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Eight Common Welding Defects: A Practical Diagnostic Starting Point
A defect name is the beginning of an investigation, not a diagnosis. The same visible symptom can have several causes, and acceptance depends on the governing requirements. Use this overview to choose an initial investigation path, then apply the detailed procedure.
01Cracking and porosity
For cracking, identify the location, orientation, timing, material, and process before proposing a correction. Hydrogen cracking, solidification cracking, and other mechanisms need different responses. For porosity, examine cleanliness, consumable condition, shielding or flux protection, and process conditions. Do not assume that grinding the visible surface reveals the full extent of either problem.
02Incomplete fusion and slag inclusion
Investigate access, joint preparation, electrode or torch location, bead profile, operating range, and cleaning. A visually wide bead does not establish sidewall fusion. Slag can remain in inaccessible regions or between passes. Current adjustment alone may not address the geometry or technique that created the problem.
03Undercut and burn-through
Undercut concerns the weld-to-parent transition; burn-through concerns loss of control at the root or a thin section. Review the joint geometry, fit-up, heat balance, travel, and filler delivery for the actual process. Do not treat an increase or decrease in one parameter as a universal remedy. Check dimensions against the specified acceptance criteria.
04Excessive spatter and oxidation
Spatter can be associated with transfer mode, settings, delivery instability, contamination, or electrical problems. Oxidation requires investigation of material, shielding, backing protection, contamination, and thermal exposure. Color alone is not a complete acceptance test. Determine whether the issue affects surface preparation, downstream coating, corrosion service, or another specified requirement.
05Use a repeatable investigation sequence
Identify and isolate the affected work. Record the symptom and its location, then confirm the applicable WPS, material identity, consumable, and recent changes. Inspect preparation and equipment before changing multiple settings. Test the supported corrective action on representative work and perform the required reinspection before restarting unrestricted production.
06Keep repair and prevention connected
Define the extent of unacceptable material and obtain the required repair disposition. Preserve observations from the excavation where they help diagnosis. Track recurrence by joint, station, shift, and operating conditions. A passing repair does not by itself prove that the production cause has been removed.
07Looking Ahead
Use the defect overview as a routing tool. Detailed guides, procedure limits, and competent examination should determine the corrective action and acceptance decision for each actual weld.
Keep the Decision Evidence-Based
Use the defect name to start the investigation, then verify the supported cause and repair route.