Atlas of Casting Defects
Negative
Jagged crack with irregular path
N/A
Geometry involves seriously restrained contraction or in a local volume of unfed metal. May occur at the intersection of thick and thin section.
N/A
Visual inspection and Penetrant inspection typically reveal cracks. Cracks form roughly 90° to stress direction.
Typically, internal stresses from solid-state cooling or rapid cooling can caused cracking.
| Area | Possible Cause | Potential Correction |
|---|---|---|
| Wax | Major sectional changes in the casting design |
Modify gating to prevent strong gates or runners from preventing the casting from contracting |
| Wax | Restriction of casting contraction at elevated temperature |
Modify the design to avoid contraction restriction and strengthen the weak areas by the use of webs |
| Foundry | Premature movement of mold after casting |
Allow time for the casting to solidify before moving |
| Other (Post-cast operation) | Uneven cooling rate -The use of water to cool a hot casting can sets up high internal stress |
Avoid rapid cooling methods |
| Other (Post-cast machining) | Removal of cast material can create an imbalance of the internal stress leading to cracking. |
Add a stress-relief thermal cycle to as-cast part prior to metal removal operations |
| Other (Casting design) | Restriction of casting contraction at elevated temperature |
Modify the design to avoid contraction restriction and strengthen the weak areas by the use of webs |
| Other (Casting design) | Major sectional changes in the casting design |
Modify gating to prevent strong gates or runners from preventing the casting from contracting |
| Other (Casting design) | Sharp internal angles |
Ensure adequate fillet radii |