Architecting on AWS Certification Welding Metallurgy & Materials 3

Question 1

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

Accepted Answer

It estimates hardenability and susceptibility to cold cracking in the HAZ

Answer

The carbon equivalent combines carbon and alloying element content into a single value that predicts HAZ hardenability; higher CE means greater susceptibility to cold cracking and the need for preheat.

Question 2

Which solidification mode in austenitic stainless steel weld metal is most resistant to solidification cracking?

Accepted Answer

Primary ferritic with secondary austenite (FA mode)

Answer

FA solidification mode produces delta ferrite that rejects tramp elements (S, P) into the liquid last, preventing low-melting liquid films at grain boundaries that cause solidification cracking.

Question 3

What is the role of manganese in low-alloy steel filler metals?

Accepted Answer

Deoxidizes the weld pool and combines with sulfur to form MnS, preventing hot cracking

Answer

Manganese is a deoxidizer in weld pools and preferentially combines with sulfur to form globular MnS inclusions, preventing the formation of low-melting iron sulfide films that cause hot cracking.

Question 4

The heat-affected zone (HAZ) of a steel weld is divided into sub-zones. Which sub-zone experiences the highest peak temperature and coarsest grain structure?

Accepted Answer

Coarse-grained HAZ (CGHAZ)

Answer

The coarse-grained HAZ, immediately adjacent to the fusion line, reaches temperatures above 1100°C, causing rapid austenite grain growth that can lead to martensite with poor toughness upon cooling.

Question 5

What welding defect is characterized by a groove melted into the base metal adjacent to the weld toe that is not filled by weld metal?

Accepted Answer

Undercut

Answer

Undercut is a groove or channel melted into the base metal at the weld toe caused by excessive amperage, improper electrode angle, or travel speed, creating a stress concentration.

Architecting on AWS Certification Practice Test

Architecting on AWS Certification Practice Test

Architecting on AWS Certification Welding Metallurgy & Materials 3