Arc deflection refers to the deviation or bending of the welding arc from its intended path during the welding process. A specific and common phenomenon involving arc deflection in welding is known as arc blow.
Understanding Arc Blow
Based on common welding terminology and the provided reference, arc blow is described as:
Such arc deflection, usually forward or backward of the welding direction, is known as 'arc blow'.
This indicates that arc blow is a form of arc deflection that specifically causes the arc to move, typically in the direction of welding (forward) or away from it (backward).
Causes of Arc Blow
The reference highlights the primary conditions under which arc blow tends to occur:
- Residual Magnetism: The material being welded has residual magnetism present at a certain level.
- Weld Location: It is particularly common when the weld root is being made.
- Welding Current: The welding current being used is direct current (DC), whether positive (DCEP) or negative (DCEN).
These factors combine to create magnetic forces that can disrupt the stable path of the welding arc, causing it to deflect.
Effects and Implications
When the welding arc is deflected by arc blow, it can lead to several welding issues:
- Poor Penetration: The arc may not properly fuse the joint, especially at the root.
- Uneven Bead Profile: The weld bead can become irregular.
- Increased Spatter: Excessive spatter can occur due to the unstable arc.
- Porosity: Gas bubbles may become trapped in the weld metal.
- Undercut: Grooves may form along the edge of the weld.
These issues can compromise the quality and integrity of the weld joint.
Managing Arc Blow
While the reference focuses on the definition and causes, common industry practices to mitigate arc blow often involve:
- Using alternating current (AC) welding instead of DC where possible, as AC constantly reverses polarity, minimizing persistent magnetic forces.
- Demagnetizing the workpiece before welding.
- Adjusting the welding technique, such as changing the arc length or travel speed.
- Using run-out tabs to help stabilize the arc at the beginning and end of the weld.
- Changing the ground clamp location.
Understanding arc deflection, particularly in the context of arc blow, is crucial for welders to achieve consistent, high-quality welds, especially when working with magnetic materials or performing root passes with DC welding.
