Page 31 - Metallforming Magazine December 2020

FABRICATION: WELDING WELL
Tips for Troubleshooting
Arc-Weld
Defects
Porosity, excess spatter, cracking...the list of possible weld defects goes on and on, and they can be frustrating and costly. Follow these tips to help cure them, and minimize their occurrence.
BY JOHN WARD
Weld defects plague even some of the most skilled welders, and usually result from the use of incorrect parameters or welding techniques. They can be frustrating and costly, so follow the tips offered here to help cure and minimize their occurrence.
Porosity
Porosity occurs when gas pores become trapped in the
solid weld bead. They result from the absorption of gas into the molten weld pool. The gas pores can vary in size, can be distributed uniformly or in a random manner, and can be
John Ward is the editor of kingsofwelding.com, a website hosted by a group of welders dedicated to providing welding training and education.
found on the weld surface or at the center of the bead. Weld pores often are caused by the atmospheric gases nitrogen and oxygen contaminating the weld, due to insuf-
ficient gas shielding.
To troubleshoot porosity:
1. Check for sufficient shielding-gas flow. Inspect the gas
hoses and welding gun for leaks.
2. Ensure that the nozzle isn’t clogged and restricting gas flow. 3. If welding outdoors, avoid windy conditions that can
interfere with the shielding gas.
4. Verify proper gas flow using the regulator or flow meter.
Too little or too much shielding gas can cause porosity. Porosity also can originate from hydrogen and oxygen on a contaminated workpiece, such as oxidized metal or
moisture on the workpiece. In these cases:
1. Thoroughly remove any oxide film from the workpiece
surface.
2. Ensure that the workpiece and welding electrode are
completely dry before welding.
3. Use a filler metal containing deoxidants.
Excess Spatter
Weld spatter--small drops of molten metal sprayed over the workpiece during gas-metal-arc welding (GMAW)—can
result from using an incorrect setup or from dirt on the sur- face of the workpiece. It can damage the workpiece and equipment and increase cleanup time.
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