AWS Welding Inspection and Testing Certification Practice Test

What is the discontinuity called that results from gas entrapment within the weld?

1. Crack

2. Slag inclusion

3. Undercut

4. Porosity

The correct answer is: Porosity

The discontinuity known as porosity results from gas entrapment within the weld. During the welding process, gases can become trapped in the molten weld metal as it solidifies. This entrapment typically occurs due to insufficient shielding of the molten pool or the presence of contaminants in the base materials or filler metals. As the weld cools and solidifies, these trapped gases create small voids or pockets within the weld, leading to porosity. Porosity can negatively affect the mechanical properties of the weld, such as its strength and ductility, as well as its corrosion resistance. Identifying and controlling porosity is crucial for ensuring the integrity of welded structures. The other discontinuities mentioned, such as cracks, slag inclusion, and undercut, are different types of weld defects that arise from other factors and mechanisms rather than gas entrapment. Each of these has distinct characteristics and implications for weld quality but does not relate to gas entrapment in the same way that porosity does.