Stick welding (SMAW) defects look different from MIG or TIG defects, and the fixes are often different too. Porosity in a stick weld usually comes from a damp electrode, not a gas line problem. Slag inclusion does not exist in TIG at all.
This guide walks through each common SMAW defect by appearance, explains the root cause inside the stick process, and gives you the specific correction. Every amperage range in this article is a starting point. Check the electrode manufacturer specification printed on your electrode box for the exact range. For a broader look at porosity across processes, see the Porosity in Welding guide. For a visual guide to stick welding setup and amperage ranges, see the Stick Welding Amperage Chart.
Porosity in Stick Welding
Porosity appears as small holes or pinholes on the weld surface. In severe cases the holes extend into the weld metal and are visible when the bead is ground or sectioned. In stick welding the root cause is almost always gas trapped in the solidifying weld pool. Unlike MIG, where the shielding gas comes from a bottle, stick welding generates its own shielding from the electrode flux. When that shielding is compromised, porosity follows.
What it looks like: Small round or elongated cavities on the weld surface. Wormhole porosity (elongated tubular holes) indicates gas was escaping as the weld solidified. Scattered porosity (random tiny pinholes across the bead) usually points to contamination. Cluster porosity (a tight group of holes in one area) suggests a sudden contamination event.
Root causes:
- Moisture in the electrode flux. This is the most common cause of stick porosity. Electrodes stored in humid conditions or left out of the rod oven absorb moisture. When the flux burns, moisture turns to steam and gets trapped as gas pockets. Low-hydrogen electrodes such as E7018 are especially sensitive to moisture pickup.
- Draft across the weld zone. A breeze from a fan, an open door, or a ventilation system blows the shielding gas away from the weld pool. Stick welding produces heavy fumes, and many shops run exhaust fans right over the weld area. That same airflow can pull the shielding away.
- Base metal contamination. Oil, grease, paint, rust, mill scale, or moisture on the base metal vaporizes in the arc and produces gas that becomes trapped in the weld.
- Arc length too long. A long arc exposes the weld pool to the atmosphere before the flux can provide adequate coverage.
- Electrode running too hot or too cold relative to the recommended range. Out-of-range amperage affects flux performance and gas production.
How to fix:
Stop welding. If porosity appears in the first few inches, check whether the electrode has been exposed to moisture. Store electrodes in a rod oven or sealed container. Low-hydrogen electrodes (E7018, E7016, E8018) require dry storage at a temperature specified by the manufacturer. Remove the electrode if it shows signs of damp flux. Grind out the porous area to sound metal before rewelding. Eliminate drafts by repositioning the work, using welding screens, or redirecting ventilation. Clean the base metal to bright metal within the weld zone. Adjust amperage to the middle of the electrode manufacturer range and maintain a short arc length (no more than the diameter of the core wire).
Prevention:
Store electrodes in a dedicated rod oven at the temperature recommended on the box for the electrode type. Use a portable electrode caddy for the day’s work and reseal the rest. Keep the weld area free of drafts. Clean base metal with a grinder or wire brush immediately before welding. Maintain a consistent short arc length throughout the weld.
Slag Inclusion
Slag inclusion is the defect most unique to stick welding. Slag is the glassy byproduct of flux burning. In a properly made weld the slag floats to the surface and is chipped off after each pass. Slag inclusion happens when slag gets trapped inside the weld metal between passes or within a single multi-pass weld.
What it looks like: Elongated dark lines or irregular pockets within the weld metal. Slag inclusions are most visible when the weld is ground or on a radiograph. They can appear as a dark line along the fusion zone between the weld bead and the base metal.
Root causes:
- Improper interpass cleaning. On multi-pass welds, each pass leaves a slag layer. If that slag is not removed completely before the next pass, it becomes trapped in the weld stack.
- Incorrect travel angle. A travel angle that leads the arc too far forward (a steep push angle) can wash slag ahead of the weld pool and trap it at the leading edge.
- Inadequate amperage. Low amperage produces a sluggish weld pool that does not allow slag to float to the surface. The slag solidifies inside the weld instead.
- Multipass technique errors. Weaving too wide can cause slag to roll ahead of the arc and become trapped.
- Electrode manipulation issues. A whipping or dragging technique that pushes slag into the joint rather than allowing it to flow behind the puddle.
How to fix:
Grind out the inclusion completely. Do not weld over slag. Use a chipping hammer and wire brush between every pass. For deep inclusions, use a grinder to expose clean metal. Adjust travel angle to 10 to 15 degrees of drag (electrode pointing back toward the completed weld). Increase amperage to the middle or upper end of the electrode manufacturer range to keep the weld pool fluid enough for slag to float out.
Interpass cleaning checklist for slag-free welds:
| Step | Action | Why It Matters |
|---|---|---|
| 1 | Chip slag with a chipping hammer after each pass | Removes the bulk slag layer while it is still slightly bonded |
| 2 | Wire brush the bead vigorously with a stiff stainless steel brush | Removes thin slag residue and oxide film that a chipping hammer misses |
| 3 | Inspect the bead visually for any remaining slag streaks | Catches stubborn slag that needs grinding instead of brushing |
| 4 | Grind any remaining slag spots with a flap disc or grinding wheel | Deep inclusions require mechanical removal before the next pass |
| 5 | Wipe the joint with a clean rag if welding on painted or dirty base metal | Prevents recontamination of the cleaned surface |
Prevention:
Make interpass cleaning a non-negotiable step between every pass on multi-pass welds. Use a drag angle between 10 and 20 degrees depending on the joint position. Match amperage to the electrode manufacturer range for the specific rod and joint. Keep the arc length short. Do not weave so wide that the slag pool loses contact with the arc force.
Lack of Fusion and Incomplete Penetration
Lack of fusion means the weld metal did not bond to the base metal or to a previous pass. Incomplete penetration means the weld did not reach the root of the joint. These two defects are related but not the same. Both are heat-input problems that are common in stick welding when the operator is learning to balance amperage, travel speed, and electrode angle.
What it looks like: Lack of fusion appears as a visible line or gap between the weld metal and the base metal or between weld passes. The bead looks like it sits on top of the base metal instead of blending into it. Incomplete penetration leaves a gap at the root of the joint when viewed from the opposite side or on a cross-section.
Root causes:
- Low amperage. Not enough heat to melt the base metal properly. The weld pool is cold and sluggish.
- Travel speed too fast. The arc moves ahead before the base metal has time to reach melting temperature.
- Travel speed too slow with a wide weave. The weld pool gets ahead of the arc and the leading edge of the pool does not fuse to the base metal.
- Incorrect electrode angle. With too steep a push angle the arc pushes the weld pool away from the joint face.
- Electrode diameter too large for the joint. A thick electrode cannot reach the root of a narrow groove.
- Improper joint preparation. The bevel angle is too narrow or the root face is too wide for the electrode to access the root.
How to fix:
Grind out the unfused area completely. Increase amperage toward the upper end of the electrode manufacturer range. Slow travel speed enough that the arc dwells to establish a fluid puddle on both sidewalls. Maintain a 10 to 20 degree drag angle for most positions. For vertical and overhead use a slight push or neutral angle depending on the electrode type. Verify joint preparation matches the electrode diameter.
Amperage and travel speed troubleshooting:
| Observation | Likely Root Cause | Adjustment |
|---|---|---|
| Bead sits on top of base metal, no wetting at edges | Amperage too low | Increase amperage within the electrode manufacturer range. Verify the range printed on the electrode box. |
| Bead is narrow with steep shoulders, minimal sidewall fusion | Travel speed too fast | Slow down. Allow the arc to dwell briefly at each sidewall before moving forward. |
| Root remains open on the back side of the joint | Incomplete penetration; amperage too low or root face too wide | Increase amperage. Verify root opening and root face dimensions per joint design. Use a smaller electrode if needed. |
| Lack of sidewall fusion on one side of a groove weld | Electrode angle favoring the opposite side | Adjust the electrode angle to point more directly at the unfused sidewall. Use a slight oscillation. |
| Slag entrapment between passes in multi-pass weld | Poor interpass cleaning plus fusion issues | Grind out. Clean thoroughly between passes. Adjust amperage upward. See the Slag Inclusion section above. |
Prevention:
Start with the middle of the electrode amperage range and adjust based on puddle behavior. Watch the sidewalls. If the weld metal does not wet into the base metal, increase heat or slow down. Prepare joints with adequate bevel angles and root openings for the electrode diameter. Use a stringer bead technique rather than a wide weave on root and hot passes.
Cracking (Hot Cracks and Cold Cracks)
Cracks in stick welding fall into two main categories: hot cracks that form during solidification and cold cracks (hydrogen-induced cracking) that form after the weld has cooled, sometimes hours or days later. Hydrogen cracking is a serious concern with stick welding because electrode flux absorbs moisture from the air, which introduces hydrogen into the weld metal.
What it looks like: Hot cracks appear as centerline cracks running along the weld bead or as crater cracks at the end of the weld. They form during solidification as the weld pool shrinks. Cold cracks (hydrogen cracks) appear in the weld metal or heat-affected zone, often parallel to the weld toe. They may not be visible until the weld has cooled to room temperature or after 24 to 48 hours.
Root causes:
- Hot cracks: High joint restraint, poor joint fit-up, excessive travel speed, improper electrode selection for the base material, and high sulfur or phosphorus content in the base metal.
- Cold cracks (hydrogen cracks): Hydrogen introduced by moisture in the electrode flux. High-strength electrodes (E8018, E9018, E10018) and thick sections are more susceptible. Low interpass temperature, no preheat, or rapid cooling traps hydrogen in the weld and heat-affected zone.
How to fix:
Any crack must be ground out completely to sound metal. Grind a groove through the crack and use dye penetrant or magnetic particle inspection to verify the crack is fully removed. Then reweld using a qualified procedure. Do not weld over a crack. For cold cracks, the repair must also address hydrogen control. Use properly dried low-hydrogen electrodes. Apply preheat per the applicable code or manufacturer recommendation. Control interpass temperature.
Preheat and interpass temperature decision framework:
| Key Factor | What It Affects | When to Check the WPS or Applicable Code |
|---|---|---|
| Base material type and grade | Carbon equivalent, hardenability, and minimum preheat/interpass requirements | Material certification or specification |
| Material thickness and joint restraint | Cooling rate, hydrogen diffusion path, and thermal stress distribution | Joint design and weldment drawing |
| Electrode hydrogen classification | Hydrogen potential; low-hydrogen electrodes reduce but do not eliminate preheat needs | Electrode packaging and manufacturer data sheet |
| Welding procedure specification (WPS) | Defines the qualified preheat temperature range, interpass temperature limits, and post-weld heat treatment for the specific application | Required for structural, code, pressure, or safety-critical welding |
When preheat is required: The need for preheat is determined by the combined influence of base material, thickness, restraint, electrode hydrogen level, and applicable code or manufacturer requirements. There is no universal thickness or temperature threshold. Always consult the qualified WPS, applicable code, or electrode manufacturer for the specific requirements of your joint.
⚠️ Structural, code, pressure, or safety-critical welding: Any welding on load-bearing, pressurized, or code-regulated components must follow a qualified welding procedure specification (WPS). Preheat and interpass temperature values are not general recommendations. They are procedure-specific values determined by qualification testing. Do not apply general preheat guidelines to code work without qualified engineering and procedure review.
Prevention for hot cracks:
Use electrodes matched to the base material composition. Reduce travel speed. Improve joint fit-up to minimize root gap. Use backstep or skip welding techniques to manage thermal stress on long joints.
Prevention for cold cracks:
Store low-hydrogen electrodes in a rod oven at the temperature recommended by the manufacturer. Do not expose electrodes to humid air for longer than the specified holding time. Apply preheat and maintain interpass temperature per the qualified welding procedure specification (WPS). Control cooling rate after welding. For susceptible materials, apply a post-weld heat treatment (PWHT) per code requirements.
Hard warning: Structural, code (AWS D1.1, ASME Section IX), pressure, or safety-critical welding requires a qualified welding procedure specification (WPS) and a certified welder. Do not rely on general troubleshooting guidance for these applications. For more detail on crack mechanisms, see Hot and Cold Cracking in Welding.
Undercut
Undercut is a groove melted into the base metal along the toe of the weld that is not filled by the weld metal. It reduces the cross-section of the base material and creates a stress concentration point. In stick welding, undercut is usually an arc manipulation problem.
What it looks like: A ditch or groove along one or both edges of the weld bead. The base metal surface is lower at the toe of the weld than the original surface. It may look like the arc gouged a line next to the bead.
Root causes:
- Amperage too high for the electrode diameter. The arc melts the base metal faster than the weld pool can fill the edge.
- Travel speed too fast. The weld pool washes up the sidewall without depositing enough metal to fill the groove.
- Incorrect electrode angle. On a fillet weld, holding the electrode too vertical or pointing the arc directly at the vertical plate can wash metal away from the corner.
- Long arc length. A long arc concentrates heat on the base metal edges rather than the weld pool.
How to fix:
Grinding out the undercut is a repair; you must remove the undercut area and reweld. For shallow undercut, a wash pass at lower amperage can sometimes fill the groove. For deeper undercut, grind out and reweld with adjusted parameters. Reduce amperage to the lower half of the electrode manufacturer range. Slow travel speed. Adjust electrode angle to point more into the joint. On fillet welds, hold the electrode at a 45 degree angle between the two plates.
Travel angle guide for undercut prevention:
For flat position fillet welds, hold the electrode at 45 degrees between the horizontal and vertical plates with a 10 to 15 degree drag angle. For groove welds, maintain a 10 to 20 degree drag angle and point the arc slightly into the sidewall that shows undercut. The weld pool should wet evenly into both sidewalls before advancing. If undercut appears on only one side, shift the electrode angle slightly toward the affected side by 5 to 10 degrees.
Prevention:
Use amperage within the electrode manufacturer range, starting at the lower end if undercut is a recurring problem. Keep arc length short (no longer than the electrode core wire diameter). Use a consistent drag angle. Watch the toe of the weld. If the base metal edge starts to melt ahead of the weld pool, reduce amperage or increase travel speed.
Burn-through note: Burn-through happens when the arc melts completely through the base metal, leaving a hole. It is common on thin-gauge material with excessive amperage or slow travel speed. In stick welding, burn-through is more likely on sheet metal and light-gauge pipe. Reduce amperage to the lower end of the electrode manufacturer range. Increase travel speed. Use a smaller diameter electrode to reduce heat input. On thin materials, consider using E6013 or E7014 electrodes which run cooler than E6010 or E7018. Tight fit-up and a copper backup bar behind the joint help prevent burn-through on thin sections.
Overlap (Cold Lap)
Overlap, also called cold lap, happens when weld metal flows over the base metal surface without fusing to it. The weld metal rolls over the joint edges like a wave and solidifies without bonding. This is the low-heat counterpart to undercut.
What it looks like: A rolled edge of weld metal that extends beyond the weld toe but does not fuse to the base metal. You can see a shadow line or gap under the overhanging metal. It may look like the weld is sitting on top of the base metal with a visible lip.
Root causes:
- Amperage too low. The weld pool is not hot enough to melt the base metal as it flows over the surface.
- Travel speed too slow. The weld pool piles up ahead of the arc and spills over the cold base metal.
- Incorrect electrode angle. A push angle that forces the weld pool forward can cause overlap on the leading edge.
- Wrong polarity for the electrode. Some electrodes run better on DCEN (electrode negative) or DCEP (electrode positive) depending on the manufacturer recommendation. Using the wrong polarity can produce a cold puddle that does not wet properly.
How to fix:
Grind out the overlapped area to sound metal. Increase amperage within the electrode manufacturer range. Increase travel speed so the weld pool does not pile up ahead of the arc. Adjust electrode angle to a slight drag position so the arc force pushes the weld pool backward, not forward. Verify polarity matches the electrode manufacturer recommendation.
Polarity reference for common stick electrodes:
| Electrode | Typical Polarity | Note |
|---|---|---|
| E6010 | DCEP (DC electrode positive) only | DCEP is required for deep penetration. AC is not recommended. |
| E6011 | AC or DCEP | Designed for AC use but also runs on DCEP. Check the box. |
| E6013 | AC or DCEN or DCEP | Versatile. Many welders run it on DCEN for sheet metal. Test on scrap first. |
| E7014 | AC or DCEN or DCEP | Iron powder electrode. DCEN can reduce overlap risk. Check manufacturer recommendation. |
| E7018 | AC or DCEP (preferred) | DCEP produces better arc characteristics and puddle fluidity. Some versions run on AC. Check the electrode box. |
| E7024 | AC or DCEN | Iron powder electrode for high deposition. DCEN is common. |
Prevention:
Match polarity to the electrode manufacturer recommendation printed on the box. Run amperage in the middle of the range for the electrode and joint. Keep travel speed fast enough that the weld pool stays behind the arc, not under it. Use a drag angle of 10 to 20 degrees.
Excessive Spatter
Spatter is molten metal that is ejected from the weld pool and lands on the surrounding base metal. Some spatter is normal in stick welding. Excessive spatter wastes electrode material, creates extra cleanup, and can indicate a parameter or technique problem.
What it looks like: Small droplets of solidified metal scattered around the weld bead on both sides of the joint. Heavy spatter can form a crust on the base metal that requires grinding to remove.
Root causes:
- Arc length too long. This is the most common cause of excessive spatter. A long arc causes the arc to flare and eject molten metal. Stick welding should use a short, tight arc where the electrode just barely clears the weld pool.
- Amperage too high for the electrode diameter. High current forces molten metal out of the pool.
- Wrong polarity. Running a DC-positive electrode on DC negative (or vice versa) produces unstable arc conditions and increased spatter.
- Draft blowing the arc. Air movement disrupts the shielding gas envelope and makes the arc erratic.
How to fix:
Shorten the arc length. The arc should be no longer than the diameter of the electrode core wire. Reduce amperage to the middle or lower end of the electrode manufacturer range. Verify polarity is correct for the electrode (DCEP for E6010 and E7018 as typical). Eliminate drafts. Switch to a different electrode classification if spatter persists with the same settings.
Visual arc length guide:
| Arc Length | Appearance | Spatter Level | Action |
|---|---|---|---|
| Short (tight arc, electrode almost touching the puddle) | Quiet buzzing sound. Arc is compact. Weld pool is controlled. | Minimal. Normal for stick welding. | Continue. This is the correct arc length. |
| Normal (gap about equal to electrode core wire diameter) | Steady crackling sound. Arc fills the joint evenly. | Low to moderate. Some small sparks but no heavy buildup. | Acceptable range. Adjust if spatter increases. |
| Long (gap visibly larger than electrode diameter) | Loud hissing or popping sound. Arc flares wide. Weld pool is hard to control. | High. Heavy spatter buildup on both sides of the joint. | Shorten the arc immediately. Reduce amperage if needed. |
Prevention:
Keep a short arc length from the start. Set amperage in the middle of the electrode manufacturer range. Verify polarity before welding. Use a rod oven to keep electrodes dry. Check that the electrode type is compatible with the power source (AC vs. DC).
Arc Strikes and Arc Blow
Arc strikes and arc blow are different problems. An arc strike is a localized arc burn on the base metal outside the weld joint. Arc blow is a magnetic force that pushes the arc off the joint during welding. Both are common in stick welding and both can be prevented with technique adjustments.
Arc strikes:
What it looks like: A small crater or burn mark on the base metal surface where the electrode contacted the metal outside the weld joint. The mark may have a hard spot (martensite) that can be a crack initiation site on high-strength or hardenable steels.
Root causes: Striking the arc on the base metal outside the weld joint. Scratched starts that move sideways onto the base plate before entering the joint. Poor technique for starting the electrode on the joint edge.
How to fix: Grind out arc strike marks to smooth metal. For structural welding on high-strength steels, an arc strike may need to be evaluated by a welding engineer. Do not leave arc strikes on code-welded components.
Prevention: Always strike the arc within the weld joint. Use a forward scratch start that begins inside the joint groove. On restart after changing electrodes, place the electrode 1/2 inch ahead of the previous crater and draw backward into the crater before moving forward.
Arc blow:
What it looks like: The arc wanders, pushes to one side, or flares out of the joint during welding. The arc may make a sputtering or erratic sound. It is worst on DC welding near the ends of the weld joint or on corners.
Root causes: Magnetic fields generated by the welding current interact with the magnetic properties of the base metal. Arc blow is most pronounced on DC welding of thick steel with high amperage. It gets worse toward the end of a long weld or near edges and corners.
How to fix: Change the ground clamp position. Move the ground to the far end of the work piece so the magnetic field is more balanced. Wrap the work lead around the work piece to cancel magnetic fields. Switch from DC to AC power. AC reverses polarity 60 times per second (or 50 depending on line frequency), which cancels magnetic arc blow. Reduce amperage. Shorten arc length. Use backstep welding sequence.
Ground clamp position for arc blow reduction:
For a long butt weld on steel plate, place the ground clamp at the far end of the joint, not at the end where you start welding. If the arc blows as you approach the end of the weld, try placing the ground clamp at the start end. On corner joints and T-joints, split the ground between two positions to balance the magnetic field. On pipe, use a rotating ground or position the ground opposite the weld zone. For severe arc blow on DC, switch to AC welding if the electrode type permits AC operation.
Prevention:
Use AC instead of DC on thick sections where arc blow is a known problem. Position the ground clamp as far from the weld zone as possible. Use a backstep welding sequence to manage magnetic field buildup. Keep arc length short. Reduce amperage when possible.
Diagnostic Quick-Reference Table
| Defect | Appearance | Most Likely Root Cause | First Thing to Check | Primary Fix |
|---|---|---|---|---|
| Porosity | Small holes or pinholes on weld surface | Moisture in electrode or draft across weld zone | Electrode storage condition and arc length | Dry electrodes. Shorten arc. Eliminate drafts. |
| Slag Inclusion | Dark lines or pockets in weld metal | Improper interpass cleaning or incorrect travel angle | Interpass cleaning routine and electrode angle | Chip and brush every pass. Use drag angle. Check amperage. |
| Lack of Fusion | Visible gap between weld and base metal | Low amperage or travel speed too fast | Amperage setting on the electrode box | Increase amperage. Slow travel speed. Correct angle. |
| Incomplete Penetration | Root of joint not filled through | Low amperage, wrong electrode size, or tight joint fit-up | Root opening dimensions and electrode diameter | Increase amperage or use a smaller electrode. Widen root opening. |
| Hot Cracks | Centerline or crater cracks | High restraint or fast travel speed | Joint fit-up and travel speed | Reduce travel speed. Improve fit-up. Match filler to base metal. |
| Cold Cracks (Hydrogen) | Toe or HAZ cracks, delayed appearance | Hydrogen from moist electrode flux | Electrode drying and storage procedure | Use dry low-hydrogen electrodes. Apply preheat per code or WPS. |
| Undercut | Groove along weld toe | Amperage too high or travel speed too fast | Amperage relative to electrode range | Reduce amperage. Slow down. Adjust electrode angle. |
| Overlap (Cold Lap) | Rolled edge of unfused weld metal | Amperage too low or travel speed too slow | Amperage and polarity | Increase amperage. Increase travel speed. Verify polarity. |
| Excessive Spatter | Heavy droplet buildup around the weld | Arc length too long | Arc length and amperage | Shorten arc. Reduce amperage. Eliminate drafts. |
| Arc Strikes | Crater marks outside the weld joint | Poor arc-start technique | Strike location on previous weld | Always strike inside the joint groove. |
| Arc Blow | Arc wanders or pushes to one side | Magnetic field from DC current on ferrous steel | Ground clamp position | Move ground clamp. Switch to AC if electrode allows. |
When to Check the Electrode Manufacturer Manual
The electrode box is your first troubleshooting resource. Every stick electrode type has a recommended amperage range, polarity preference, and storage requirement printed on the box or listed in the manufacturer specification sheet. These values are not suggestions. They are the ranges that the electrode was designed and tested for.
Check the electrode box when:
- You are using an electrode type for the first time. Do not assume E6010 and E6011 have the same amperage range. They do not.
- You see a defect that does not respond to technique adjustments. If porosity persists with a short arc and dry electrodes, check whether the amperage is within the printed range.
- You change electrode brands. Brand A E7018 and Brand B E7018 may have different amperage ranges. The AWS classification standard defines chemistry and mechanical properties, not the optimum welding range.
- You switch between DC and AC. Not all electrodes run well on both. Always verify polarity against the manufacturer recommendation.
- You are welding in a position different from the one the electrode is rated for. Some electrodes have different amperage recommendations for flat vs. vertical vs. overhead positions.
Electrode storage is equally important. Low-hydrogen electrodes (E7018, E8018, E9018, and higher) must be stored in a rod oven at the temperature recommended by the manufacturer. Exposure to humid air for longer than the specified holding time requires re-drying. Do not assume that electrodes left on a bench overnight are still usable. For more on electrode selection, storage, and handling, see the Stick Welding Electrode Guide.
Conclusion
Most stick welding defects are fixable by adjusting one of three variables: amperage, travel speed, or electrode angle. Porosity comes from moisture or draft. Slag inclusion comes from poor interpass cleaning or wrong angle. Undercut and overlap are opposite sides of the same heat-input coin. Cracking is a separate category that demands careful attention to hydrogen control and joint restraint.
Keep a log of settings that worked for each electrode type and joint configuration. Write down the amperage, electrode type and diameter, polarity, and travel speed. The next time you see a defect, you can check your log before changing settings at random.
For visual comparison with other processes, see the MIG Defects Visual Chart. For general welding safety and PPE guidance, see the Welding Safety and PPE Guide.
Remember that the electrode box is the first thing to check when a defect appears. The manufacturer printed that information for a reason. And for structural, code, pressure, or safety-critical welding, a qualified welding procedure specification (WPS) is required. General troubleshooting guidance supports learning. It does not replace an approved procedure. Whenever preheat or postheat is involved, the values must be determined by the applicable code, the electrode manufacturer, and the qualified procedure for that specific job. There is no universal preheat chart that covers every material and electrode combination.
