38 Questions
What is the primary function of the rotating probe in Friction-stir Welding?
To generate frictional heat
Friction-stir Welding involves melting of the material.
False
What happens to the softened material in Friction-stir Welding?
The softened material coalesces and is swept to the back.
What is the purpose of the welding tool in Stir Welding?
To prevent expulsion of softened material from the joint
Match the following welding processes with their characteristics:
Friction Welding = Uses a rotating probe to generate frictional heat Forge Welding = Involves heating and hammering the workpieces Cold Welding = Involves high-pressure bonding at room temperature Inertia Welding = Uses kinetic energy to generate heat
Roll Welding involves the use of a rotating probe.
False
What is shown in Figure 32-19(a) of the Stir Welding example?
The top surface of a friction-stir weld joining 1.5-mm- and 1.65-mm-thick aluminum sheets.
What is the main advantage of Resistance Welding?
Skilled operators not required
Forge Welding is a modern welding process.
False
What is the name of the process that uses conical welding bell or welding rolls to join pipes?
Forge Seam Welding
Cold Welding is a variation of ______________ welding.
Forge
What is the main difference between Forge Welding and Cold Welding?
Temperature of welding
Match the following welding processes with their descriptions:
Forge Seam Welding = Uses conical welding bell or welding rolls Cold Welding = Done at room temperature Roll Welding = Sheets or plates of metal are passed through a rolling mill
Inertia Welding is a type of Solid-State Welding process.
True
What is the name of the welding process that uses high localized pressure to achieve coalescence?
Cold Welding
What is the simplest and most widely used form of resistance welding?
Resistance Spot Welding
A spot-weld nugget formed between two sheets of aluminum alloy is always symmetrical.
False
What should happen to a weld during a tear test?
The weld should remain intact, while failure occurs in the heat-affected zone surrounding the nugget.
A single-phase, air-operated, press-type resistance welder is controlled by a _______________.
microprocessor
What is the primary purpose of electrodes in resistance spot welding?
To conduct electricity
Match the following welding processes with their characteristics:
Resistance Spot Welding = Fast and economical means of joining overlapped materials Projection Welding = Uses an embossment or projection on one of the workpieces Resistance Seam Welding = Continuous welding process
Resistance welding involves forging and postheating operations.
True
What is the name of the device shown in the figure, which is a type of resistive welder?
Single-phase, air-operated, press-type resistance welder
What is the primary mechanism used in Friction Welding?
Friction generated heat
Friction Welding can only be used for steel bars with a diameter of less than 1 inch.
False
What is the main advantage of Inertia Welding?
Consistent weld quality
Inertia Welding is a modification of _______________ welding.
friction
What is the requirement for surfaces to be joined in Friction Welding?
Square-cut, smooth surface
Match the following welding processes with their characteristics:
Friction Welding = Utilizes friction generated heat Inertia Welding = Modifies friction welding and uses a flywheel Cold Welding = Applies high pressure, no heat source Forge Welding = utilizes heat and pressure
What is the advantage of Inertia Welding in terms of speed?
Fast and efficient
What is a disadvantage of Friction-stir Welding?
Large downward force required
Ultrasonic Welding can be used to weld thick sheets.
False
What is the frequency range used in Ultrasonic Welding?
10khz-200khz
In Ultrasonic Welding, the temperature rarely exceeds half of the __________ point.
melting
What is an advantage of Ultrasonic Welding?
Very fast
Match the following welding processes with their characteristics:
Friction-stir Welding = Requires large downward force Ultrasonic Welding = Uses high-frequency vibrations Explosive Welding = Accelerates one of the components through the use of explosives Diffusion Welding = Involves diffusion of atoms
Friction-stir Welding has a high flexibility.
False
What is the limitation of Explosive Welding?
Limited geometry
Study Notes
Friction Welding (FRW)
- Utilizes friction-generated heat
- Surfaces to be joined must have square-cut, smooth surface
- Can be used for steel bars up to 8 inches in diameter or dissimilar metals
Inertia Welding
- Modification of friction welding
- Utilizes a flywheel
- Consistent weld quality since energy stored by the flywheel can be directly controlled for subsequent operations
- Fast and efficient
Friction-Stir Welding (FSW)
- Uses a rotating probe to generate frictional heat
- Material is softened without melting and stirred
- Softened material coalesces and swept to the back
- Features:
- Generates frictional heat
- Provides additional friction heating and prevents expulsion of softened material from the joint
- Applications:
- Example of Stir Welding: friction-stir weld joining 1.5- and 1.65-mm-thick aluminum sheets
Solid-State Welding Processes
- Types:
- Forge welding
- Forge-seam welding
- Cold welding
- Roll welding/ roll bonding
- Friction welding
- Inertia welding
- Friction Stir-Welding
- Ultrasonic Welding
- Diffusion Welding
- Explosive Welding
Forge Welding (FOW)
- Most ancient of welding processes
- Utilized by blacksmiths
- Equipment needed:
- Charcoal forge
- Hammer
- Anvil
- Borax flux
- Procedure:
- Joint preparation → Flux application → Welding
- Pieces to be joined are heated then hammered together until coalescence is achieved
- Results are highly variable
Forge Seam Welding
- Commonly used for pipes
- Uses conical welding bell or welding rolls
- Edges are joined in a lap or butt configuration
Cold Welding
- Variation of forge welding
- Done at room temperature
- Coalescence is achieved by the application of high localized pressure
- Used for soft, ductile materials
Roll Welding/ Roll Bonding (ROW)
- Sheets or plates of metal are passed through a rolling mill
- Can be done hot or cold
- Can be used to join similar or dissimilar metals
Ultrasonic Welding
- Uses high frequency (10kHz-200kHz)
- Temperature rarely exceeds half of melting point
- Restricted to welding thin sheets
- Advantages:
- Very fast
- Clean surface
- Equipment is simple to use
- Disadvantage:
- Limited to welding thin sheets
Diffusion Welding
- Uses high pressure and temperature to bond materials
Explosive Welding
- Accelerates one of the components through the use of explosives
- Limited geometry
Resistance Welding
- Processes:
- Resistance Spot Welding
- Resistance Seam Welding
- Projection Welding
- Advantages:
- Rapid
- Can be fully automated
- Skilled operators not required
- No filler metal, shielding gas, and flux required
- Minimal distortion of the parts being joined
- Dissimilar metal can be joined easily
- High degree of reliability and reproducibility can be achieved
- Limitations:
- High initial cost
- There are limitations to the thickness of material that can be joined
- Lap joints tend to add weight and material
- Access to both sides is usually required
- For some materials, surfaces need special preparation prior to welding
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