| Imperfection type | Why critical for aluminium | |------------------|----------------------------| | (hot, crater, longitudinal) | High solidification shrinkage + low ductility at high temp | | Porosity (gas pores, wormholes) | Hydrogen absorption from moist oxide or shielding gas | | Lack of fusion / incomplete penetration | Oxide layer (Al₂O₃) melts at ~2072°C, base Al at ~660°C | | Undercut | Lower surface tension in molten aluminium | | Excess reinforcement / concavity | Strength loss or stress concentration | | Inclusions (tungsten from GTAW, oxide) | Tungsten arc instability or improper cleaning |
– Aluminium allows slightly larger pores in Level D, but Level B is almost as strict because of fatigue concerns. iso 10042 pdf
If you are writing a full technical article, you could expand this piece with: | Imperfection type | Why critical for aluminium