CWI Metallurgy and Weld Discontinuities 4

Question 1

A tungsten inclusion in a weld is most associated with which welding process?

Accepted Answer

GTAW (Gas Tungsten Arc Welding)

Answer

Tungsten inclusions occur in GTAW when the non-consumable tungsten electrode contacts the weld pool or is contaminated, depositing tungsten particles in the weld.

Question 2

Which of the following best describes 'liquation cracking'?

Accepted Answer

Cracking in the partially melted zone due to segregation of low-melting-point constituents

Answer

Liquation cracking occurs in the partially melted zone (PMZ) or HAZ when low-melting-point grain boundary films form and cannot withstand solidification shrinkage stresses.

Question 3

When inspecting austenitic stainless steel welds, which defect is a primary concern related to sensitization?

Accepted Answer

Carbide precipitation at grain boundaries

Answer

Sensitization in austenitic stainless steel causes chromium carbides to precipitate at grain boundaries, depleting adjacent areas of chromium and reducing corrosion resistance.

Question 4

What does 'interpass temperature' refer to in a multi-pass weld?

Accepted Answer

The maximum or minimum temperature of the weld before starting the next pass

Answer

Interpass temperature is the temperature of the weld joint immediately before depositing the next pass in a multi-pass weld, with both maximum and minimum limits often specified.

Question 5

Which discontinuity involves incomplete bonding between weld passes or between weld metal and base metal, without a groove melted into the base metal?

Accepted Answer

Lack of fusion (LOF)

Answer

Lack of fusion (LOF) is the absence of bonding between weld beads or between weld metal and base metal, caused by insufficient heat input or improper technique.

CWI Practice Test

CWI Practice Test

CWI Metallurgy and Weld Discontinuities 4