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Questions and Answers
Which of these properties describes a material's ability to be easily deformed without breaking?
Which of these properties describes a material's ability to be easily deformed without breaking?
What is the purpose of 'killed' steel?
What is the purpose of 'killed' steel?
What does the Izod test measure?
What does the Izod test measure?
Which of the following characteristics is NOT a mechanical property?
Which of the following characteristics is NOT a mechanical property?
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What does the term 'isotropic' mean in the context of materials?
What does the term 'isotropic' mean in the context of materials?
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Which of the following properties is most directly related to a material's ability to be cut or machined?
Which of the following properties is most directly related to a material's ability to be cut or machined?
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Which property is defined as the percentage change in length of a tensile specimen at the point of fracture?
Which property is defined as the percentage change in length of a tensile specimen at the point of fracture?
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Based on the provided information, what is the difference between a 'killed' steel and a 'rimmed' steel?
Based on the provided information, what is the difference between a 'killed' steel and a 'rimmed' steel?
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What process is used to deform a metal plastically at a temperature below its recrystallization temperature, resulting in increased strength and machinability?
What process is used to deform a metal plastically at a temperature below its recrystallization temperature, resulting in increased strength and machinability?
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What property describes a material's ability to absorb or damp vibrations by converting kinetic energy into heat?
What property describes a material's ability to absorb or damp vibrations by converting kinetic energy into heat?
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Which of the following is NOT a consequence of age hardening?
Which of the following is NOT a consequence of age hardening?
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Which term describes the tendency of a material to fracture without significant deformation?
Which term describes the tendency of a material to fracture without significant deformation?
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What is the primary purpose of alloying elements in steel?
What is the primary purpose of alloying elements in steel?
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What characteristic describes a material exhibiting different properties when tested in different directions?
What characteristic describes a material exhibiting different properties when tested in different directions?
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What test measures the impact strength of a material by assessing the energy absorbed in breaking a specimen?
What test measures the impact strength of a material by assessing the energy absorbed in breaking a specimen?
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Which of the following defines brittleness at low temperatures?
Which of the following defines brittleness at low temperatures?
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What is the definition of proof stress?
What is the definition of proof stress?
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What is the purpose of solution heat treatment?
What is the purpose of solution heat treatment?
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What is the relationship between stiffness and modulus of elasticity?
What is the relationship between stiffness and modulus of elasticity?
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What is the effect of strain hardening on a material?
What is the effect of strain hardening on a material?
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Which of the following correctly describes rimmed steel?
Which of the following correctly describes rimmed steel?
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What is the definition of transverse strength?
What is the definition of transverse strength?
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Which of the following correctly describes relaxation stresses?
Which of the following correctly describes relaxation stresses?
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How does precipitation heat treatment affect the properties of an alloy?
How does precipitation heat treatment affect the properties of an alloy?
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What is the primary purpose of carburizing steel?
What is the primary purpose of carburizing steel?
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Which of these is NOT a common method of carburizing?
Which of these is NOT a common method of carburizing?
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What is the approximate maximum case depth achievable with liquid carburizing?
What is the approximate maximum case depth achievable with liquid carburizing?
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A square bar is to be used as a cantilever beam. What is the key material property you would use to calculate the required cross-sectional area to support a given load?
A square bar is to be used as a cantilever beam. What is the key material property you would use to calculate the required cross-sectional area to support a given load?
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What is the approximate working stress on a steel tapered pin securing a lever to a shaft, if the pin has a diameter of 10 mm and experiences a pull of 200 Newtons at a radius of 800 mm?
What is the approximate working stress on a steel tapered pin securing a lever to a shaft, if the pin has a diameter of 10 mm and experiences a pull of 200 Newtons at a radius of 800 mm?
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Which of these options is a common carburizing gas?
Which of these options is a common carburizing gas?
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A round steel bar with a yield strength of 300 MPa is to be subjected to a direct tension of 200 kN. What is the minimum required diameter of the bar to avoid yielding?
A round steel bar with a yield strength of 300 MPa is to be subjected to a direct tension of 200 kN. What is the minimum required diameter of the bar to avoid yielding?
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A steel tapered pin securing a lever to a shaft experiences a pull of 50 pounds at a 30-inch radius. What is the primary factor affecting the stress on the pin, assuming everything else remains constant?
A steel tapered pin securing a lever to a shaft experiences a pull of 50 pounds at a 30-inch radius. What is the primary factor affecting the stress on the pin, assuming everything else remains constant?
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Which of the following alloys is non-magnetic at room temperature?
Which of the following alloys is non-magnetic at room temperature?
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Which alloy is specifically designed for use in watch and instrument springs?
Which alloy is specifically designed for use in watch and instrument springs?
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What is the maximum safe torsional stress for Elgiloy?
What is the maximum safe torsional stress for Elgiloy?
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What is the typical hardness range for Elinvar after precipitation hardening?
What is the typical hardness range for Elinvar after precipitation hardening?
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Which material is commonly used for stationary guy ropes?
Which material is commonly used for stationary guy ropes?
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Which alloy is known for its resistance to corrosion and suitability for sub-zero temperatures?
Which alloy is known for its resistance to corrosion and suitability for sub-zero temperatures?
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What is the approximate maximum operational temperature for Elinvar, assuming torsional stress is kept within safe limits?
What is the approximate maximum operational temperature for Elinvar, assuming torsional stress is kept within safe limits?
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Which of the following materials is NOT specifically mentioned as being used in watch or instrument springs?
Which of the following materials is NOT specifically mentioned as being used in watch or instrument springs?
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Which of these processes involves transforming combined carbon into temper carbon?
Which of these processes involves transforming combined carbon into temper carbon?
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What is the primary purpose of normalizing?
What is the primary purpose of normalizing?
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What is the difference between work hardening and strain hardening?
What is the difference between work hardening and strain hardening?
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Which of the following is NOT a typical consequence of annealing?
Which of the following is NOT a typical consequence of annealing?
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Which statement is TRUE about the transformation range for ferrous alloys?
Which statement is TRUE about the transformation range for ferrous alloys?
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Which process is MOST LIKELY to be used for improving the machinability of cast iron?
Which process is MOST LIKELY to be used for improving the machinability of cast iron?
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Which heat treatment process involves heating above the transformation range followed by quenching?
Which heat treatment process involves heating above the transformation range followed by quenching?
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What is the primary purpose of heat treatment?
What is the primary purpose of heat treatment?
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Study Notes
Summary of Machine Design and Shop Practice
- Offset: Usually 0.2% (0.002 in./in. of strain) for steel, aluminum, and magnesium alloys.
- Stress (s): Measured in pounds or kips per square inch (psi or ksi). A kip equals 1000 lb.
- Strain: Represents the deformation per unit gage length (in. per in).
- Ultimate Stress/Tensile Strength: The maximum load divided by the original area before straining. Located at the highest point on the stress-strain curve.
- Elastic Limit: Maximum stress a specimen can withstand without permanent deformation.
- Proportional Limit: Where the stress-strain curve deviates from a straight line.
- Modulus of Elasticity (E): A proportionality constant in tension, representing the slope of the straight part of the stress-strain curve; a measure of stiffness.
- Yield Point (YP): Stress at which a low or medium carbon steel undergoes a marked elongation without an increase in load.
- Yield Strength: Stress for a specified deviation from the straight part of the stress-strain curve.
- Factor of Safety (N): A number dividing the criterion of strength, to determine a design criterion (sometimes called 'factor of ignorance').
- Computed/Nominal Stress: Stress calculated from a stress equation.
Summary of Age Hardening/Precipitation Hardening
- Age Hardening: Occurs in some metals (stainless steel, aluminum, copper); after solution heat treatment at ambient temperature. The process involves constituent precipitation from a solid solution.
- Consequences: Increased strength and hardness, decreased ductility. Accelerated at moderately elevated temperatures. Artificially induced.
- Alloy: Substance with metallic properties from at least one metal.
- Alloying Elements: Metallic elements added to steel to adjust properties.
Summary of Charpy Test
- Charpy Test: Specimen, supported at both ends, is broken by a falling pendulum.
- Measurement: Energy absorbed in breaking specimen
- Significance: Measure of material's impact strength.
Summary of Cold Shortness
- Cold Shortness: Brittleness of metals at ordinary or low temperatures.
- Metal Deformation Temperatures: Cold working occurs below the recrystallization temperature.
Other Material Properties
- Elasticity: Ability to return to original shape after deformation. Stress is proportional to strain during elastic deformation.
- Embrittlement: Loss of ductility due to physical or chemical change
- Ductility: Property that permits permanent deformation before fraction; percentage elongation and percentage reduction of area are indices.
- Brittleness: Tendency to fracture without appreciable deformation; opposite of ductility.
- Homogeneity: Material having the same structure throughout; steel is composed of randomly oriented iron crystals of different sizes with other matter.
- Isotropy: Material having the same properties in all directions; wood has grain, rolled steel isn't isotropic.
Summary of Other Important Concepts
- Decarburization: Loss of carbon from steel surface during heat treatments.
- Case Hardening: Significantly hardens the surface (case) of an iron alloy, while the core remains softer.
- Carburizing: Process to add carbon to the surface of steel. Typically with hot carbonaceous solids, liquids or gasses above the transformation temperature.
- Pack/Box Carburizing and Gas Carburizing: Common Carburizing methods.
- Liquid Carburizing: Part is immersed in molten salt bath
- Relaxation Stresses: Stresses not directly from loads or temperature gradients; due to factors like unequal cooling rates.
- Hardening: Heating of steels beyond the transformation range, then quenching, to increase hardness
- Toughness: Ability to withstand shock load without breaking
- Stiffness: Resistance to deformation; Measured by modulus of elasticity in elastic range. Higher modulus, higher stiffness.
Summary of Mechanical Testing
- Transverse Strength: Results of a transverse bend test. The specimen is mounted as a simple beam. Also referred to as rupture modulus.
- Critical Range/Transformation Range: Temperature interval where austenite is formed or disappears during heating or cooling.
- Hardening of a Material: Measured by resistance of a material to indentation.
- Brinell Hardness Number (BHN): Load in kilograms divided by the area of the surface of the indentation in square millimetres.
- Hardenability: Capacity of steel to become hard after being cooled from above its transformation range.
- Stress Relieving: Heating to suitable temperature just below transformation range, holding for a period and slowly cooling to reduce internal residual stress.
- Tempering: Reheating hardened or normalized steel to a temperature below the transformation range.
- Normalizing: Heating to about 100°F above transformation range and slowly cooling to below that range in still air. Used to produce a uniform structure..
- Spheroidizing: Prolonged heating at a temperature slightly below transformation range, often followed by slow cooling. Produces a rounded shape of carbides.
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Description
This quiz focuses on key concepts in machine design and shop practices, such as stress, strain, and yield strength. Understand the important parameters like modulus of elasticity and ultimate tensile strength essential for materials engineering. Test your knowledge on these critical elements of mechanical design.
