A shipyard welder is preparing a large structural steel assembly. After welding a full penetration butt joint using the Shielded Metal Arc Welding (SMAW) process, the fit-up technician notices that the completed weld has drawn the plates out of alignment, creating an angular distortion. What is a primary contributing factor to this type of distortion in a butt joint weld?

Question: A shipyard welder is preparing a large structural steel assembly. After welding a full penetration butt joint using the Shielded Metal Arc Welding (SMAW) process, the fit-up technician notices that the completed weld has drawn the plates out of alignment, creating an angular distortion. What is a primary contributing factor to this type of distortion in a butt joint weld?

Answer options: ✅ Uneven heat input and cooling across the joint thickness

• Incorrect electrode classification for the base metal
• Excessive root opening
• Too low welding current

Correct answer: Uneven heat input and cooling across the joint thickness

Explanation: Uneven heat input and cooling across the joint thickness is a primary cause of angular distortion in butt welds. The shrinkage of the weld metal and the heat-affected zone on one side of the neutral axis causes the plates to pull out of alignment. Incorrect electrode classification might affect mechanical properties but not directly cause angular distortion. Excessive root opening or too low welding current would likely lead to other defects like lack of penetration or insufficient fill, rather than primarily angular distortion.