Activity 002: Weld Defect Identification Lab¶
Activity ID: U6M1-ACT-002 Duration: 30 minutes Objective: Students will examine sample welds containing intentional defects, identify each defect type, determine the cause, and recommend corrective actions. Group Size: 2-3 students
Overview¶
Using a set of pre-made weld samples that exhibit common defects, students will practice visual inspection techniques and build their defect recognition vocabulary. This observational skill is essential before students begin welding — knowing what bad looks like helps them produce good welds.
Materials & Equipment Needed¶
- 8 weld sample coupons (prepared by instructor) showing:
- Sample 1: Porosity (scattered gas pores)
- Sample 2: Undercut (groove melted into base metal at weld toe)
- Sample 3: Lack of fusion / cold lap
- Sample 4: Excessive spatter
- Sample 5: Burn-through (hole melted through thin material)
- Sample 6: Excessive reinforcement (too tall/convex)
- Sample 7: Inconsistent bead width (poor travel speed control)
- Sample 8: Good quality reference weld
- Magnifying loupe (10×)
- Fillet weld gauge
- Weld inspection worksheet
- Weld defect reference poster or handout
Instructions & Procedure¶
Phase 1: Reference Study (5 minutes) 1. Examine Sample 8 (the good weld reference) carefully 2. Note: consistent width, smooth ripple pattern, proper fusion at toes, appropriate reinforcement, no visible defects 3. This is your baseline — compare all other samples against it
Phase 2: Defect Identification (15 minutes) For each sample (1-7), record on the worksheet: 1. What you see: Describe the visual appearance of the defect 2. Defect name: Identify the defect type using the reference handout 3. Probable cause: What welding error created this defect? 4. Corrective action: What parameter or technique change would prevent this defect? 5. Severity: Would this weld pass a visual inspection? (Accept / Reject)
Use the fillet gauge to measure leg size and reinforcement where applicable.
Phase 3: Group Discussion & Ranking (10 minutes) 1. As a group, rank the 7 defects from most to least structurally dangerous 2. Discuss: which defects are visible on the surface vs. which require destructive testing to find? 3. Identify which defects are caused by parameter errors (machine settings) vs. technique errors (operator skill) 4. Present your top 3 most dangerous defects to the class with justification
Discussion Points¶
- Why is lack of fusion one of the most dangerous defects? (It can look good on the surface while being completely unfused underneath)
- How does travel speed affect three different defect types?
- Which defects could be caused by contamination vs. incorrect parameters?
- In a makerspace setting, how thorough should weld inspection be compared to a structural steel shop?
Expected Outcomes¶
- Students can visually identify 7 common weld defects
- Students understand the relationship between welding variables and defect formation
- Students can recommend specific corrective actions for each defect type
Assessment Rubric¶
| Criteria | Excellent (4) | Proficient (3) | Developing (2) | Beginning (1) |
|---|---|---|---|---|
| Defect Identification | All 7 correctly identified and named | 5-6 correctly identified | 3-4 correctly identified | Fewer than 3 identified |
| Cause Analysis | Accurately links all defects to causes | Most causes correct | Some causes identified | Cannot determine causes |
| Corrective Actions | Specific, actionable corrections for each | Reasonable corrections for most | Vague or partial corrections | No viable corrections |
| Structural Assessment | Correctly ranks danger with engineering justification | Reasonable ranking | Partially correct ranking | No structural understanding |
Safety Considerations¶
- Weld samples may have sharp edges — handle with leather gloves
- Some samples may have loose spatter that can flake off — wear safety glasses
- Do not attempt to break or bend samples without instructor permission
- This is an observation/analysis activity — no welding or grinding
Last Updated: 2026-03-19