WCL Welding Processes & Techniques 4 — Questions and Answers
Question 1: What is 'globular transfer' in GMAW and when does it typically occur?
- Small fine droplets transferred at high frequency
- Large irregular droplets that transfer across the arc, often with spatter, at intermediate voltage/amperage (Correct answer)
- Wire touching the puddle with no visible arc
- Metal transferred without any spatter at very high voltage
Correct answer: Large irregular droplets that transfer across the arc, often with spatter, at intermediate voltage/amperage
Globular transfer produces large, irregular molten droplets that fall across the arc under gravity, causing significant spatter at intermediate voltage settings.
Question 2: In submerged arc welding (SAW), what function does the granular flux serve?
- It acts as filler metal only
- It shields the arc and weld pool from atmosphere, and can add alloying elements to the weld (Correct answer)
- It generates the arc between the wire and workpiece
- It only cleans the base metal surface before welding
Correct answer: It shields the arc and weld pool from atmosphere, and can add alloying elements to the weld
In SAW, the granular flux blankets the arc and molten pool to provide atmospheric shielding and can contribute alloying elements to the weld metal.
Question 3: What does 'stringer bead' mean in welding technique?
- A bead made with a wide side-to-side weaving motion
- A narrow bead deposited by moving the electrode straight along the joint with little or no weaving (Correct answer)
- A root pass deposited with high heat input
- A bead used only in overhead welding
Correct answer: A narrow bead deposited by moving the electrode straight along the joint with little or no weaving
A stringer bead is deposited by moving the electrode along the joint in a straight line without lateral weaving, producing a narrow, consistent bead.
Question 4: Which type of joint is created when two pieces of metal are placed end-to-end in the same plane and welded?
- Lap joint
- T-joint
- Corner joint
- Butt joint (Correct answer)
Correct answer: Butt joint
A butt joint is formed when two pieces are placed end-to-end in the same plane and welded along their edges.
Question 5: What is the significance of the 'duty cycle' rating on a welding power source?
- The maximum amperage the machine can produce at any time
- The percentage of a 10-minute period the machine can weld at a rated amperage without overheating (Correct answer)
- The number of hours between required maintenance intervals
- The ratio of open-circuit voltage to welding voltage
Correct answer: The percentage of a 10-minute period the machine can weld at a rated amperage without overheating
Duty cycle indicates the percentage of a 10-minute period a machine can operate at its rated output before needing to cool down to prevent overheating.
Question 6: When GTAW welding stainless steel, what contamination can occur if the tungsten electrode accidentally contacts the weld pool?
- Porosity from nitrogen absorption
- Tungsten inclusions in the weld metal (Correct answer)
- Excessive spatter on the base metal
- Hydrogen-induced cracking in the HAZ
Correct answer: Tungsten inclusions in the weld metal
If the tungsten electrode touches the weld pool, tungsten particles can become embedded in the weld, causing tungsten inclusions that are a rejectable discontinuity.
Question 7: What is the AWS definition of a 'groove weld'?
- A weld made in the groove between two members to be joined (Correct answer)
- A fillet weld deposited at the root of a T-joint
- A weld used only on pipe joints
- A weld made on the surface of a base metal to restore thickness
Correct answer: A weld made in the groove between two members to be joined
A groove weld is deposited in a groove between two members to join them, providing full or partial joint penetration depending on the joint design.
WCL Welding Processes & Techniques 4
What is 'globular transfer' in GMAW and when does it typically occur?