CWI Metallurgy and Weld Discontinuities 2

Question 1

Which weld discontinuity is caused by the base metal melting away beneath the weld toe, creating a groove along the weld edge?

Accepted Answer

Undercut

Answer

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

Question 2

In welding metallurgy, what does the term 'HAZ' refer to?

Accepted Answer

Heat-Affected Zone

Answer

HAZ stands for Heat-Affected Zone, the region of base metal adjacent to the weld that has had its microstructure altered by welding heat without melting.

Question 3

Which type of crack forms along the centerline of a weld bead due to solidification shrinkage and low-melting-point segregates?

Accepted Answer

Centerline solidification crack

Answer

Centerline solidification cracks occur along the weld centerline as the last liquid to solidify contains low-melting-point impurities that cannot withstand shrinkage stresses.

Question 4

What is the primary cause of porosity in a weld?

Accepted Answer

Gas entrapment during solidification

Answer

Porosity results from gas being trapped in solidifying weld metal, commonly caused by moisture, contamination, or inadequate shielding gas coverage.

Question 5

Which discontinuity occurs when weld metal flows over the base metal surface without fusing to it?

Accepted Answer

Overlap

Answer

Overlap (cold lap) occurs when molten weld metal flows over the base metal surface but fails to fuse with it, creating a sharp notch.

CWI Practice Test

CWI Practice Test

CWI Metallurgy and Weld Discontinuities 2