SAW Transmission & Drivetrain Systems 3 — Questions and Answers
Question 1: SAW is being used to hard-surface a transfer case output yoke. The ideal interpass temperature limit is set to prevent:
- Excessive grain growth in the heat-affected zone (Correct answer)
- Flux contamination
- Arc blow
- Electrode oxidation
Correct answer: Excessive grain growth in the heat-affected zone
Allowing excessive interpass temperature causes grain coarsening in the HAZ, reducing toughness and fatigue life of the yoke.
Question 2: Which condition indicates that recovered SAW flux is no longer suitable for reuse on drivetrain components?
- Slight color darkening
- Presence of fused slag particles (Correct answer)
- Unusually low arc voltage
- Excess wire feeder speed
Correct answer: Presence of fused slag particles
Fused slag particles in recovered flux cannot melt uniformly and will create inclusions and arc instability in subsequent welds.
Question 3: A planetary gear carrier is rebuilt with multiple SAW passes. Undercut is observed at the weld toes. The primary corrective action is:
- Reduce arc voltage (Correct answer)
- Increase travel speed
- Decrease wire feed speed
- Increase shielding gas flow
Correct answer: Reduce arc voltage
Reducing arc voltage decreases arc width and energy, narrowing the weld bead and eliminating the undercut at the fusion line.
Question 4: For SAW welding of carburized drivetrain components, why is the carburized case typically ground off before welding?
- To reduce weld distortion
- To prevent high-carbon weld metal dilution causing brittleness (Correct answer)
- To allow flux adhesion
- To reduce travel speed requirements
Correct answer: To prevent high-carbon weld metal dilution causing brittleness
The high-carbon carburized layer, if melted into the weld pool, elevates carbon content and promotes crack-susceptible martensite in the deposit.
Question 5: When performing SAW on a large ring gear, the use of run-off tabs at weld end locations primarily prevents:
- Crater cracks and porosity at the weld termination (Correct answer)
- Flux flooding
- Excessive penetration
- Wire feed jams
Correct answer: Crater cracks and porosity at the weld termination
Run-off tabs allow the crater to form and solidify outside the structural weld, preventing the shrinkage cracking and porosity common at weld stops.
Question 6: In SAW of a drive axle flange, magnetic arc blow causes the arc to deflect away from the joint. The best corrective measure is:
- Switching from AC to DC power
- Switching from DC to AC power (Correct answer)
- Increasing wire diameter
- Reducing flux depth
Correct answer: Switching from DC to AC power
AC power constantly reverses current direction, preventing the buildup of a fixed magnetic field that causes arc blow on DC welding.
Question 7: Which SAW wire classification is most appropriate for welding low-alloy, high-strength steel drivetrain components requiring 80 ksi minimum tensile strength?
- EL8
- EM12K
- EH14
- EA2 (Correct answer)
Correct answer: EA2
EA2 is an alloy wire containing manganese and molybdenum that produces weld metal meeting 80 ksi+ tensile requirements for high-strength low-alloy (HSLA) steels.
SAW Transmission & Drivetrain Systems 3
SAW is being used to hard-surface a transfer case output yoke.
The ideal interpass temperature limit is set to prevent: