1. Weld Discoloration/Oxidation
Inadequate protective gas or turbulent airflow (e.g., argon flow < 8L/min).
Uncleaned oil/grease or oxide layer on the material surface (e.g., aluminum alloy oxide film).
Excessively slow welding speed causing high-temperature oxidation.
Gas Optimization: Adjust argon flow to 15–20L/min for stainless steel welding, use a coaxial gas nozzle (3–5mm aperture) to ensure gas coverage of the molten pool.
Surface Pretreatment: Wipe copper materials with acetone before welding; mechanically grind or chemically remove rust from aluminum alloys (e.g., 5% NaOH solution).
Parameter Adjustment: Increase welding speed by 10%–20% or reduce power by 5%–10% to minimize heat input.
2. Burn-Through (Molten Pool Collapse)
Excessively high laser power (e.g., 1500W for 2mm steel plate).
Too slow welding speed or too small defocus.
Mismatch between material thickness and parameters (e.g., using thick-plate parameters for 0.5mm thin plates).
Power Control: Match power to material thickness (e.g., 400–600W recommended for 1mm aluminum plate); reduce power in stages (e.g., start at 80%, end at 60%).
Speed & Defocus: Increase welding speed from 1m/min to 1.5m/min; adjust focal position from 0mm to +0.5mm (positive defocus).
Pulse Mode: Switch to high-frequency pulses (above 200Hz) to shorten single-pulse energy action time.
3. Cold Weld (Incomplete Fusion)
Insufficient laser energy (power < 200W or excessive speed).
Focal point deviation (defocus error > ±0.3mm).
Abnormal wire feeding (e.g., wire jamming or mismatched feeding speed).
Energy Calibration: Measure laser output with a power meter (error must be < ±5%); ensure power reaches at least 300W for thin-plate welding (1mm stainless steel).
Focal Point Fine-Tuning: Calibrate the focal point using the cross-hair alignment method; use a laser tracking system (accuracy ±0.1mm) for precision welding.
Wire Feeding Optimization: Check wire feed roller pressure (0.5–0.8MPa recommended for copper wire), control wire extension to 5–8mm, and select ER4047 wire (0.8mm diameter) for aluminum alloy welding.
4. Cracking (Hot/Cold Cracks)
Material stress concentration (e.g., high-hardness steel welding).
Excessively fast cooling rate (e.g., aluminum alloy without preheating).
Too high pulse frequency causing uneven thermal cycling.
Preheating Treatment: Preheat high-strength steel to 150–200°C and aluminum alloy to 120°C using an infrared heating plate.
Process Optimization: Reduce pulse frequency to 20–50Hz; adopt an "energy ramp-up/ramp-down" mode (e.g., start at 60% → 100% → 60%).
Wire Matching: Use Ni-based wire (e.g., ERNi-1) for cast iron welding to reduce weld hardness difference; apply multi-layer multi-pass welding for thick plates to disperse stress.
5. Porosity (Internal Bubbles)
Moisture in protective gas (dew point > -40°C).
Gas adsorption on the material surface (e.g., solvent volatilization from coatings).
Molten pool metal boiling (caused by excessive power leading to vaporization).
Gas Drying: Use a molecular sieve dryer (dew point < -60°C) and ensure helium purity ≥ 99.99%.
Surface Treatment: Dry plastic materials before welding (80°C × 2h); remove coatings from metals (e.g., grind galvanized layers).
Power Adjustment: Reduce power by 10%–15% or adopt a "low-frequency pulse + slow speed" mode (e.g., pulse frequency 10Hz, speed 0.8m/min).
6. Undercut (Groove at Weld Edge)
Uneven laser energy distribution (spot ellipticity > 1.2).
Excessively fast welding speed causing insufficient molten pool filling.
Excessive protective gas blowing force dispersing molten pool metal.
Spot Calibration: Detect spot roundness with a beam analyzer and adjust the collimator to ellipticity < 1.05.
Speed & Angle: Reduce welding speed from 2m/min to 1.5m/min and control torch inclination at 15°–20°.
Gas Control: Switch to side gas blowing (45° angle) and reduce flow from 20L/min to 15L/min.
7. Incomplete Penetration (Insufficient Weld Depth)
Inadequate power (e.g., 1000W for 3mm steel plate).
Excessively large defocus (negative defocus < -1mm).
High material reflectivity (e.g., copper without blackening treatment).
Power Increase: Recommend 2000–2500W for 3mm stainless steel; switch to blue laser for copper welding (absorptivity increased to 60%).
Defocus Adjustment: Adopt negative defocus (-1.5mm) for deep penetration welding and use "oscillatory welding" (amplitude 0.5mm) to increase weld width.
Surface Treatment: Pre-plate copper with nickel (2–3μm thickness) or sandblast the surface to improve laser absorptivity.
Defect Troubleshooting Process Recommendations
Check hardware before parameters: Verify optical alignment, gas flow, and wire feeding system for abnormalities.
Single-factor testing: Adjust only one parameter (e.g., power or speed) at a time, record the effect, then optimize.
Material adaptation table: Establish a database of parameters for common materials (e.g., 0.3mm stainless steel → 300W power, 1.8m/min speed, 12L/min argon).