The Top 5 Welding Defects—and How to Avoid Them

Understanding the most common weld defects—and keeping them out of your shop—can mean the difference between a strong, safe joint and a costly, dangerous failure. Here’s a deep dive into the top 5 stick welding defects and how to avoid them... with help from proper technique, prep, and staying clean (including your FR gear).

1. Porosity

Tiny holes or voids trapped within the weld—called porosity—are dangerous because they weaken the weld internally.

• What causes it? Contaminants like rust, oil, or moisture; using a damp or low‑hydrogen electrode; moving too fast; or excessive arc length Flawless Steel Welding+10YesWelder+10Wikipedia+10.

• How to prevent it: Clean all surfaces thoroughly; keep electrodes dry and use low‑hydrogen types; control travel speed; and keep a consistent short arc length Weld Guru.

2. Incomplete Fusion

When the weld metal doesn’t properly fuse to the base material, the bond is weak and incomplete.

• Why it happens: Low current, incorrect electrode angle, poor surface prep, or improper technique Flawless Steel Welding+11Wikipedia+11aast.edu+11Wikipedia+1.

• Fix it by: Using correct amperage; adjusting electrode angle and arc length; cleaning surfaces; and employing proper stick manipulation and pass technique Weld GuruWikipedia.

3. Undercut

This appears as a groove or notch running along the edge of the weld, weakening the joint.

• Common causes: Excessive current, fast travel speed, long arc, poor technique, or wrong electrode angle Amazon+15Wikipedia+15Weld Guru+15.

• How to prevent: Dial back amperage; maintain a short arc; slow your travel speed; use the correct angle; and use multiple passes when welding thicker materials YesWelder.

4. Slag Inclusions

Slag gets trapped inside the weld and prevents proper cohesion, leading to weak spots.

• Why it happens: Occurs when slag from a previous pass isn’t removed, or there’s poor overlap TFT Pneumatic+5Wikipedia+5Wikipedia+5.

• Prevent it by: Cleaning and chipping slag between passes; brush after each pass; use proper technique and maintain good weld bead overlap WikipediaTFT Pneumaticsmith-iron.com.

5. Cracks (especially cold cracks)

Cracks can form at or after welding—often not visible right away—and are among the most dangerous defects.

• Types & causes:

  • Cold cracks due to hydrogen embrittlement, rapid cooling, or residual stress YesWelder+15Wikipedia+15TFT Pneumatic+15.

  • Hot cracks during solidification from impurities or poor joint design Flawless Steel Welding+1.

• Prevention: Preheat the base metal; bake electrodes and use low‑hydrogen consumables; slow down the cooling; minimize restraint; use proper joint design and filler material Wikipedia+1Flawless Steel Welding.

Proven Tips to Keep Weld Quality Tight

• Rigorous Prep: Clean metal surfaces and maintain dry, quality electrodes.

• Get Your Settings Right: Choose correct current, short arc length, proper travel speed, and electrode angle.

• Layer Smart: Clean between passes to avoid slag inclusions and ensure strong fusion each time.

• Watch Cooling: Preheat when needed, and avoid rapid cooling and restraint that can cause cracking.

• Inspect as You Go: Use visual checks and, when possible, weld‑cam systems or NDT to catch defects early Flawless Steel Welding+1Weld Guru+1Wikipedia+2UTI Corporate+2Wikipedia+2blog.xiris.com+2.