechanics of cutting? (5) |
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Definition
| type of chip produces, force and energy dissipated during cutting, temperature rise in the workpiece, tool, and chips, tool wear and failure, and surface finish and surface integrity of the workpiece |
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Term
| What are independent variables of cutting? (12) |
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Definition
| Tool material and coatings, tool shape, surface finish, and sharpness, workpiece material and condition, cutting speed, feed, and depth of cut, cutting fluids, characteristics of the machine tool, workholding and fixturing. |
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Term
| As the rake angle decreases and/or the friction at the tool-chip interface (rake face) increases, (4) |
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Definition
1. the shear angle decreases
2. chip becomes thicker
3. more energy dissipation (higher strain)
4. temperature rises |
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Term
| What is group technology? |
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Definition
| a manufacturing philosophy to take advantage of similarities in design and production |
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Term
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Definition
1. Visual inspection
2. Parts classification and coding
3. production flow analysis |
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Term
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Definition
1. promotes standardization of tooling, fixturing, and setups
2. material handling is reduced
3. process planning and production scheduling are simplified
4. setup times are reduced
5. work-in-process is reduced
6. worker satisfaction usually improves by collaboration
7. higher quality work is accomplished |
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Term
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Definition
| shrinkage, entrained or dissolved gas |
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Term
| What characteristics of molten metal influence fluidity? |
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Definition
| viscosity, surface tension, inclusions, solidification patter of the alloy, mold design, mold material and its surface characteristics, degree of superheat, rate of pouring, and heat transfer |
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Term
| How can you make two-phase alloys stronger? |
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Definition
| alloying with finely dispersed particles |
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Term
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Definition
1. Data Collection
2. sortation of process routings
3. PFA chart
4. Cluster analysis |
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Term
| Prevention of chevron defect: |
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Definition
| decrease die angle and increasing the reduction area |
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