AWS AWS Weld Metallurgy & Heat Treatment 3

Question 1

The primary purpose of preheating before welding is to:

Accepted Answer

Reduce the risk of hydrogen-induced cracking by slowing the cooling rate

Answer

Preheat slows the cooling rate of the weld and HAZ, allowing hydrogen to diffuse out and reducing the risk of hydrogen-induced cracking and martensitic transformation.

Question 2

The minimum preheat temperature for a given steel is primarily determined by:

Accepted Answer

The carbon equivalent and thickness of the base metal

Answer

Minimum preheat temperature is determined by the carbon equivalent (CE) of the steel and the section thickness, as specified in codes like AWS D1.1.

Question 3

Interpass temperature refers to:

Accepted Answer

The maximum temperature of the weld zone between successive weld passes

Answer

Interpass temperature is the temperature of the weld zone immediately before depositing the next pass, and has a maximum limit to prevent degradation of mechanical properties.

Question 4

Post-weld heat treatment (PWHT) is primarily used to:

Accepted Answer

Relieve residual stresses and temper hard microstructures

Answer

PWHT reduces residual stresses from welding, tempers hard martensitic structures, and improves toughness and dimensional stability.

Question 5

For carbon steel, a typical stress relief PWHT temperature range is:

Accepted Answer

1000–1200°F (538–649°C)

Answer

Carbon and low-alloy steels are typically stress relieved at 1000–1200°F (538–649°C), which is below the lower critical transformation temperature.

AWS Practice Test

AWS Practice Test

AWS AWS Weld Metallurgy & Heat Treatment 3