Weld Defect Examples for Beginners

Use these common weld defect examples to compare practice welds, spot likely problems, and decide what to adjust before your next bead.

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DimeVision gives practice feedback only. It does not certify welds or determine code compliance. A qualified inspection makes the acceptance call.

Common Defect Examples

Porosity

Small holes or pinholes in the bead

Porosity usually looks like tiny pits, bubbles, or craters. It often points to contamination, moisture, poor gas coverage, or wind around the weld.

Clean the joint back to bright metal.
Check shielding gas flow and wind protection.
Keep filler and electrodes dry.

Undercut

A groove along the weld toe

Undercut appears as a narrow channel melted into the base metal at the edge of the weld. It can create a weak stress point.

Lower heat input if the edge is washing away.
Correct torch or rod angle.
Use steadier travel and avoid excessive weaving.

Lack of Fusion

Weld metal sitting on top instead of tying in

Lack of fusion can look like a cold bead with edges that do not blend into the base metal or previous pass.

Increase heat enough for the joint.
Slow travel speed and pause at the toes.
Remove mill scale, rust, and slag between passes.

Cracks

Visible lines in the bead or heat-affected zone

Cracks are one of the most serious visible defects. They may show up at the crater, through the bead, or next to the weld.

Do not treat cracked practice welds as acceptable.
Fill craters before stopping.
Have a qualified person review the cause and the repair method before you rely on the joint.

Excessive Spatter

Metal BBs scattered around the weld

Some spatter is normal in practice, but heavy spatter can point to voltage, wire feed, stickout, polarity, or dirty metal issues.

Balance wire speed and voltage.
Check contact tip and ground clamp.
Clean the workpiece before welding.

Overlap

Weld metal rolls over without blending

Overlap looks like the bead has spilled onto the base metal without fusing at the edge. It often comes from low heat or poor angle control.

Add enough heat to wet the edges.
Use a tighter arc or correct work angle.
Avoid depositing too much metal too slowly.

Incomplete Penetration

The root is not fused through the joint

On groove welds, incomplete penetration means the weld does not reach the needed depth at the root.

Check root opening and joint prep.
Use enough amperage for the root pass.
Slow down enough to tie in the root.

Uneven Bead

Width, height, or ripple spacing changes

An uneven bead often means travel speed, work angle, arc length, or hand position changed during the pass.

Brace your hand before starting.
Keep a consistent travel speed.
Practice short beads before full joints.

Beginner Practice Checklist

What You See	Likely Practice Focus	Next Step
Holes or pits	Cleanliness and gas coverage	Clean metal, block wind, confirm shielding gas.
Groove at bead edge	Heat, angle, and travel control	Reduce edge washout and keep the puddle controlled.
Cold bead sitting high	Fusion and tie-in	Increase heat or slow travel enough to wet both edges.
Random bead width	Body position and speed consistency	Run shorter practice beads and keep your hand braced.

Use a Photo to See What to Fix Next

DimeVision flags visible issues like porosity, undercut, spatter, and bead consistency, then says what to fix on the next pass. It is a practice aid, not a final inspection.

For a deeper reference, see the weld defect identification guide and the weld quality check.

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