CWI Weld Discontinuities and Defects 2

Question 1

Which discontinuity 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 or root that is not filled by weld metal, reducing the effective cross-section.

Question 2

Lamellar tearing in a weld joint is most likely to occur in which orientation relative to the base metal surface?

Accepted Answer

Parallel to the surface

Answer

Lamellar tearing occurs parallel to the plate surface due to through-thickness stresses acting on planes of low ductility inclusions.

Question 3

A weld that shows excessive convexity is most likely to cause which problem in service?

Accepted Answer

Stress concentration at the weld toes

Answer

Excessive convexity creates stress concentrations at the weld toes due to the abrupt geometric transition, which can initiate fatigue cracking.

Question 4

Which type of crack propagates along the weld metal centerline, typically caused by solidification shrinkage and low-melting-point constituents?

Accepted Answer

Longitudinal centerline crack

Answer

Longitudinal centerline cracks form along the weld axis as the weld solidifies, driven by shrinkage stresses and segregation of low-melting impurities.

Question 5

According to AWS standards, which condition describes 'overlap' in a weld?

Accepted Answer

Protrusion of weld metal beyond the weld toe onto base metal without fusion

Answer

Overlap is the protrusion of weld metal beyond the weld toe or root onto the base metal surface without fusion, creating a notch-like condition.

CWI Practice Test

CWI Practice Test

CWI Weld Discontinuities and Defects 2