Certified Welder Welding Processes & Techniques 3 — Questions and Answers
Question 1: When performing an uphill vertical weld with SMAW, the welder should use which technique to control the molten pool?
- Faster travel speed with a straight stringer bead
- A weaving motion with brief pauses at the toes (Correct answer)
- Larger electrode diameter for more heat input
- Downhill progression for better fusion
Correct answer: A weaving motion with brief pauses at the toes
Uphill vertical welding uses a weaving pattern with brief pauses at the toes to allow the puddle to fuse and prevent sagging.
Question 2: Which welding position is designated as '2G' according to AWS classification?
- Flat groove weld
- Horizontal groove weld (Correct answer)
- Vertical groove weld
- Overhead groove weld
Correct answer: Horizontal groove weld
The '2G' designation indicates a horizontal groove weld position where the axis of the weld is horizontal.
Question 3: What is the purpose of a 'hot pass' in multi-pass pipe welding?
- The final cosmetic cap pass applied at high amperage
- A pass immediately after the root pass to burn out inclusions and tie in the toes (Correct answer)
- A preheat applied by torch before welding
- A high-speed pass used only in automated welding
Correct answer: A pass immediately after the root pass to burn out inclusions and tie in the toes
The hot pass follows the root pass immediately, using higher heat to burn out trapped slag and gas and ensure proper fusion at the root.
Question 4: In GMAW, what effect does increasing wire feed speed have?
- Decreases welding current and reduces penetration
- Increases welding current and increases heat input (Correct answer)
- Has no effect on amperage, only travel speed
- Decreases voltage and narrows the bead
Correct answer: Increases welding current and increases heat input
In GMAW, the wire feed speed directly controls amperage; faster wire feed increases current draw and raises heat input.
Question 5: Which shielding gas is commonly used for GMAW of stainless steel to prevent carbide precipitation and improve arc stability?
- 100% CO2
- 100% argon
- Tri-mix (He/Ar/CO2) (Correct answer)
- 100% helium
Correct answer: Tri-mix (He/Ar/CO2)
A tri-mix of helium, argon, and a small percentage of CO2 is commonly used for stainless steel GMAW to provide good arc stability and prevent sensitization.
Question 6: What is 'arc blow' and which current type most commonly causes it?
- Excess spatter caused by AC welding on thin metals
- Magnetic deflection of the arc, most common with DC welding (Correct answer)
- Arc instability caused by contaminated shielding gas
- Electrode sticking caused by too-low amperage on DCEP
Correct answer: Magnetic deflection of the arc, most common with DC welding
Arc blow is the deflection of the welding arc caused by magnetic fields, and it most commonly occurs with DC welding on ferromagnetic materials.
Question 7: When welding with GTAW on thin stainless steel sheet, why might the welder use a trailing gas shield?
- To preheat the base metal ahead of the weld
- To protect the hot weld metal from oxidation after the torch passes (Correct answer)
- To cool the weld faster and reduce distortion
- To add filler metal to the weld pool remotely
Correct answer: To protect the hot weld metal from oxidation after the torch passes
A trailing gas shield directs inert gas over the weld bead as the torch moves forward, preventing oxidation (sugaring) of the hot stainless steel.
Certified Welder Welding Processes & Techniques 3
When performing an uphill vertical weld with SMAW, the welder should use which technique to control the molten pool?