Which factor can adversely affect the quality of a weld?

Poor cleanliness of the base material is a significant factor that can adversely affect the quality of a weld. When the surface of the base material is contaminated with dirt, oil, rust, or other impurities, it can lead to issues such as lack of fusion, porosity, and slag inclusion in the weld. These flaws can compromise the strength and integrity of the weld joint, ultimately affecting the performance of the welded structure.

In contrast, selecting appropriate filler material, maintaining consistent travel speed, and working in a controlled environment all contribute positively to the welding process. Proper filler material ensures compatibility with the base metals, consistent travel speed aids in achieving uniform bead appearance and quality, and a controlled environment minimizes variables like temperature and wind that could introduce defects. Therefore, maintaining cleanliness is crucial for achieving a high-quality weld.