How do you troubleshoot common SMAW problems like arc blow or porosity?

1 What is arc blow?

Arc blow is a phenomenon that occurs when the magnetic field around the arc is distorted by the presence of ferromagnetic materials, such as the workpiece, the electrode, or the welding machine. This can cause the arc to deflect, wander, or split, resulting in irregular and uneven welds, spatter, undercut, or lack of fusion. Arc blow is more likely to happen when welding near the edges, corners, or joints of the workpiece, or when using direct current (DC) with high amperage.

2 How to prevent and correct arc blow?

To prevent arc blow, it is best to avoid welding near magnetic sources or use AC instead of DC. If welding with DC near magnetic sources is unavoidable, there are several methods that can reduce or eliminate arc blow. These include changing the polarity of the electrode or workpiece, altering the position or angle of the electrode, using a shorter arc length and smaller electrode diameter, and employing a drag or backhand technique instead of a push or forehand technique. These strategies can help you find a more stable arc path and maintain better control over the arc to avoid spatter.

3 What is porosity?

Porosity is a defect that occurs when gas bubbles are trapped inside the weld metal, creating small holes or cavities. Porosity can weaken the weld and reduce its corrosion resistance, ductility, and fatigue strength. Porosity is caused by various factors, such as moisture, dirt, oil, rust, or paint on the workpiece or the electrode, insufficient shielding gas, improper welding technique, or excessive welding speed.

4 How to prevent and correct porosity?

The best way to prevent porosity is to make sure the workpiece and electrode are clean and dry before welding, and that the shielding gas is adequate and consistent. If you encounter porosity during or after welding, you can try increasing the welding current and voltage, decreasing the welding speed and increasing the dwell time, using a weaving or oscillating technique instead of a straight technique, or grinding out the porous areas and re-welding them. The latter may require additional inspection and testing to ensure quality. All of these methods can help melt the gas bubbles and fill the holes with more metal, avoid skipping over the gas pockets, distribute heat more evenly, and break up the gas bubbles.

5 How to identify SMAW problems?

An industrial maintenance welder must be able to identify SMAW problems and their causes by inspecting welds visually or using non-destructive testing methods. Common signs of SMAW issues include arc blow, which can be evidenced by an irregular bead shape, spatter, undercut, lack of fusion, or cracks along the weld edges or corners. Porosity is another common issue that can be seen as small holes or cavities on the weld surface or inside the weld metal, visible as dark spots on radiographic or ultrasonic tests. Other SMAW problems may include slag inclusions, incomplete penetration, distortion, cracking, or burn-through.

6 How to improve your SMAW skills?

The best way to improve your SMAW skills and avoid common problems is to practice regularly and follow the recommended procedures and parameters for your welding project. You should also check and maintain your welding equipment and consumables, and use the appropriate personal protective equipment (PPE) and safety measures. Additionally, you should seek feedback and guidance from experienced welders or instructors, and keep learning from your mistakes and successes.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?