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Questions and Answers
What is the characteristic of the heating effect in Direct Current Reverse Polarity (DCRP) when applied in welding?
What is the characteristic of the heating effect in Direct Current Reverse Polarity (DCRP) when applied in welding?
Which welding joint is specifically designed to join two members aligned in the same plane?
Which welding joint is specifically designed to join two members aligned in the same plane?
What type of weld is primarily used to fill in the edges of plates associated with corner, lap, and tee joints?
What type of weld is primarily used to fill in the edges of plates associated with corner, lap, and tee joints?
Which welding method achieves a penetration depth that is approximately halfway between direct current straight polarity and reverse polarity?
Which welding method achieves a penetration depth that is approximately halfway between direct current straight polarity and reverse polarity?
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What is a common shape used for grooves in groove welds?
What is a common shape used for grooves in groove welds?
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What minimum requirement is needed for a fillet weld?
What minimum requirement is needed for a fillet weld?
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Which joint is used to join the edges of members running at right angles to each other?
Which joint is used to join the edges of members running at right angles to each other?
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Which of the following is NOT a type of groove shape associated with groove welds?
Which of the following is NOT a type of groove shape associated with groove welds?
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What penetration characteristic does Direct Current Reverse Polarity (DCRP) provide in welding?
What penetration characteristic does Direct Current Reverse Polarity (DCRP) provide in welding?
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During which welding method is the electrode positive while the workpiece is negative?
During which welding method is the electrode positive while the workpiece is negative?
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What is the purpose of the flux coating on the electrode in Shielded-metal Arc Welding (SMAW)?
What is the purpose of the flux coating on the electrode in Shielded-metal Arc Welding (SMAW)?
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In SMAW, what initiates the electric arc?
In SMAW, what initiates the electric arc?
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Which component of SMAW equipment is responsible for connecting the workpiece to the electrical circuit?
Which component of SMAW equipment is responsible for connecting the workpiece to the electrical circuit?
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What type of polarity in SMAW has the workpiece connected to the positive side of the circuit?
What type of polarity in SMAW has the workpiece connected to the positive side of the circuit?
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Which of the following is NOT a component of SMAW equipment?
Which of the following is NOT a component of SMAW equipment?
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What is the role of the electrode in the SMAW process?
What is the role of the electrode in the SMAW process?
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What type of electrical current flows in one direction only in an arc welding circuit?
What type of electrical current flows in one direction only in an arc welding circuit?
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Which statement about Direct Current Reverse Polarity (DCRP) is true?
Which statement about Direct Current Reverse Polarity (DCRP) is true?
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In the SMAW process, what happens to the electrode as the arc is struck?
In the SMAW process, what happens to the electrode as the arc is struck?
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Which of the following safety equipment is NOT typically required during SMAW?
Which of the following safety equipment is NOT typically required during SMAW?
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Which type of groove weld is specifically mentioned for thicker sections?
Which type of groove weld is specifically mentioned for thicker sections?
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What is the main function of a welding rod?
What is the main function of a welding rod?
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Which type of electrode does not provide filler metal to the joint?
Which type of electrode does not provide filler metal to the joint?
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What does the term 'flux' refer to in welding processes?
What does the term 'flux' refer to in welding processes?
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Which of the following is NOT classified as a welding defect?
Which of the following is NOT classified as a welding defect?
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Which of the following describes a consumable electrode?
Which of the following describes a consumable electrode?
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What is the purpose of the filler material in welding?
What is the purpose of the filler material in welding?
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Which welding defect is characterized by visible holes in the weld?
Which welding defect is characterized by visible holes in the weld?
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Which of the following groove welds has a single groove shape?
Which of the following groove welds has a single groove shape?
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Which welding defect refers to a lack of complete merging between two metals?
Which welding defect refers to a lack of complete merging between two metals?
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Study Notes
Welding Processes
- Welding is a fabrication process that joins materials using heat or pressure, or both, to produce coalescence.
- Welding Classifications:
- Arc welding
- Gas-metal arc welding (GMAW)
- Gas tungsten arc welding (GTAW)
- Shielded metal arc welding (SMAW)
- Submerged arc welding (SAW)
- Solid-state welding (SSW)
- Brazing
- Soldering
- Thermal Spraying
- Allied Processes
- Oxy-fuel gas welding
- Electric arc spraying
- Cutting
- Arc cutting
- Chemical-flux cutting
- Oxy-fuel gas cutting
- Plasma arc cutting
- Laser-beam cutting
- Other
- Arc welding
Shielded Metal Arc Welding (SMAW)
- Most common type of arc welding.
- Uses a consumable covered electrode (metal wire).
- Electrode includes a core wire surrounded by a flux coating.
- Flux melts to protect the weld area from contamination.
- Electrode also melts and combines with molten base metal as filler.
SMAW Principle and Equipment
- Electrode and workpiece form an electrical circuit.
- Two cables from power source: one to the workpiece, one to the electrode holder.
- Striking the arc: electrode slightly touches the workpiece, then pulled back.
- Initiates arc and melting, with electrode droplets moving to the weld pool.
SMAW Equipment Components
- Welding generator (DC or AC transformer)
- Two cables (one for workpiece, one for electrode)
- Ground clamp
- Electrode holder
- Protective shield
- Gloves
- Wire brush
- Chipping hammer
SMAW Polarity
- Polarity refers to the direction of current flow in a DC electrical circuit.
- Two types for DC circuit:
- Direct current straight polarity (DCSP)
- Direct current reverse polarity (DCRP)
- Workpiece connected to the positive side.
- Electrode attached to the negative side in DCSP.
- More power at the work end of the arc with less at electrode end in DCSP.
- In DCRP, the work is negative and the
- Electrode is positive.
- Electrode receives more of the heating effect in DCRP.
SMAW Alternating Current (AC)
- AC combines deep penetration and shallow penetration characteristics.
- Penetration depth is approximately halfway between DCSP and DCRP.
Types of Welding Joints
- Butt joint: Joining two aligned members.
- Corner joint: Joining two members at a right angle.
- Edge joint: Joining edges of two or more members lying on the same plane.
- Lap joint: One member laid over another.
- Tee joint: Two members at right angles, joined by one piece.
Types of Welds
-
Fillet weld:
-
Used to fill in corners, laps, and tees.
-
Approximate shape of a right triangle.
-
Most common type in arc and oxy-fuel welding.
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Requires minimal edge preparation.
-
Groove Weld:
-
Requires part edges shaped into groove for weld penetration.
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Grooved shapes include square, bevel, V, U, and J, in single or double sides.
-
Most closely associated with butt joints.
Welding Defects
- Slag inclusions
- Gas porosity
- Incomplete fusion
- Incomplete penetration
- Excessive penetration
- Spatter
- Cracks
- Undercut
- Underfill
Welding Terminology
- Filler Material: Material added to space between the joint during welding
- Welding Rod: Filler metal that does not conduct electricity.
- Electrode: Conducts current from electrode holder to the metal being welded. Consumable or non-consumable.
- Consumable Electrode: Provides a current path and filler metal.
- Non-Consumable Electrode: Used as a conductor for current in certain welding styles.
- Flux: Material used to dissolve oxides and release slag. (Powder,liquid, or paste form.)
- Deposited Metal: Material in weld created by electrode or filler wire.
- Base Metal: The original piece that is welded, soldered or cut.
- Weld Metal: Portion of a weld melted during welding.
- Weld Pool: Area of a weld where the base metal has reached its melting point.
- Heat-affected zone (HAZ): Area near weld that hasn't melted, but structure or properties are changed.
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