CRI Welding Defects Identification

Question 1

What is porosity in welding?

Accepted Answer

Gas pockets or voids within the weld metal.

Answer

Porosity in welding refers to the presence of gas pockets or voids trapped within the solidified weld metal. These can be spherical or elongated and are typically caused by gases (like hydrogen, oxygen, or nitrogen) failing to escape the molten weld pool before it solidifies. Porosity weakens the weld and can lead to structural failure.

Question 2

Which welding defect is caused by excessive heat and poor technique?

Accepted Answer

Cracking.

Answer

Cracking in welds is often caused by a combination of excessive heat input, rapid cooling rates, and high residual stresses, especially in susceptible materials. These factors can lead to the formation of brittle areas or stress concentrations that result in cracks during or after solidification. Poor technique and improper material selection also contribute to cracking.

Question 3

What is undercut in welding?

Accepted Answer

A groove at the weld toe reducing cross-section.

Answer

Undercut in welding is a groove melted into the base metal adjacent to the weld toe or root, which reduces the effective thickness of the base metal. This reduction in cross-section weakens the joint and can act as a stress concentrator, potentially leading to fatigue failure. It is often caused by excessive arc voltage or travel speed.

Question 4

Which defect occurs when the weld metal does not properly fuse with the base metal?

Accepted Answer

Lack of fusion.

Answer

Lack of fusion occurs when the molten weld metal fails to properly coalesce and bond with the base metal or with previous weld passes. This creates unbonded areas within the weld joint, significantly reducing the weld's strength and integrity. It is a critical defect that can lead to structural failure.

Question 5

What is overlap in welding?

Accepted Answer

Excess weld metal over base metal without fusion.

Answer

Overlap is a welding defect where the weld metal flows over the surface of the base metal without actually fusing to it. This creates a weak mechanical bond rather than a strong metallurgical one, forming a lip or protrusion. It indicates insufficient heat input or improper welding technique, which can act as a stress concentrator.

(CRI) Certified Radiographic Interpreter Practice Test

(CRI) Certified Radiographic Interpreter Practice Test

CRI Welding Defects Identification