AWS Welding Inspection and Testing Certification Practice Test

Excessive heat input during the welding process primarily compromises the mechanical properties of the weld. This occurs because high heat can lead to several adverse effects on the microstructure of the welded material. When the heat input is too high, it can cause grain growth, which reduces the strength and toughness of the weld. Additionally, overheating can lead to the formation of undesirable phases, such as martensite in carbon steels, which may negatively impact ductility and overall durability.

These negative changes can result in increased susceptibility to issues like cracking, reduced fatigue life, and lower overall performance of the welded joint under loads. While it may seem that more heat could enhance certain aspects of welding, the balance of heat input must align with the material properties and the intended use of the weld to maintain the integrity of the joint.