MMET 207 Exam 2 - TAMU – Craig
Questions and Answers | Latest Version
| 2024/2025 | Rated A+
What defines a superalloy, and where are they typically used?
✔✔Superalloys are high-performance alloys designed to withstand extreme environments, such
as high temperatures and corrosion. They are commonly used in jet engines and gas turbines due
to their ability to maintain strength and stability at elevated temperatures.
How does phase transformation influence the properties of steel?
✔✔Phase transformation affects steel's mechanical properties by altering its microstructure. For
instance, the transformation from austenite to martensite significantly increases hardness and
strength, making the steel suitable for applications requiring durability.
What is the significance of the eutectoid point in the iron-carbon phase diagram?
✔✔The eutectoid point is crucial as it indicates the composition at which austenite transforms
into pearlite upon cooling. Understanding this transformation helps in controlling the mechanical
properties of steel during heat treatment.
In what way do grain boundaries affect the strength of metallic materials?
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,✔✔Grain boundaries act as barriers to dislocation movement, enhancing the strength of metals
through a phenomenon known as the Hall-Petch relationship. Finer grains typically lead to
stronger materials due to increased grain boundary area.
What are the advantages of using titanium alloys in aerospace applications?
✔✔Titanium alloys offer a high strength-to-weight ratio, excellent corrosion resistance, and the
ability to withstand high temperatures, making them ideal for aerospace components where
performance and weight are critical.
How can fatigue failure be prevented in metallic structures?
✔✔Fatigue failure can be prevented by implementing design modifications, improving surface
finish, applying protective coatings, and using heat treatment processes to enhance the material's
resistance to cyclic loading.
What role do metallurgical tests play in the quality control of metallic materials?
✔✔Metallurgical tests, such as tensile tests and impact tests, are vital for assessing the
mechanical properties and overall quality of materials, ensuring they meet industry standards and
specifications for their intended applications.
Explain the concept of alloying in steel and its impact on performance.
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,✔✔Alloying involves adding elements like chromium, nickel, or molybdenum to steel to
enhance specific properties, such as strength, toughness, and corrosion resistance, leading to
materials tailored for particular applications.
What is the difference between tensile strength and yield strength in metals?
✔✔Tensile strength is the maximum stress a material can withstand while being stretched before
failing, whereas yield strength is the stress at which a material begins to deform plastically,
indicating the transition from elastic to plastic deformation.
How does the process of annealing affect the microstructure of metals?
✔✔Annealing is a heat treatment process that relieves internal stresses, refines grain structure,
and improves ductility by heating the metal and allowing it to cool slowly, making it easier to
work with in subsequent processes.
What is the significance of a material’s elastic limit?
✔✔The elastic limit is the maximum stress that a material can withstand without permanent
deformation. Beyond this limit, the material will not return to its original shape, highlighting its
importance in structural applications.
What techniques are used to improve the corrosion resistance of metallic materials?
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, ✔✔Techniques such as surface coatings, galvanization, and the addition of corrosion-resistant
alloys can enhance the longevity of metallic materials by protecting them from environmental
factors that cause corrosion.
How do welding techniques affect the mechanical properties of metals?
✔✔Welding techniques can significantly alter the mechanical properties of metals by changing
their microstructure in the heat-affected zone, which may lead to variations in hardness,
toughness, and residual stresses.
Cold Work ✔✔O, W, A, D
O series (Cold Work) ✔✔Oil Hardening
O1, O2, O6, O7
W series (Cold Work) ✔✔Water Hardening
W1, W2, W5
A series (Cold Work) ✔✔Medium Alloy Air Hardening
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