Which welding parameter can directly influence arc blow?

Heat input is a critical factor that can directly influence arc blow during the Shielded Metal Arc Welding (SMAW) process. Arc blow occurs when the arc is deflected from its intended path due to magnetic fields, often caused by the interaction of electrical current with the magnetic properties of the workpiece material. Higher heat input can lead to increased temperatures in the weld area, which can alter the magnetic field patterns and exacerbate arc blow.

When heat input is increased, it can also lead to changes in the physical state of the base metal, affecting its magnetic properties. As the workpiece heats up, the structure may become less stable, potentially increasing the likelihood of arc blow. Therefore, understanding and managing heat input is essential for maintaining arc stability and ensuring consistent weld quality.

Other parameters, while they may have some influence on the welding process, do not have the same direct correlation with arc blow as heat input does. For example, the electrode diameter influences the amount of metal deposited but does not inherently change the magnetic effects in the weld area. Similarly, travel angle and electrode polarity have roles in determining welding efficiency and bead appearance but do not directly impact the magnetic factors that lead to arc blow.