WCL Metallurgy & Material Science 3

Question 1

What is the significance of the 'carbon equivalent' (CE) formula in welding?

Accepted Answer

It estimates hardenability and cold cracking susceptibility of the base metal

Answer

The CE formula combines carbon and alloying element percentages to estimate how hardenable a steel is and thus how susceptible it is to hydrogen-induced cold cracking.

Question 2

Interpass temperature control during multi-pass welding primarily prevents which metallurgical problem?

Accepted Answer

Excessive grain growth and reduced toughness in the HAZ

Answer

Allowing interpass temperature to become too high causes prolonged exposure to elevated temperatures, promoting coarse grain growth and degrading HAZ toughness.

Question 3

Which type of stainless steel is NOT hardenable by heat treatment?

Accepted Answer

Austenitic stainless steel

Answer

Austenitic stainless steels cannot be hardened by heat treatment because they do not undergo a martensitic transformation; they can only be work-hardened.

Question 4

What is 'hot cracking' (solidification cracking) in welds, and what promotes it?

Accepted Answer

Cracking in the fusion zone during solidification due to low-melting-point segregates

Answer

Hot cracking occurs when low-melting-point compounds (e.g., iron sulfides) segregate to grain boundaries during solidification, forming liquid films that tear under shrinkage stresses.

Question 5

In welding metallurgy, what is the 'heat-affected zone' (HAZ)?

Accepted Answer

The base metal region heated enough to alter its microstructure without melting

Answer

The HAZ is the portion of the base metal adjacent to the fusion zone that is heated sufficiently to cause microstructural changes but does not reach the melting point.

(WCL) Welding Certification Los Angeles Practice Test

(WCL) Welding Certification Los Angeles Practice Test

WCL Metallurgy & Material Science 3