AWS AWS Metallurgy & Materials 4

Question 1

What is the primary cause of hydrogen-induced cracking (HIC) in high-strength steel welds?

Accepted Answer

Diffusible hydrogen trapped in the heat-affected zone under tensile stress

Answer

HIC occurs when diffusible hydrogen becomes trapped in the HAZ or weld metal under tensile stress, causing delayed cracking.

Question 2

Which crystal structure is associated with austenitic stainless steel at room temperature?

Accepted Answer

Face-centered cubic (FCC)

Answer

Austenitic stainless steels retain an FCC crystal structure at room temperature due to sufficient austenite-stabilizing elements like nickel.

Question 3

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

Accepted Answer

A specific alloy composition that melts and solidifies at a single temperature

Answer

A eutectic composition is the specific alloy mixture that has the lowest melting point and transforms directly between liquid and solid at a constant temperature.

Question 4

What is the effect of increasing carbon content on the hardenability of steel?

Accepted Answer

Increases hardenability and lowers the Ms temperature

Answer

Higher carbon content increases hardenability (the ability to form martensite) while simultaneously lowering the martensite start (Ms) temperature.

Question 5

Which type of corrosion is most commonly associated with sensitized austenitic stainless steel welds?

Accepted Answer

Intergranular corrosion

Answer

Sensitization causes chromium carbide precipitation at grain boundaries, depleting chromium and making the steel susceptible to intergranular corrosion.

AWS Practice Test

AWS Practice Test

AWS AWS Metallurgy & Materials 4