AWS Welding Defects & Quality Control 4

Question 1

Which welding defect is characterized by a groove melted into the base metal adjacent to the weld toe that is left unfilled by weld metal?

Accepted Answer

Undercut

Answer

Undercut is a groove melted into the base metal at the weld toe that remains unfilled, reducing the effective cross-section and creating a stress concentration.

Question 2

A welder notices that the weld metal has rolled over onto the base metal without fusing. This defect is called:

Accepted Answer

Overlap

Answer

Overlap occurs when weld metal flows over the base metal surface without fusing to it, creating a notch-like condition at the toe of the weld.

Question 3

What is the primary cause of lamellar tearing in weldments?

Accepted Answer

Poor through-thickness ductility due to sulfide inclusions

Answer

Lamellar tearing occurs due to poor through-thickness ductility caused by elongated sulfide and silicate inclusions in the base metal, triggered by transverse stresses during welding.

Question 4

Which NDE method is MOST effective for detecting surface-breaking cracks in non-magnetic austenitic stainless steel welds?

Accepted Answer

Liquid penetrant testing (PT)

Answer

Liquid penetrant testing is the preferred surface examination method for non-magnetic materials like austenitic stainless steel, where magnetic particle testing cannot be used.

Question 5

In radiographic testing of welds, a lighter (less dense) area on the film compared to the surrounding base metal typically indicates:

Accepted Answer

A void or porosity

Answer

Voids and porosity appear as lighter areas on radiographic film because they allow more radiation to pass through, creating darker images — but compared to denser base metal, they appear as lighter round indications relative to surrounding structure in standard terminology.

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AWS Welding Defects & Quality Control 4