Review common causes of slag inclusions with SJ601, including joint geometry, bead placement, incomplete cleaning, parameters, and contaminated flux.
Slag inclusions occur when nonmetallic slag becomes trapped inside the weld. SJ601 does not create inclusions automatically; defects normally result from the interaction of joint design, bead placement, parameters, and cleaning.
What Are the Main Causes?
- Incomplete slag removal between passes
- Narrow groove angle
- Improper electrode position
- Concave or undercut bead profile
- Excessive travel speed
- Insufficient heat input
- Incorrect wire placement
- Irregular flux coverage
- Contaminated or heavily degraded recycled flux
- Poor bead sequencing
Why Are Multi-Pass Welds Vulnerable?
Slag can remain at the bead toe or between overlapping passes. If the next pass does not remelt or displace it, the material becomes trapped.
How Can Operators Prevent Inclusions?
- Use a qualified joint design.
- Maintain correct wire alignment.
- Keep parameters within the WPS.
- Produce accessible bead profiles.
- Remove slag fully after every pass.
- Grind difficult areas when necessary.
- Screen recycled flux.
- Inspect the groove before continuing.
Is Easy Slag Removal Enough?
No. Even a flux with good slag detachability can produce inclusions if bead geometry or pass placement is poor.
Dayang Welding recommends evaluating SJ601 as part of the complete welding procedure and training operators to identify high-risk locations before depositing the next pass.
