Lec 19: Other Welding Processes
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Questions and Answers

What is the primary purpose of Thermit Welding (TW)?

  • To weld dissimilar metals
  • To join thick plates and large sections
  • To weld steels and cast irons (correct)
  • To weld without the need for fillers

    • Electroslag Welding (ESW) is used for joining thin plates and small sections.

    False

    What is the heat source in Electroslag Welding (ESW)?

    The passage of electrical current through a pool of electrically conductive liquid slag.

    Electron Beam Welding (EBW) is used for joining metals that cannot be welded through ______________ means.

    <p>conventional</p> Signup and view all the answers

    Match the welding process with its characteristic:

    <p>Thermit Welding = Welds steels and cast irons Electroslag Welding = Used for joining thick plates and large sections Electron Beam Welding = Uses a beam of high-velocity electrons Laser Beam Welding = Requires proper preparation and cleaning of surfaces</p> Signup and view all the answers

    What is the purpose of the assist gas in Laser Beam Cutting?

    <p>To cool the workpiece</p> Signup and view all the answers

    Laser Beam Welding (LBW) is used for welding with the need for fillers.

    <p>False</p> Signup and view all the answers

    What is the primary advantage of Electron Beam Welding (EBW)?

    <p>It can be used for joining metals that cannot be welded through conventional means.</p> Signup and view all the answers

    In Electroslag Welding (ESW), the molten slag melts the edges of the pieces that are being joined, as well as continuously fed ______________ electrodes.

    <p>solid or flux-cored</p> Signup and view all the answers

    What is the purpose of the assist gas in laser-beam cutting?

    <p>To propel the molten droplets from the cut</p> Signup and view all the answers

    Laser spot welding requires water cooling.

    <p>False</p> Signup and view all the answers

    What is the advantage of laser spot welding in terms of material resistance?

    <p>The weld quality is independent of material resistance.</p> Signup and view all the answers

    Flash welding is used to produce _______________ welds between similar or dissimilar metals.

    <p>butt</p> Signup and view all the answers

    What is the purpose of the electric current in flash welding?

    <p>To provide optional preheat</p> Signup and view all the answers

    Percussion welding is a type of flash welding that uses a slow discharge of stored energy.

    <p>False</p> Signup and view all the answers

    Match the following welding processes with their characteristics:

    <p>Laser spot welding = Produces no indentations Flash welding = Used to produce butt welds between similar or dissimilar metals Percussion welding = A rapid discharge of stored energy produces a brief period of arcing Upset welding = Similar to flash welding but without the arc</p> Signup and view all the answers

    What is the advantage of laser spot welding in terms of access to the joint?

    <p>Can be performed with access to only one side of the joint</p> Signup and view all the answers

    The laser provides the heat, and the flow of assist gas propels the molten droplets from the _______________.

    <p>cut</p> Signup and view all the answers

    Laser spot welding requires electrodes.

    <p>False</p> Signup and view all the answers

    What is the function of the magnesium fuse in Thermit Welding (TW)?

    <p>To ignite the thermit mixture</p> Signup and view all the answers

    Electroslag Welding (ESW) is used for joining thin plates and small sections.

    <p>False</p> Signup and view all the answers

    What is the purpose of the solidification control in Electroslag Welding (ESW)?

    <p>To control the cooling rate and prevent grain growth</p> Signup and view all the answers

    In Electron Beam Welding (EBW), the metal to be welded is heated by the impingement of a beam of high-velocity ______________________.

    <p>electrons</p> Signup and view all the answers

    Match the welding process with its characteristic:

    <p>Electron Beam Welding (EBW) = Uses a pool of electrically conductive liquid slag Laser Beam Welding (LBW) = Uses a laser beam to heat the metal, no need of fillers, autogenous welding Thermit Welding (TW) = One part aluminum, three parts iron oxide and lit by a magnesium fuse Electroslag Welding (ESW) = Uses a pool of electrically conductive liquid slag</p> Signup and view all the answers

    What is the purpose of the assist gas in Laser Beam Cutting?

    <p>To participate in a combustion reaction with the material being cut</p> Signup and view all the answers

    Laser Beam Welding (LBW) requires filler material.

    <p>False</p> Signup and view all the answers

    What is the purpose of the laser beam in Laser Beam Welding (LBW)?

    <p>To heat the metal</p> Signup and view all the answers

    In Electroslag Welding (ESW), the molten slag melts the edges of the pieces that are being joined, as well as continuously fed ______________________ electrodes.

    <p>solid or flux-cored</p> Signup and view all the answers

    What is the advantage of Electron Beam Welding (EBW)?

    <p>It can weld metals that cannot be welded through conventional means</p> Signup and view all the answers

    What is the role of the assist gas in laser-beam cutting?

    <p>To propel the molten droplets from the cut</p> Signup and view all the answers

    Laser spot welding requires access to both sides of the joint.

    <p>False</p> Signup and view all the answers

    What is the primary purpose of the electric current in flash welding?

    <p>To provide optional preheat.</p> Signup and view all the answers

    The laser provides the heat, and the flow of assist gas propels the molten droplets from the _______________________.

    <p>cut</p> Signup and view all the answers

    Match the following welding processes with their characteristics:

    <p>Flash Welding = Produces butt welds between similar or dissimilar metals Laser Spot Welding = Non-contact process with no electrodes needed Percussion Welding = Rapid discharge of stored energy produces a brief period of arcing</p> Signup and view all the answers

    Upset Welding (UW) is similar to flash welding with an arc.

    <p>False</p> Signup and view all the answers

    What is the advantage of laser spot welding in terms of material resistance?

    <p>It is independent of material resistance</p> Signup and view all the answers

    What is the primary advantage of laser spot welding?

    <p>No indentation is produced.</p> Signup and view all the answers

    Flash welding is used to produce _______________________ welds between similar or dissimilar metals.

    <p>butt</p> Signup and view all the answers

    Study Notes

    Thermit Welding (TW)

    • Uses a mixture of aluminum and iron oxide that is lit by a magnesium fuse
    • Produces a superheated molten iron that melts and flows into the prepared joint
    • Suitable for welding steels and cast irons

    Electroslag Welding (ESW)

    • Used for joining thick plates and large sections
    • Heat is derived from the passage of an electric current through a pool of electrically conductive liquid slag
    • Molten slag melts the edges of the pieces being joined and continuously fed solid or flux-cored electrodes
    • Has slow cooling and a large heat-affected zone (HAZ), leading to extensive grain growth

    Electron Beam Welding (EBW)

    • Heats the metal to be welded through the impingement of a high-velocity electron beam
    • Used for joining metals that cannot be welded through conventional means
    • Suitable for joining dissimilar metals

    Laser Beam Welding (LBW)

    • Used for autogenous welding without the need for fillers
    • Requires proper preparation and cleaning of surfaces to be welded
    • Can be used for laser-beam cutting and laser spot welding

    Laser Beam Cutting

    • Uses an assist gas to cool the workpiece, minimize the HAZ, and participate in a combustion reaction with the material being cut
    • Different assist gases are used for different metals:
      • Oxygen for mild steel
      • Nitrogen for stainless steel and aluminum
      • Argon for titanium
      • Inert gases or air for nonmetallics
    • Cutting speed is set by the rate at which the laser can melt or vaporize the material

    Laser Spot Welding

    • A non-contact process that can be performed with access to only one side of the joint
    • Produces no indentations and does not require electrodes or water cooling
    • Weld quality is independent of material resistance, surface resistance, and electrode condition
    • Total heat input is low

    Flash Welding (FW)

    • Used to produce butt welds between similar or dissimilar metals in solid or tubular form
    • Involves securing two pieces of metal in current-carrying grips, lightly touching them together, and then withdrawing them slightly
    • An intense flashing arc forms across the gap, melting the material on both surfaces, before the pieces are forced together under high pressure

    Variations of Flash Welding

    • Percussion welding (PEW): a rapid discharge of stored energy produces a brief period of arcing, followed by the rapid application of force to expel the molten metal and produce the joint
    • Upset Welding (UW): similar to flash welding but without the arc

    Thermit Welding (TW)

    • Uses a mixture of aluminum and iron oxide that is lit by a magnesium fuse
    • Produces a superheated molten iron that melts and flows into the prepared joint
    • Suitable for welding steels and cast irons

    Electroslag Welding (ESW)

    • Used for joining thick plates and large sections
    • Heat is derived from the passage of an electric current through a pool of electrically conductive liquid slag
    • Molten slag melts the edges of the pieces being joined and continuously fed solid or flux-cored electrodes
    • Has slow cooling and a large heat-affected zone (HAZ), leading to extensive grain growth

    Electron Beam Welding (EBW)

    • Heats the metal to be welded through the impingement of a high-velocity electron beam
    • Used for joining metals that cannot be welded through conventional means
    • Suitable for joining dissimilar metals

    Laser Beam Welding (LBW)

    • Used for autogenous welding without the need for fillers
    • Requires proper preparation and cleaning of surfaces to be welded
    • Can be used for laser-beam cutting and laser spot welding

    Laser Beam Cutting

    • Uses an assist gas to cool the workpiece, minimize the HAZ, and participate in a combustion reaction with the material being cut
    • Different assist gases are used for different metals:
      • Oxygen for mild steel
      • Nitrogen for stainless steel and aluminum
      • Argon for titanium
      • Inert gases or air for nonmetallics
    • Cutting speed is set by the rate at which the laser can melt or vaporize the material

    Laser Spot Welding

    • A non-contact process that can be performed with access to only one side of the joint
    • Produces no indentations and does not require electrodes or water cooling
    • Weld quality is independent of material resistance, surface resistance, and electrode condition
    • Total heat input is low

    Flash Welding (FW)

    • Used to produce butt welds between similar or dissimilar metals in solid or tubular form
    • Involves securing two pieces of metal in current-carrying grips, lightly touching them together, and then withdrawing them slightly
    • An intense flashing arc forms across the gap, melting the material on both surfaces, before the pieces are forced together under high pressure

    Variations of Flash Welding

    • Percussion welding (PEW): a rapid discharge of stored energy produces a brief period of arcing, followed by the rapid application of force to expel the molten metal and produce the joint
    • Upset Welding (UW): similar to flash welding but without the arc

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    Other Welding Processes PDF

    Description

    Learn about Thermit Welding, a process used to weld steels and cast irons, and its application in Mechanical Engineering.

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