What does the term "heat input" refer to in welding?

The term "heat input" in welding specifically refers to the amount of heat energy supplied per unit length during the welding process. This concept is critical in understanding how different welding conditions, such as current, voltage, and travel speed, can affect the characteristics of the weld.

Heat input is measured in units such as joules per millimeter or kilojoules per inch and directly influences the properties of the weld, such as penetration, bead shape, and potential for distortion in the workpiece. Higher heat inputs generally lead to deeper penetration, while lower heat inputs result in less penetration and may affect the overall strength and characteristics of the joint.

Understanding this concept helps welders optimize their processes for both quality and efficiency, ensuring they produce strong, reliable welds while minimizing the risk of defects.