1.
As hot working progresses, the energy required for further processing (assuming the temperature of the part is held constant):
Correct Answer
D. Any one of the above may be true, depending on material.
Explanation
The energy required for further processing in hot working can vary depending on the material being worked on. Some materials may require more energy as the process progresses, while others may require less or the energy requirement may remain constant. Therefore, any of the given options could be true depending on the specific material being used.
2.
A fatigue crack is a service defect that is caused by a:
Correct Answer
B. Cyclic loading of the part below the yield strength of the material.
Explanation
A fatigue crack is caused by cyclic loading of the part below the yield strength of the material. When a material is subjected to repeated loading and unloading, stresses are generated within the material. If these stresses are below the yield strength of the material, they can cause the formation and propagation of cracks over time. This is known as fatigue failure. Cyclic loading above the yield strength can cause plastic deformation and yield, but it is not the main cause of fatigue cracks. Local overheating and corrosive atmosphere can lead to other types of damage, but they are not specifically related to fatigue cracks.
3.
The middle portion of a molding flask is called a:
Correct Answer
C. Cheek
Explanation
The middle portion of a molding flask is called a cheek. The cheek is the section of the flask that separates the cope (top) and drag (bottom) portions. It provides support and stability to the mold during the casting process. The cheek is typically made of a sturdy material such as metal or wood to withstand the pressure and heat of the molten metal.
4.
A cause of gas porosity in welds is:
Correct Answer
B. Improper cleaning or preheating
Explanation
Improper cleaning or preheating can cause gas porosity in welds. When the surface of the material is not properly cleaned before welding, contaminants such as dirt, oil, or rust can be trapped in the weld, leading to the formation of gas pockets. Additionally, if the material is not preheated to the correct temperature, moisture or other volatile substances may vaporize and create gas bubbles during the welding process. These gas bubbles can weaken the weld and result in porosity. Therefore, proper cleaning and preheating are crucial to prevent gas porosity in welds.
5.
In the resistance welding process:
Correct Answer
B. The pieces to be joined are held firmly together under pressure, followed by the generation of heat at the interface.
Explanation
In the resistance welding process, the correct answer states that the pieces to be joined are held firmly together under pressure, followed by the generation of heat at the interface. This is the accurate explanation of the resistance welding process. The pressure applied helps to ensure that the pieces are securely held together, and the generation of heat at the interface allows for the welding of the two parts. This process does not involve melting the parts or adding a filler metal, but rather relies on the application of pressure and heat to create a strong weld.
6.
In a mold, the runner connects:
Correct Answer
C. The sprue to the ingate
Explanation
The sprue is the channel through which the molten material flows from the pouring basin into the mold cavity. The ingate, on the other hand, is the entry point of the molten material into the mold cavity from the sprue. Therefore, it is logical for the sprue to be connected to the ingate in order to facilitate the flow of material into the mold cavity.
7.
Metal forming such as rolling, results in:
Correct Answer
A. Plastic flow of the metal
Explanation
Rolling involves applying compressive forces to deform metal, causing it to undergo plastic deformation. This plastic flow allows the metal to change shape without fracturing, resulting in desired changes in thickness, length, or shape.
8.
A welding defect that occurs at the root and runs parallel with the weld is:
Correct Answer
D. Lack of penetration
Explanation
Lack of penetration refers to a welding defect where the weld does not fully penetrate the base metal, resulting in an incomplete bond. This defect occurs at the root of the weld and runs parallel to it. It can weaken the joint and compromise its structural integrity.
9.
Hot working an ingot may produce a product which has:
Correct Answer
D. Any of the above may be correct depending on the circumstances.
Explanation
Hot working an ingot involves subjecting it to high temperatures and mechanical deformation, such as rolling or forging, to shape it into a desired product. The process of hot working can lead to changes in the microstructure of the material, which may result in the formation of new defects or the elimination of existing defects. Therefore, depending on the specific circumstances, hot working can either reduce the number of defects in the original ingot, introduce more defects, or maintain the same number of defects in the final product.
10.
A disadvantage of dry sand molds when compared to green sand molds is:
Correct Answer
A. Erosion of the mold is more common
Explanation
Dry sand molds are made from a mixture of sand and binders, which do not contain moisture. This lack of moisture makes the mold more prone to erosion when compared to green sand molds, which have a higher moisture content. Erosion can occur due to the high temperatures and pressures involved in the casting process, causing the mold to break down and deteriorate more easily. This can lead to a shorter lifespan for the mold and potentially affect the quality and integrity of the casting.
11.
A long defect, parallel to the longitudinal axis of a bar and caused by blowholes, cracks or tears introduced in earlier processing and elongated in the direction of rolling or forging is called:
Correct Answer
A. A seam
Explanation
A seam is a long defect that runs parallel to the longitudinal axis of a bar. It is caused by blowholes, cracks, or tears that were introduced in earlier processing and then elongated in the direction of rolling or forging.
12.
Rapid oxidation of metal surfaces during hot working of a mild steel may;
Correct Answer
D. Adversely affect the application of some non-destructive test
Explanation
During hot working of mild steel, rapid oxidation of metal surfaces can create a layer of oxide on the surface. This oxide layer can interfere with the application of certain non-destructive tests, such as visual inspection or ultrasonic testing, as it can obscure or distort the results. Therefore, the rapid oxidation can adversely affect the application of some non-destructive tests.
13.
An advantage of shell molding over green sand molding is:
Correct Answer
C. Better surface finish is obtainable
Explanation
Shell molding offers better surface finish compared to green sand molding. This is because the shell mold process involves using a resin-coated mold, which creates a smoother and more precise surface on the casting. Green sand molding, on the other hand, uses a mixture of sand, clay, and water, which can result in a rougher surface finish. Therefore, the advantage of shell molding over green sand molding is that it allows for a better surface finish on the castings.
14.
A burst is _____________ discontinuity.
Correct Answer
B. A processing
Explanation
A burst is a processing discontinuity.
15.
Bursts usually have the following characteristics:
Correct Answer
D. Are three dimensional discontinuities having smooth internal surfaces and generally located close to the surface of the wrought material
Explanation
Bursts are described as three-dimensional discontinuities with smooth internal surfaces that are typically situated near the surface of the wrought material. They appear as smooth indentations on metal surfaces and are cavities of varying sizes, usually parallel to the grain. Bursts are extremely thin and flat, aligning parallel to the work surface of the material.
16.
In a rolling mill, flattening and elongation of metal is accomplished by:
Correct Answer
C. Primarily compressive stresses
Explanation
In a rolling mill, flattening and elongation of metal is primarily accomplished by applying compressive stresses. This is because the metal is passed through a series of rollers that exert pressure on it, causing it to deform and elongate. The compressive stresses help to reduce the thickness of the metal and increase its length. Tensile stresses, bending stresses, and high frequency cyclical loads may also play a role in the process, but the primary mechanism for flattening and elongation is the application of compressive stresses.
17.
The fuel gas most commonly used in gas welding is:
Correct Answer
C. Acetylene
Explanation
Acetylene is the most commonly used fuel gas in gas welding because of its high heat output and versatility. It has a high flame temperature, allowing for efficient welding and cutting. Acetylene is also easily controllable, making it suitable for various types of welding applications. Additionally, it can be used with different types of metals and alloys, making it a versatile choice for gas welding.
18.
Cold shuts are most likely to be found in:
Correct Answer
C. Castings
Explanation
Cold shuts are most likely to be found in castings. A cold shut occurs when two portions of molten metal do not properly fuse together during the solidification process. This can happen when there is insufficient heat or fluidity in the metal, causing a lack of fusion between the two sections. Castings involve pouring molten metal into a mold, and if the metal does not properly fuse during solidification, cold shuts can occur. Cold shuts are less common in extrusions, forgings, and sintered parts, making castings the most likely option.
19.
Aircraft turbine blades are usually processed by:
Correct Answer
A. Investment casting
Explanation
Investment casting is the most suitable method for processing aircraft turbine blades because it allows for the production of complex shapes with high dimensional accuracy and a smooth surface finish. This process involves creating a wax pattern of the desired blade shape, which is then coated with a ceramic material. The ceramic shell is heated to remove the wax, leaving behind a hollow mold. Molten metal is then poured into the mold, filling the cavity and solidifying to form the turbine blade. This method ensures the blades have the necessary strength, durability, and aerodynamic efficiency required for their function in an aircraft engine.
20.
The electrodes used for spot welding are usually made of:
Correct Answer
D. Copper
Explanation
Copper is the preferred material for electrodes used in spot welding due to its high electrical conductivity and thermal conductivity. These properties allow for efficient transfer of electrical energy and effective dissipation of heat during the welding process. Copper electrodes also have good resistance to wear and deformation, ensuring longer electrode life and consistent weld quality. Additionally, copper does not contaminate the weld, making it suitable for welding a wide range of materials.
21.
A metal forming operation which allows three dimensional control over the shape of the product is:
Correct Answer
C. Forging
Explanation
Forging is a metal forming operation that allows three-dimensional control over the shape of the product. It involves heating the metal and then applying compressive forces to shape it into the desired form. This process allows for precise control over the dimensions and contours of the final product, making it an ideal choice when three-dimensional control is required. Rolling and extruding are also metal forming operations, but they do not offer the same level of control over the shape as forging does.
22.
A forming operation which results in the greatest dimensional accuracy is:
Correct Answer
D. Forging
Explanation
Forging is the correct answer because it is a forming operation that involves shaping the material by applying compressive forces. The process of forging involves heating the material and then applying pressure to shape it into the desired form. This method allows for precise control over the dimensions and results in a high level of dimensional accuracy. Cold rolling of sheet, hot rolling of sheet, and cold rolling of bars may also result in dimensional accuracy, but forging is known to provide the greatest level of accuracy.
23.
In which of the following joining methods will flaws, when they do occur, be essentially two dimensional?
Correct Answer
D. Brazing
Explanation
Brazing is a joining method where flaws, when they occur, are essentially two-dimensional. In brazing, a filler metal is melted and flowed into the joint, creating a strong bond between the base metals. The filler metal has a lower melting point than the base metals, allowing it to flow and fill the joint. Flaws in brazing typically occur in the form of surface defects, such as cracks or voids, which are two-dimensional in nature. This is in contrast to the other joining methods mentioned, such as gas tungsten arc welding, gas metal arc welding, and submerged arc welding, where flaws can occur in three dimensions.
24.
A flaw which can resemble a cold shut is:
Correct Answer
D. A forging lap
Explanation
A forging lap is a flaw that can resemble a cold shut. A forging lap occurs when a portion of the metal folds over itself during the forging process, creating a defect in the material. This defect can resemble a cold shut, which is a type of discontinuity in a weld where the molten metal does not properly fuse together. Both a forging lap and a cold shut can result in weak points in the material, compromising its structural integrity.
25.
Elements may be added to the filler metal to:
Correct Answer
D. Any of the above
Explanation
The correct answer is "Any of the above." This means that elements may be added to the filler metal for various reasons, including controlling grain growth, increasing ductility, or ensuring adequate corrosion resistance. In other words, the addition of elements to the filler metal can serve multiple purposes and can be done for any of these reasons.
26.
One of the main causes of cold shuts is:
Correct Answer
B. The presence of several sprues or gates in the mold
Explanation
The presence of several sprues or gates in the mold can be one of the main causes of cold shuts. When there are multiple sprues or gates in the mold, it can lead to uneven filling of the molten metal, causing the metal to solidify before it completely fills the mold cavity. This results in incomplete fusion of the metal, leading to cold shuts. Cold shuts are defects where two streams of molten metal fail to fuse together properly, resulting in a visible line or seam in the final product.
27.
An EDM notch formed in 304 stainless steel may cause:
Correct Answer
C. An increase in conductivity
Explanation
When an EDM (Electrical Discharge Machining) notch is formed in 304 stainless steel, it may cause an increase in conductivity. This is because the EDM process involves the use of high-frequency electrical discharges to erode the material, creating small craters or notches. These notches can disrupt the regular structure of the material, creating more pathways for electrical current to flow through. As a result, the conductivity of the stainless steel increases. However, it is important to note that the other options mentioned in the question, such as a local increase in permeability or the formation of austenite around the notch, are not necessarily caused by the EDM process in 304 stainless steel.
28.
Which discontinuity is not normally found in a casting?
Correct Answer
D. Slugging
Explanation
Slugging is not normally found in a casting. Misrun refers to a defect where the molten metal does not completely fill the mold cavity. Porosity refers to the presence of small voids or gas pockets in the casting. Shrinkage is a defect caused by the solidification and cooling of the metal, resulting in a reduction in size. However, slugging is not a common discontinuity in castings and is not typically associated with casting defects.
29.
Non-metallic impurities trapped within the molten metal of a casting are generally called:
Correct Answer
B. Inclusions
Explanation
Inclusions are non-metallic impurities that are commonly found trapped within the molten metal of a casting. These impurities can include various substances such as oxides, slag, or other foreign materials. Inclusions can negatively affect the mechanical properties and overall quality of the casting, leading to potential defects or weaknesses. Therefore, it is important to minimize the presence of inclusions during the casting process to ensure a high-quality final product.
30.
Most manufacturing defects in a tube are:
Correct Answer
A. Axial in direction
Explanation
Most manufacturing defects in a tube are axial in direction. This means that the defects occur along the length of the tube, parallel to its axis. Axial defects can include cracks, splits, or deformations that run along the tube's length. These defects are typically caused by issues during the manufacturing process, such as improper heat treatment or insufficient material quality control. Axial defects can have a significant impact on the structural integrity and performance of the tube, making them a critical concern in manufacturing and quality control processes.
31.
Increasing test sample temperature normally:
Correct Answer
A. Increases electrical resistivity
Explanation
Increasing the test sample temperature normally increases the electrical resistivity. This is because as the temperature increases, the atoms in the material gain more thermal energy and vibrate more vigorously, disrupting the flow of electrons. This increased atomic movement hinders the movement of charge carriers, causing an increase in resistivity.
32.
When thick and thin casting sections are adjacent to each other, what discontinuity may result?
Correct Answer
C. Shrinkage
Explanation
When thick and thin casting sections are adjacent to each other, a potential discontinuity that may result is shrinkage. Shrinkage occurs when there is a difference in cooling rates between the thick and thin sections, causing the metal to contract at different rates. This can lead to internal voids or defects in the casting, compromising its structural integrity. Shrinkage is a common issue in casting processes and needs to be carefully managed to ensure high-quality castings.
33.
Heat exchanger tubes are defect prone at regions:
Correct Answer
D. All of the above
Explanation
Heat exchanger tubes are prone to defects in regions adjacent to support plates, under support plates, and in between support plates. Support plates are used to hold the tubes in place, and due to the stress and pressure exerted on the tubes in these areas, they are more likely to develop defects. This can include cracks, leaks, or corrosion. Therefore, all of the mentioned regions are susceptible to defects in heat exchanger tubes.
34.
Which of the following discontinuities is not normally associated with a casting?
Correct Answer
D. Bursts
Explanation
Bursts are not normally associated with castings. Bursts refer to the rupturing or cracking of the mold during the casting process due to excessive internal pressure. This can result from factors such as improper gating or excessive pouring temperature. However, other discontinuities like segregation, core shift, and misrun are commonly associated with castings. Segregation refers to the non-uniform distribution of alloying elements, core shift occurs when the core is not properly aligned with the mold, and misrun happens when the molten metal does not completely fill the mold cavity.
35.
Which of the following is identified as a casting insert?
Correct Answer
A. Chaplet
Explanation
A chaplet is a type of casting insert that is used to support or hold a core in place during the casting process. It is typically made of metal and is placed between the mold and the core to provide support and prevent distortion or movement. Chaplets are commonly used in sand casting and other casting processes to ensure the integrity and accuracy of the final casting.
36.
The work metal for working with a forging hammer is:
Correct Answer
D. Any of the above
Explanation
The work metal for working with a forging hammer can be any of the above options mentioned, which are a bloom, a billet, or a bar. This means that all three forms of metal can be used as the workpiece when using a forging hammer. The choice of which form to use would depend on the specific requirements of the forging process and the desired outcome.
37.
Cold working steel or aluminum results in a decrease in:
Correct Answer
A. Ductility
Explanation
Cold working steel or aluminum involves subjecting the material to mechanical stress at low temperatures. This process causes the material to become harder and stronger due to the formation of dislocations and grain boundaries. However, it also leads to a decrease in ductility, which refers to the ability of a material to deform under tensile stress without breaking. Therefore, the correct answer is ductility.
38.
The grain size of ferrous metal is commonly refined by:
Correct Answer
B. Heat treatment
Explanation
Heat treatment is a commonly used method to refine the grain size of ferrous metals. During heat treatment, the metal is heated to a specific temperature and then cooled at a controlled rate. This process helps in rearranging the atoms within the metal, resulting in a finer and more uniform grain structure. By controlling the temperature and cooling rate, the grain size can be effectively reduced, leading to improved mechanical properties such as increased strength and hardness. Elastic deformation and high frequency mechanical vibrations are not commonly used methods for refining the grain size of ferrous metals.
39.
A method commonly used to remove a number of flaws in an ingot prior to forming is:
Correct Answer
A. Cropping
Explanation
Cropping is a method commonly used to remove a number of flaws in an ingot prior to forming. This process involves cutting off the defective or unwanted parts of the ingot, such as cracks, impurities, or uneven surfaces. By removing these flaws, cropping helps to improve the overall quality and integrity of the ingot, making it more suitable for further processing and forming into desired shapes or products. Heat treating, welding, and sand blasting are not typically used for removing flaws in ingots.
40.
Which of the following factors can have a negative influence on some non-destructive tests?
Correct Answer
D. All of the above
Explanation
All of the factors mentioned (grain size, grain orientation, and grain boundary composition) can have a negative influence on some non-destructive tests. This is because these factors can affect the propagation of waves or the interaction of radiation with the material being tested. For example, variations in grain size or orientation can cause scattering or diffraction of waves, making it difficult to accurately interpret the test results. Similarly, differences in grain boundary composition can affect the transmission or reflection of waves, leading to inaccuracies in the test measurements. Therefore, all of these factors can potentially impact the reliability and accuracy of non-destructive tests.
41.
The principal purpose of risers in molds is to:
Correct Answer
A. Feed the castings
Explanation
Risers, also known as feeders, are used in casting processes to provide additional molten metal to compensate for shrinkage during solidification. This helps ensure that the casting fills completely and avoids defects such as shrinkage voids.
42.
The process in which a mold is formed from a mixture of sand and a thermosetting resin binder that is placed against a heated metal pattern is called:
Correct Answer
D. Shell molding
Explanation
Shell molding is the correct answer because it involves the formation of a mold using a mixture of sand and a thermosetting resin binder. This mixture is placed against a heated metal pattern to create the mold. Shell molding is a type of casting process that allows for the production of complex and detailed parts with high dimensional accuracy.
43.
A casting process in which the pattern is not re-usable is called:
Correct Answer
B. Investment casting
Explanation
Investment casting is a casting process in which a pattern is created from wax or a similar material, and then coated with a ceramic material. The ceramic shell is then heated to remove the wax, leaving behind a hollow cavity in the shape of the desired part. Molten metal is then poured into the cavity, creating the final casting. Unlike other casting processes, investment casting does not involve the use of a reusable pattern. Instead, each pattern is destroyed in the process, making it a non-reusable casting method.
44.
A casting process involving a re-usable mold is called:
Correct Answer
D. Die casting
Explanation
Die casting is the correct answer because it refers to a casting process that involves pouring molten metal into a reusable mold, usually made of steel. The molten metal is forced into the mold under high pressure, allowing for the production of complex shapes with high precision and surface finish. This process is commonly used for manufacturing parts with thin walls, such as automotive components and consumer electronics.
45.
Which of the following welding processes does not involve melting of the parts to be joined?
Correct Answer
C. Pressure welding
Explanation
Pressure welding does not involve melting of the parts to be joined. In this process, the parts are joined together by applying pressure, without the need for melting. This can be achieved through various methods such as friction, ultrasonic vibrations, or explosives. Pressure welding is commonly used for joining materials that are difficult to melt or materials that have different melting points.
46.
In the shielded metal-arc process, the electrode covering may include materials used to:
Correct Answer
D. All of the above
Explanation
The electrode covering in the shielded metal-arc process serves multiple purposes. Firstly, it protects the metal from oxidation during the melting and transfer process across the arc. This is important to prevent any contamination or weakening of the weld. Secondly, it protects the weld bead as it solidifies and cools to room temperature, ensuring that it maintains its integrity and strength. Lastly, the electrode covering can also be used to alloy the weld metal, adding specific elements to enhance its properties. Therefore, all of the given options are correct.
47.
A non-consumable electrode used for arc welding would be made of:
Correct Answer
A. Tungsten
Explanation
A non-consumable electrode used for arc welding would be made of tungsten because it has a high melting point and excellent heat resistance. Tungsten is able to withstand the extreme temperatures generated during the welding process without melting or being consumed, making it an ideal choice for non-consumable electrodes.
48.
In gas welding, the acetylene is usually burned with:
Correct Answer
A. Oxygen
Explanation
In gas welding, acetylene is typically burned with oxygen. This is because acetylene requires oxygen to support combustion and produce a high-temperature flame necessary for welding. Oxygen acts as the oxidizer, reacting with acetylene to generate heat and create a stable flame. Hydrogen, argon, and nitrogen are not commonly used as the primary gas for burning acetylene in gas welding processes.
49.
Which of the following statements is correct?
Correct Answer
B. In some areas of the weld heat affected zone, grain size can be smaller than in the unaffected base metal
Explanation
This statement is correct because the heat-affected zone (HAZ) is a region of the base metal that has been affected by the heat from welding. In some cases, the HAZ can have variations in microstructure, including changes in grain size, due to the rapid heating and cooling during the welding process. So, it's possible for the grain size to be smaller in some areas of the HAZ compared to the unaffected base metal.
50.
A rupture in the material that can be in any direction on the part and is caused by localized stresses that exceed the tensile strength of the material is:
Correct Answer
B. A heat treat crack
Explanation
A heat treat crack is a rupture or crack that occurs in a material due to localized stresses that exceed the material's tensile strength, often as a result of the heat treatment process. This process involves heating and cooling metal to alter its physical properties, which can sometimes introduce residual stresses or uneven cooling. If these stresses exceed the tensile strength, cracks may form, potentially in any direction. Heat treat cracks can compromise the integrity and durability of a part, and their formation might require adjustments to heat treatment methods or improved stress-relief processes to prevent reoccurrence. User