List 4 welding discontinuities.

List 4 welding discontinuities.

• A. Surface roughness, burn-through, porosity
• B. Porosity, undercut, Lack of fusion, Slag
• C. Cracks in HAZ, porosity, slag
• D. Undercut, porosity, misalignment

Answer: (B)

Welding discontinuities are flaws in a weld that can weaken the joint and affect performance. Four commonly recognized discontinuities inspectors look for are porosity, undercut, lack of fusion, and slag. Porosity means gas pockets trapped in the weld metal, usually from improper shielding, contamination, or too rapid cooling. These pores create weaknesses in the weld metal and can reduce strength and toughness. Undercut is a groove melted into the base metal at the toe of the weld, which leaves a notch along the weld contour. That reduces the effective throat thickness and concentrates stress, making cracks more likely under load. Lack of fusion occurs when the weld metal does not properly fuse with the base metal or with a previous weld pass, creating a rough, unbonded interface that weakens the joint. Slag refers to nonmetallic inclusions that become trapped in the weld metal or along the weld surface, which can act as stress risers and corrosion sites. These four are a standard set you’d expect to identify in bridge welding inspections. Other options mix items that aren’t all four typical discontinuities, such as surface features or defects not categorized as common weld discontinuities, so they don’t represent the same four-category list.

Welding discontinuities are flaws in a weld that can weaken the joint and affect performance. Four commonly recognized discontinuities inspectors look for are porosity, undercut, lack of fusion, and slag.

Porosity means gas pockets trapped in the weld metal, usually from improper shielding, contamination, or too rapid cooling. These pores create weaknesses in the weld metal and can reduce strength and toughness. Undercut is a groove melted into the base metal at the toe of the weld, which leaves a notch along the weld contour. That reduces the effective throat thickness and concentrates stress, making cracks more likely under load. Lack of fusion occurs when the weld metal does not properly fuse with the base metal or with a previous weld pass, creating a rough, unbonded interface that weakens the joint. Slag refers to nonmetallic inclusions that become trapped in the weld metal or along the weld surface, which can act as stress risers and corrosion sites.

These four are a standard set you’d expect to identify in bridge welding inspections. Other options mix items that aren’t all four typical discontinuities, such as surface features or defects not categorized as common weld discontinuities, so they don’t represent the same four-category list.