Advanced Diagnostics & Troubleshooting Flashcards

A SAW operator notices that the arc voltage meter reads normal but depth of penetration is much shallower than the WPS requires. Which condition is most likely?

Answer: Electrode extension (stickout) is too long

Excessive electrode extension increases resistance heating in the wire, reducing the arc energy available for penetration despite a normal voltage reading at the power source.

Weld metal oxygen content is found to be excessively high on a SAW procedure qualification test. Which flux parameter should be reviewed?

Answer: Flux basicity index (BI)

A low basicity index (acidic flux) transfers more oxygen to the weld metal; selecting a higher-BI flux reduces weld metal oxygen content.

During SAW of a thick plate, radiographic inspection shows a planar lack-of-fusion indication at the weld root after a double-sided procedure. The most likely cause is:

Answer: Insufficient back-gouge depth to remove the initial root pass

If back-gouging does not reach sound metal, residual root defects remain unfused when the second-side SAW passes are deposited.

A SAW power source trips on overtemperature repeatedly during a long production run. The cooling fan is functioning. What is the most logical next diagnostic step?

Answer: Check duty cycle against the actual arc-on time percentage

If arc-on time exceeds the power source rated duty cycle, internal components overheat; reducing arc-on time or using a higher-rated machine resolves the issue.

Slag inclusions are found at the inter-run boundaries of a multi-pass SAW weld. What corrective action is most appropriate?

Answer: Improve inter-pass slag removal and ensure bead profile is flat before next pass

Residual slag trapped in bead valleys or undercuts is covered by the next pass, creating slag inclusions; thorough removal and flat bead profiles prevent entrapment.

A SAW wire feeder displays a 'wire slip' alarm intermittently, and the amperage fluctuates. After confirming the wire spool is free-turning, what is the next item to inspect?

Answer: Drive roll condition and tension setting

Worn, mismatched, or improperly tensioned drive rolls cause intermittent wire slip that produces current fluctuations and unstable arc conditions.

A weld made on HY-80 steel using SAW fails a Charpy impact test at the required temperature. The WPS-specified flux and wire were used correctly. What metallurgical factor should be investigated?

Answer: Interpass temperature exceeding the maximum allowed value

Excessively high interpass temperatures coarsen the heat-affected zone and weld metal microstructure, significantly reducing Charpy impact toughness in quenched-and-tempered steels.