Which type of welding discontinuity is considered the least offensive?

Porosity is generally considered the least offensive type of welding discontinuity because it is often small and may not significantly impact the overall integrity of a welded joint, especially in non-critical applications. While porosity can indicate problems with the welding process, such as contamination or improper shielding gas coverage, the physical implications typically lead to less compromise in the weld's strength compared to other discontinuities like cracks, inclusions, or undercut.

Cracks, for example, can lead to complete failure and are dangerous even in small sizes, compromising the structure's integrity. Inclusions refer to non-metallic material becoming trapped in the weld, which can adversely affect mechanical properties and fatigue life. Undercut is a groove that occurs at the base of the weld, reducing the effective area and can lead to stress concentrations.

In conclusion, while none of these discontinuities are ideal, porosity tends to have a lesser impact on performance and can often be remedied or tolerated in certain applications, placing it in the category of least offensive welding defects.